CN104253956B - Low-power-consumption voltage-stabilizing backlight control circuit and television - Google Patents

The invention discloses a low-power-consumption voltage-stabilizing backlight control circuit, which comprises: the device comprises a front-end power supply circuit, a DC-DC voltage regulating circuit, a rear-end linear constant current circuit and a voltage detection circuit; the front-end power supply circuit comprises a power supply circuit, a first power supply output end, a second power supply output end and a feedback circuit; the feedback circuit controls the power supply circuit to adjust the voltage values of the first power supply output end and the second power supply output end according to the voltage value of the control signal input end; the DC-DC voltage regulating circuit regulates the voltage signal output by the second power supply output end into a fixed voltage signal; the invention also provides a television with self-adaptive power supply regulation. The technical scheme provided by the invention can control the output voltage of the circuit, stabilize the power supply voltage of the mainboard and prevent the micro-lighting phenomenon of the LED when the backlight is turned off.

A kind of voltage stabilizing backlight control circuit of low-power consumption and television set

Technical field

The present invention relates to power supply technical field, more particularly to a kind of low-power consumption voltage stabilizing backlight control circuit and including The television set that the adaptation power supply of the voltage stabilizing backlight control circuit of the low-power consumption is adjusted.

Background technology

In TV set power control technology field, often realized using one-level Heising modulation circuit simultaneously to mainboard and The power supply of LED-backlit.

Heising modulation circuit is widely used a kind of element circuit in Analogous Integrated Electronic Circuits, can be used as power circuit.Its Multiple-channel output transformator is provided with generally, by the multiple-channel output transformator, extraction exports supply electricity output as LED-backlit all the way End, then another road output is drawn as the power supply outfan of mainboard.Carrying out to television components in integration process, mainboard and the back of the body Light lamp bar generally needs to form a complete production network, and the different backlight LED light bars of quantity will need the output of power circuit adaptability different Magnitude of voltage.The feedback circuit being connected using a kind of outfan of powering with TV SKD in prior art, timely monitoring television The change in voltage of main board power supply outfan.

As shown in figure 1, being a kind of schematic diagram of Heising modulation circuit that prior art is provided.When main board power supply outfan When output voltage is raised, the voltage signal after resistance RB135 and resistance RB134 partial pressures is linked into the ginseng of stabilivolt UB102 In examining input R, and the voltage signal is made comparisons with the reference voltage (such as 2.5V) inside stabilivolt UB102 so that Voltage is reduced between stabilivolt UB102 anode and cathodes, and then the electric current of optocoupler diode PCB101A becomes big, colelctor electrode and emitter stage Between dynamic electric resistor diminish, the voltage step-down between colelctor electrode and emitter stage, the inside transformation in linear constant current circuit therewith Device output voltage is reduced to the voltage of setting.Therefore, with the increase of resistance RB134 resistances, power outfan and mainboards of LED is supplied The output voltage at electricity output end reduces, otherwise voltage is raised.

Due to the difference of application scenario, in the reality of LED (Light Emitting Diode, light emitting diode) television set Linear constant current circuit is generally required in production process and exports different magnitudes of voltage, and the power supply exported to TV SKD and backlight End is typically each under the jurisdiction of same transformator, when outfan of powering all the way to any of which is modulated, will necessarily be to another The power supply outfan on road produces impact.For example, generally require that output is adjusted according to the number change of backlight LED extremely in practice The supply voltage of LED string, and the supply voltage of TV SKD is relatively fixed, therefore, prior art cannot be met in adjustment LED power outfan output voltage values while, adaptively keep supply TV SKD voltage stabilization demand.

Additionally, prior art to linear constant current circuit when being improved, the power supply in shut-off backlight LED is often caused When, one end of backlight LED is still connected with electricity consumption device and there is weak current so that the weak current is played a reversed role to backlight LED So that backlight LED turns on and send faint light, this is not allowed in television set manufacturing technology field.

The content of the invention

The technical problem to be solved is to provide a kind of voltage stabilizing backlight control circuit of low-power consumption, can be complete Shut-off backlight of television LED, it is to avoid unnecessary power consumption penalty and the service life for improving backlight LED.

To solve above technical problem, on the one hand, the present invention provides a kind of voltage stabilizing backlight control circuit of low-power consumption, it is special Levy and be, including：Front end power circuit, DC-DC voltage regulator circuits, rear end linear constant current circuit and voltage detecting circuit；

The front end power circuit includes power supply circuits, the first power supply outfan, the second power supply outfan and feedback circuit；

The feedback circuit includes that feedback signal input terminal, control signal input, adjustable mu balanced circuit and optocoupler drive Circuit；The feedback signal input terminal is connected with the described second power supply outfan；The control signal input is by external control Signal accesses to the reference input of the adjustable mu balanced circuit；The power supply circuits are carried out by the external control signal Control, so as to adjust the output voltage values of the first power supply outfan and the second power supply outfan；

Wherein, the first power supply outfan is connected with the anode of LED string, for powering to LED backlight；It is described The input of DC-DC voltage regulator circuits be connected with the described second power supply outfan, for described second to be powered outfan institute The voltage signal of output is adjusted to after fixed voltage signal, is exported to TV SKD and is powered；

The rear end linear constant current circuit, the electric current for controlled output to the LED string is constant current signal；

The input of the voltage detecting circuit is connected to the junction of the constant-current control circuit and the LED string, The outfan of the voltage detecting circuit is voltage detecting outfan, for when the LED string is turned on, by the voltage Detection output exports the magnitude of voltage of the constant-current control circuit and the junction of the LED string；Close in the LED string When, shut-off flows through the electric current of the LED string.

Further, the rear end linear constant current circuit includes constant-current control circuit and a switching tube (QB1)；

When the switching tube (QB1) is audion, the constant-current control circuit by the colelctor electrode of the audion with The negative electrode connection of the LED string；

When the switching tube (QB1) is field-effect transistor, the constant-current control circuit passes through the field effect transistor The drain electrode of pipe is connected with the negative electrode of the LED string.

Further, it is additionally provided with comparison circuit in linear constant-current circuit in the rear, the comparison circuit is provided with reference Signal input part, to access constant current reference voltage；

The comparison circuit is additionally provided with operational amplifier, and the reverse input end of the operational amplifier passes through a resistance (RB12) it is connected with the reference signal input；The positive input of the operational amplifier is connected with current feedback circuit.

Further, the current feedback circuit includes multiple constant current detection resistances, respectively resistance (RB5), resistance (RB6), resistance (RB7), resistance (RB8), resistance (RB9)；

Wherein, resistance (RB6), resistance (RB7), resistance (RB8) constitute parallel circuit, the electricity in parallel with resistance (RB9) The one end on road is connected on one end of resistance (RB5), the other end ground connection of the parallel circuit；The other end of resistance (RB5) connects It is connected on the normal phase input end of the operational amplifier.

Further, the current feedback circuit also includes electric capacity (CB5)；One end ground connection of the electric capacity (CB5) is another End is connected on the normal phase input end of the operational amplifier.

Preferably, the comparison circuit also includes a clamp diode；

The minus earth of the clamp diode；The anode of the clamp diode is connected with the switching tube (QB1), bag Include：When the switching tube (QB1) is audion, the anode of the clamp diode is connected with the emitter stage of the audion； When the switching tube (QB1) is field-effect transistor, the source of the anode of the clamp diode and the field-effect transistor Pole connects.

Further, the DC-DC voltage regulator circuits are liter voltage regulator circuit or reduction regulation circuit.

In a kind of attainable mode, when the DC-DC voltage regulator circuits are to rise voltage regulator circuit, including：With Inducer (LB801), on-off circuit, voltage conversion chip and its peripheral circuit that the second power supply outfan connects, and Output filter circuit；

The on-off circuit is connected with inducer (LB801) outfan, by the voltage signal of the described second power supply outfan Transmit and stable voltage signal is adjusted to into voltage conversion chip；Stable electricity after the on-off circuit is by regulation again After pressure signal transmission is filtered to the output filter circuit, there is provided be powered to TV SKD；

The voltage conversion chip is provided with a pulse-width signal end；The pulse-width signal end passes through resistance (RB801) it is connected with the reference signal input.

The voltage stabilizing backlight control circuit of described low-power consumption, also including a control master chip；

The control master chip is defeated with the control signal input, the reference signal input, the voltage detecting Go out end to connect respectively；

The control master chip adjusts the output to the control signal according to the change in voltage of the voltage acquisition outfan The signal magnitude of input and the reference signal input, with control the front end power circuit first power supply outfan, The output voltage values of the second power supply outfan, regulation flows through the constant current signal of LED string.

In a kind of attainable mode, the voltage detecting circuit includes diode (DB2) and resistance (RB18)；Its In, the negative electrode of diode (DB2) is connected on the negative electrode of the LED string；The anode of diode (DB2) is connected to resistance (RB18) on one end, the other end of resistance (RB18) accesses high level；

When the LED string is opened, diode (DB2) conducting, the voltage detecting circuit is examined by diode (DB2) The running voltage of the LED string is measured, so as to control the feedback circuit adjustment the first power supply outfan, the second power supply The output voltage of outfan；When the LED string is closed, diode (DB2) reversely ends, and shut-off flows through the LED string Electric current.

Further, the voltage detecting circuit also includes resistance (RB16)；One end of resistance (RB16) and diode (DB2) anode connection, the other end connects the voltage acquisition outfan.

The voltage detecting circuit also includes diode (DB3)；

The anode of the diode (DB3) is connected with the anode of diode (DB2)；The negative electrode of the diode (DB3) connects Connect the voltage acquisition outfan.

In another attainable mode, the voltage detecting circuit includes Regulate signal input；

The voltage detecting circuit, when the LED string is turned on, is incited somebody to action according to the level value of the Regulate signal input Switching tube (QB1) is gathered and exported with the magnitude of voltage of the junction of the LED string；When the LED string is closed, shut-off stream The electric current of LED string described in Jing.

Further, the control master chip is also connected with the Regulate signal input；

The control master chip enters according to the on off state of the LED string to the level value of the Regulate signal input Row synchronization control, including：When LED string is opened, the level value of the Regulate signal input is adjusted to into high level, when When LED string is turned off, the level value of the regulation input is adjusted to into low level；And by the reference signal input to The rear end linear constant current circuit is input into the constant current reference voltage.

Further, the voltage detecting circuit includes a switching tube (QB3), resistance (RB19) and resistance (RB20)；

When switching tube (QB3) is audion, the colelctor electrode of switching tube (QB3) is connected to the switching tube (QB1) and institute State on the junction of LED string；The emitter stage of switching tube (QB3) is connected with one end of resistance (RB19), resistance (RB19) it is another One end is used as voltage detecting outfan；The base stage of switching tube (QB3) is connected with one end of resistance (RB20), resistance (RB20) it is another One end is used as the Regulate signal input；

When switching tube (QB3) is field-effect transistor, the drain electrode of switching tube (QB3) is connected to the switching tube (QB1) On the junction of the LED string；The source electrode of switching tube (QB3) is connected with one end of resistance (RB19), resistance (RB19) The other end is used as the voltage acquisition outfan；The grid of switching tube (QB3) is connected with one end of resistance (RB20), resistance (RB20) the other end is used as the Regulate signal input.

Yet further, the voltage detecting circuit also includes a switching tube (QB4), resistance (RB21), resistance (RB22) With resistance (RB23)；Wherein, one end of resistance (RB21) is connected on the junction of switching tube (QB1) and LED string, the other end It is connected on the junction of switching tube (QB3) and resistance (RB20)；

When switching tube (QB4) is audion, the emitter stage of switching tube (QB4) is connected to ground；The base stage of switching tube (QB4) It is connected to ground by resistance (RB22)；The base stage of switching tube (QB4) is also used as the Regulate signal input by resistance (RB23) End；The colelctor electrode of switching tube (QB4) is connected by resistance (RB20) with switching tube (QB3), including：When switching tube (QB3) is three During pole pipe, the colelctor electrode of switching tube (QB4) is connected with the base stage of switching tube (QB3)；When switching tube (QB3) is field effect transistor, The colelctor electrode of switching tube (QB4) is connected with the source electrode of switching tube (QB3)；

When switching tube (QB4) is field effect transistor, the source electrode of switching tube (QB4) is connected to ground；The grid of switching tube (QB4) It is connected to ground by resistance (RB22)；The grid of switching tube (QB4) is also used as the Regulate signal input by resistance (RB23) End；The drain electrode of switching tube (QB4) is connected by resistance (RB20) with switching tube (QB3), including：When switching tube (QB3) is three poles Guan Shi, the drain electrode of switching tube (QB4) is connected with the base stage of switching tube (QB3)；When switching tube (QB3) is field effect transistor, switch The drain electrode of pipe (QB4) is connected with the source electrode of switching tube (QB3).

On the other hand, present invention also offers a kind of adaptation power supply adjust television set, including：TV SKD, the back of the body Light LED string, and the as above voltage stabilizing backlight control circuit of the low-power consumption described in any one；

The voltage stabilizing backlight control circuit is connected respectively with the TV SKD and the backlight LED light string, for When turning on the power supply of the television set, according to the running voltage of the backlight LED light string, Automatic adjusument supplies the television set The voltage signal of mainboard, the backlight LED light string；When the power supply of the television set is closed, shut-off flows through the backlight LED light The electric current of string.

The voltage stabilizing backlight control circuit of the low-power consumption that the present invention is provided, by front end power circuit duplex feeding output is provided End, the first power supply outfan is used to be powered to LED backlight；Second power supply outfan is connected with DC-DC voltage regulator circuits, will The voltage signal that second power supply outfan is exported is adjusted to after fixed voltage signal, is exported to mainboard and is powered, it is ensured that It is supplied to the voltage stability of mainboard；It is constant current that rear end linear constant current circuit is used to control the electric current for flowing through backlight LED light string Signal；The on off state that voltage detecting circuit passes through outside Regulate signal real-time control switching tube (QB3) of access, it is ensured that in backlight During unlatching, voltage acquisition outfan can collect the magnitude of voltage of LED string and switching tube (QB1) junction；Close in backlight When, switching tube (QB3) and switching tube (QB4) synchronously end, therefore LED string two ends are equivalent to open circuit, LED without glimmer phenomenon, Avoid unnecessary power consumption penalty and improve the service life of backlight LED.Present invention also offers a kind of adaptation power supply is adjusted Television set, as a result of the voltage stabilizing backlight control circuit of the low-power consumption after improvement, thus using the voltage stabilizing backlight control When circuit is powered to TV SKD and backlight of television LED string, above-described beneficial effect is equally reached, Improve the work efficiency of TV SKD and the service life of backlight LED.

Description of the drawings

Fig. 1 is a kind of schematic diagram of Heising modulation circuit that prior art is provided.

Fig. 2 is the structural representation of the constant current with one embodiment of controlling circuit of voltage regulation of the low-power consumption that the present invention is provided.

Fig. 3 is the physical circuit schematic diagram of a kind of achievable mode of the front end power circuit that the present invention is provided.

Fig. 4 is a kind of physical circuit schematic diagram of the front end power circuit that the present invention is provided.

Fig. 5 is a kind of circuit theory diagrams of the DC-DC voltage regulator circuits that the present invention is provided when being liter voltage regulator circuit.

Fig. 6 is the circuit theory diagrams of a kind of achievable mode of the rear end linear constant current circuit that the present invention is provided.

Fig. 7 is the structural representation of one embodiment of the voltage stabilizing backlight control circuit of the low-power consumption that the present invention is provided.

Fig. 8 is the physical circuit figure of the first embodiment of the voltage detecting circuit that the present invention is provided.

Fig. 9 is the physical circuit figure of second embodiment of the voltage detecting circuit that the present invention is provided.

Figure 10 is the physical circuit figure of the third embodiment of the voltage detecting circuit that the present invention is provided.

Figure 11 is the physical circuit figure of the 4th kind of embodiment of the voltage detecting circuit that the present invention is provided.

Figure 12 is the structural representation of the constant current with another embodiment of controlling circuit of voltage regulation of the low-power consumption that the present invention is provided Figure.

Figure 13 is the structural representation of another embodiment of the voltage stabilizing backlight control circuit of the low-power consumption that the present invention is provided.

Specific embodiment

Below in conjunction with the accompanying drawing in the embodiment of the present invention, the technical scheme in the embodiment of the present invention is carried out clear, complete Site preparation is described.

The present invention is described by taking LED television mainboard with LED backlight as an example to specific embodiment, needs explanation , the present invention is provided or improved various circuits are applicable in itself various mainboards to be powered and LED.

It is that the constant current of the low-power consumption that the present invention is provided is shown with the structure of one embodiment of controlling circuit of voltage regulation referring to Fig. 2 It is intended to.

In the present embodiment, the constant current of described low-power consumption includes front end power circuit 101, DC- with controlling circuit of voltage regulation D/C voltage adjusts circuit 102 and rear end linear constant current circuit 103.

The front end power circuit 101 includes the power supply outfan OUT1 of power supply circuits 1011, first, the second power supply outfan OUT2 and feedback circuit 1012；

Wherein, the feedback circuit 1012 includes feedback input end A_in, control signal input Cont and feedback signal Outfan B_out；The feedback input end A_in is connected with the described second power supply outfan OUT2, the feedback signal output B_out is connected with the power supply circuits 1011；Voltage of the feedback circuit 1012 according to control signal input Cont Value, to the output feedback signal of the power supply circuits 1011, to control the first power supply outfan of the power supply circuits 1011 pairs The magnitude of voltage of OUT1 and the second power supply outfan OUT2 is adjusted.

When being embodied as, the LED string that the present embodiment is provided is preferably backlight of television LED string, and supplies by first Electricity output end OUT1 is powered；The mainboard is preferably TV SKD, and is supplied by the second power supply outfan OUT2 Electricity；

It is the physical circuit schematic diagram of a kind of achievable mode of the front end power circuit that the present invention is provided referring to Fig. 3.

In a kind of achievable mode, as shown in figure 3, feedback circuit 1012 can be provided with optocoupler PCB101, manostat UB102 And its peripheral circuit.Wherein, the optocoupler PCB101 includes being located at light emitting diode (the i.e. He of foot 1 of optocoupler PCB101 of former limit The component of foot 2) and positioned at the optical signal converter (i.e. the component of the foot 3 of optocoupler PCB101 and foot 4) of secondary.

Manostat UB102 by the control signal that the control signal input is input into access to optocoupler PCB101 positioned at original The light emitting diode on side；Control signal is converted to the light emitting diode position that the optocoupler PCB101 is transferred to after optical signal In the optical signal converter of secondary；The optical signal converter converts optical signals to export after the signal of telecommunication to the feedback signal Outfan.

Further, the feedback circuit 1012 is additionally provided with resistance RB131 and resistance RB132；The one of the resistance RB131 Hold as the feedback input end, the other end is connected with the anode of the light emitting diode positioned at former limit of optocoupler PCB101；The electricity One end of resistance RB132 is connected to the anode of the light emitting diode, and the other end is connected on the negative electrode of the light emitting diode.

Wherein, the input (foot 1) positioned at the light emitting diode of former limit is used as feedback input end A_in by resistance RB131 It is connected with the second power supply outfan OUT2, and the former limit two ends (foot 1 and foot 2) of optocoupler PCB101 are in parallel with resistance RB132；It is located at Outfan (foot 4) connection of the optical signal converter of the secondary of optocoupler PCB101 is used as feedback signal output B_out and power supply The feedback control end feedback connections of circuit 1011, the other end (foot 3) ground connection of optical signal converter.It should be noted that Necessary electronic component in resistance RB132 feedback circuits not in the present embodiment.

Manostat UB102 preferably adopts adjustable precision shunt manostat, including negative electrode K, anode A and reference input R, And the reference voltage of built-in 2.5V (volt), specifically, the manostat of model TL431 can be adopted to be realized.Wherein, it is described can The anode A ground connection of debugging precision shunt manostat, the light emitting diode positioned at former limit of the negative electrode K and optocoupler PCB101 connects Connect；Reference input R is used to access the control signal of control signal input Cont.

Further, the feedback circuit 1012 is additionally provided with voltage stabilizing feedback circuit.

In a kind of attainable mode, the voltage stabilizing feedback circuit includes electric capacity CB109 and resistance RB133；The electricity The one end for holding CB109 is connected on the negative electrode K of the adjustable precision shunt manostat, one end of the other end and resistance RB133 Series connection；The other end of resistance RB133 is connected on the reference input R of the adjustable precision shunt manostat.

In another kind of attainable mode, the voltage stabilizing feedback circuit includes electric capacity CB110；The electric capacity CB110's One end is connected on the negative electrode K of the adjustable precision shunt manostat, and it is steady that the other end is connected to the adjustable precision shunt On the reference input R of depressor.

Further, the present embodiment can be combined both the above implementation, to realize the voltage stabilizing feedback electricity Road.I.e. described voltage stabilizing feedback circuit is provided with electric capacity CB109, resistance RB133 and electric capacity CB110 simultaneously.

As shown in figure 3, the negative electrode K of manostat UB102 is connected with the foot of light emitting diode 2 of optocoupler PCB101 former limits, voltage stabilizing The anode A 0 of device UB102 is grounded；One end of resistance RB134 is connected with the reference input R of manostat UB102, other end ground connection； One end of electric capacity CB109 is connected on the negative electrode K of the adjustable precision shunt manostat, the other end and the one of resistance RB133 End series connection；The other end of resistance RB133 is connected on the reference input R of the adjustable precision shunt manostat；The electricity The one end for holding CB110 is connected on the negative electrode K of the adjustable precision shunt manostat, and the other end is connected to the adjustable essence On the reference input R of close shunt regulator.

Further, the reference input R of the adjustable precision shunt manostat is by a potentiometer and the control Signal input part connects.In this embodiment, it is preferred that, the potentiometer is resistance RB150.

As shown in figure 3, electric capacity CB109 one end is connected with 2 feet of optocoupler PCB101, after the other end is connected with resistance RB133 It is connected with one end of resistance RB150, the other end of resistance RB150 is used as control signal input Cont；Electric capacity CB110's One end is connected with the negative electrode K of manostat UB102, and the other end is connected with the reference input R of manostat UB102；Resistance RB135's One end is connected with feedback input end A_in, and the other end is connected with the reference input R of manostat UB102.Thus, feedback is constituted A kind of specific embodiment of circuit 1012.

In the present embodiment, increase by a resistance RB150 on the reference input R of manostat UB102, while by control Signal input part Cont introduces a control signal and carries out Automated condtrol to the output voltage values of the negative electrode K of manostat UB102, from And it is capable of achieving the regulation to power supply circuits 1011 and its output voltage.

It is a kind of physical circuit schematic diagram of the front end power circuit that the present invention is provided referring to Fig. 4.

Wherein, the power supply circuits 1011 include power supply input circuit 11, switching power circuit 12, multiple-channel output transformator TB101, LED power output circuit 13 and main board power supply output circuit 14.

The power supply input circuit 11 under the control of the switching power circuit 12 by the power supply signal of access transmit to The multiple-channel output transformator TB101；As shown in figure 4, the multiple-channel output transformator TB101 includes main winding and auxiliary winding. Wherein, the coil of 9 foot～11 feet of multiple-channel output transformator TB101 forms primary main winding, multiple-channel output transformator TB101's The coil of 1 foot～2 foot forms secondary main winding；The coil of 7 foot～8 feet of multiple-channel output transformator TB101 formed it is primary secondary around Group, the coil of 1 foot～6 foot of multiple-channel output transformator TB101 forms secondary auxiliary winding, wherein, based on the coil of 1 foot～2 foot The shared winding of winding and time winding, it should be noted that can be with common sparing winding between secondary main winding and auxiliary winding, it is also possible to Using independent winding.When being embodied as, the main winding will transmit defeated to the main board power supply after the power supply signal transformation Go out circuit 14, and exported by the described second power supply outfan OUT2；The auxiliary winding synchronously becomes the power supply signal Transmit after pressure to the LED and power output circuit 13, and exported by the described first power supply outfan OUT1；Therefore, Fig. 4 In multiple-channel output transformator TB101 there is two output voltage.

Especially, in technical field of television sets, the first power supply outfan OUT1 preferably supplies the power supply of LED backlight Outfan, the second power supply outfan OUT2 preferably supplies the power supply outfan of TV SKD.

In the present embodiment, output voltages of the multiple-channel output transformator TB101 per circle coil is identical, when changing wherein Output voltage all the way, then the output voltage on another road also will synchronously follow change.For example, the coil of main winding is 2 circles, Output voltage is 12V, i.e., the output voltage per circle coil is 6V；The output voltage for assuming auxiliary winding is 120V, then auxiliary winding Coil turn is 20 circles.And the coil turn of main winding and auxiliary winding can be adjusted according to practical application, i.e., described master Winding is 1 with the coil ratio of the auxiliary winding：N, N ＞ 0, i.e., when main winding output voltage be V1 when, auxiliary winding it is defeated Go out voltage for V2=N*V1.

It should be noted that the feedback input end A_in of feedback circuit 1012 can connect the first of the power supply circuits 1011 The power supply outfan OUT2 of power supply outfan OUT1 or second, have no effect on the enforcement of the present embodiment.

The external control letter that the present invention can be accessed by control signal input Cont of linear regulation feedback circuit 1012 Number size, so as to control the first power supply outfan OUT1 or second power supply outfan OUT2 magnitude of voltage.Specifically, with described The feedback input end A_in of feedback circuit 1012 is connected to as a example by the second power supply outfan OUT2 of the power supply circuits 1011, this The basic functional principle of embodiment is mainly：

When the output voltage of power supply circuits 1011 is raised, (the first power supply outfan OUT1 and the second power supply outfan OUT2 are same When Shi Shenggao), the control signal of control signal input Cont is through resistance RB135 and resistance RB134, resistance RB150 partial pressures Voltage afterwards is transmitted to the reference input R of manostat UB102, and manostat UB102 is by the signal value of reference input R and its Portion's reference voltage is compared.When the signal value of reference input R is more than reference voltage, between manostat UB102 anode and cathodes Voltage reduce, and then optocoupler PCB101 electric current increase, dynamic electric resistor diminishes between optocoupler PCB101 colelctor electrodes and emitter stage (4 feet of the current collection of optocoupler PCB101 extremely optocoupler, 3 feet of transmitting extremely optocoupler), the voltage between colelctor electrode and emitter stage becomes It is low；The feedback foot of PWM (Pulse Width Modulation, pulse width modulation) the control chip UB101 for connecting therewith The level step-down of COMP, pwm chip UB101 output duty cycles reduce, so that multiple-channel output transformator TB101's is defeated Go out voltage reduction.Conversely, when the signal value of reference input R is less than reference voltage, multiple-channel output transformator TB101 can be caused Output voltage (including first power supply outfan OUT1 and second power supply outfan OUT2 output voltage) raise.Therefore, surely The magnitude of voltage of the reference input R of depressor UB102 determines the output voltage of multiple-channel output transformator TB101.

Therefore, based on principles above, to reach the voltage signal that the reference input R for adjusting manostat UB102 is accessed , so as to control the purpose of the output voltage of transformator TB101, the present invention is by increasing resistance RB150 and in resistance RB150 for size Side incoming control signal realizing.Specifically, when the output voltage for needing to modulate the second power supply outfan OUT2, and voltage stabilizing When the internal reference voltage of device UB102 is 2.5V, the output voltage values computing formula of the second power supply outfan is：Vout2=bases Quasi- voltage * (1+R135/R134), wherein, reference voltage is preferably 2.5V.Preferably, can be by external control chip output one Individual PWM_12V signals to control signal input Cont, via resistance RB150 by PWM_12V signal transmissions to resistance Series connection point (i.e. the reference input R of manostat UB102) between RB134 and resistance RB135.

When being embodied as, the PWM_12V signals of control signal input Cont can adopt any one perseverance in 0-3.3V Determine magnitude of voltage, or, using PWM (Pulse Width Modulation, the pulse width modulation) ripple of certain waveform.According to The output voltage values computing formula of two power supply outfans：Vout2=reference voltage * (1+R135/R134), under any circumstance, When by control signal input Cont from external control chip to feedback circuit 1012 be input into control signal be 3.3V (most When greatly), the output voltage of the second power supply outfan OUT2 is minimum, because the input voltage of control signal input Cont (3.3V) more than manostat UB102 reference voltage 2.5V (circuit stability work when manostat UB102 1 foot voltage and Reference voltage is almost equal), so be the equal of now that resistance RB150 is connected on the power supply of 3.3V, that is, equivalent to by electricity Resistance RB150 has been connected in parallel on resistance RB135, according to the voltage equation of Vout2 iting can be seen from, due to resistance RB135 parallel connection resistance RB150, the equivalent resistance equivalent to resistance RB135 is reduced, so that output voltage Vout2 is reduced.When by external control core Control signal input Cont from piece to feedback circuit 1012 be input into control signal be 0V (minimum) when, second power outfan The output voltage of OUT2 is maximum, because equivalent to ground connection when the control signal of control signal input Cont input is 0V, this When equivalent to resistance RB150 has been connected in parallel on resistance RB134, according to above-mentioned voltage computing formula, due to resistance RB134 it is in parallel Resistance RB150, the equivalent resistance equivalent to resistance RB135 diminishes, so that output voltage Vout2 is raised.

It can be seen that, by the control signal of the control signal input Cont input of linear regulation feedback circuit 1012 (for example The constant voltage signal or PWM ripples of above-mentioned 0V～3.3V), the output voltage of the second power supply outfan OUT2 can be caused in reality (Vout2_max=12.5V, Vout2_min=11.5V) is adjusted between common voltage scope 11.5V～12.5V, so as to Realize fine setting；In the same manner, in the presence of multiple-channel output transformator TB101, the output voltage of the first power supply outfan OUT1 also will Realize that synchronous automatic adaptation is adjusted, especially, the output voltage for supplying TV motherboard circuit often changes 0.01V, supplies LED string Output voltage will change 0.1V.

In concrete application occasion, under product ideal case (power supply circuits output is reduced), can be by outside linear regulation Portion's control chip to the control signal that control signal input Cont of feedback circuit 1012 is input into is high level (such as 3.3V), from And the second of power supply circuits 1011 voltages for powering outfan OUT2 outputs can be made to be minimum output voltage, it is possible to reduce television set The stand-by power consumption of mainboard.

Additionally, the LED string to be powered is in series by multiple LEDs, with the quantity of LED string to be powered Increase, required supply voltage constantly increases after multiple LED strip connection, it is therefore desirable to the output of the first power supply outfan OUT1 Voltage can adaptively respond the number change of LED, automatically adjust its output voltage values.

The the first power supply outfan OUT1 and the second power supply outfan OUT2 provided due to the present embodiment belongs to a change Depressor TB101, when the output voltage to the first power supply outfan OUT1 is adjusted, will necessarily be to the second power supply outfan The output voltage of OUT2 produces impact, and vice versa.And the supply voltage of TV SKD is typically more fixed (about 12V), if The output voltage amplitude fluctuation of the second power supply outfan OUT2 is excessive, it will affect the overall performance of TV SKD, and too high Supply voltage possibly even burn TV SKD.

As shown in Fig. 2 the constant current of the low-power consumption of present invention offer is additionally provided with DC-DC voltage-regulation electricity with controlling circuit of voltage regulation Road 102.Specifically, the input of the DC-DC voltage regulator circuits 102 is connected with the described second power supply outfan OUT2, uses In the voltage signal that the described second power supply outfan OUT2 is exported is adjusted to after fixed voltage signal, export to television set Mainboard is powered.

So that supply voltage needed for TV SKD is as 12V as an example, the present embodiment is in front end power circuit 101 and TV owner Increase one-level DC-DC voltage regulator circuit 102 between plate, by the response of DC-DC voltage regulator circuits 102 second power supply outfan The change of the output voltage of OUT2, automatically adjusts the voltage value exported to TV SKD.DC-DC voltage regulator circuits 102 situations that can be more than or less than 12V according to the output voltage of the second power supply outfan OUT2, using reduction regulation circuit Or liter voltage regulator circuit.

It is a kind of circuit theory of DC-DC voltage regulator circuits that the present invention is provided when being liter voltage regulator circuit referring to Fig. 5 Figure.Specifically, when the DC-DC voltage regulator circuits 102 are to rise voltage regulator circuit, including：Electricity output is supplied with described second Inducer LB801, on-off circuit 1021, voltage conversion chip UB801 and its peripheral circuit 1022 that end OUT2 connects, and it is defeated Go out filter circuit 1023.In the present embodiment, by the way that the output voltage of the second power supply outfan OUT2 is adjusted using the boosting of Fig. 5 Economize on electricity road obtains 12.5Vout and is powered to TV SKD after being boosted.

The on-off circuit 1021 is connected with inducer LB801 outfans, by the electricity of the described second power supply outfan OUT2 Pressure signal transmission is adjusted to stable voltage signal into voltage conversion chip UB801；Again will by the on-off circuit 1021 Stable voltage signal after regulation is transmitted to the output filter circuit 1023 after being filtered, there is provided entered to TV SKD Row power supply.

In order to realize the output voltage of the power supply outfan OUT1 of Automatic adjusument first, while ensureing supply TV SKD Voltage signal stability, it is defeated that the present embodiment realizes the second power supply after it with the addition of DC-DC voltage regulator circuits 102, then Go out to hold the adjustability of the output voltage of OUT2.The operating voltage range that TV SKD is allowed is usually 11.5V～12.5V, then DC-DC voltage regulator circuits 102 start after effect be by second power supply outfan OUT2 output voltage be adjusted after 12.5Vout outfans export the voltage signal of 11.5V～12.5V, so that connect with LED series winding first supplies electricity output The output voltage of end OUT1 can be adjusted according to actual LED lamp bar quantity, improve the control electricity that the present embodiment is provided The scope of application on road and motility.

Described constant current is additionally provided with rear end linear constant current circuit 103 with controlling circuit of voltage regulation, specifically, as shown in Fig. 2 institute Rear end linear constant current circuit 103 is stated including comparison circuit 1031 and constant-current control circuit 1032；The comparison circuit 1031 is provided with Reference signal input PWM_REF, to access constant current reference voltage V_REF；The constant-current control circuit 1032 is electric in the comparison It is connected with one end LED- of LED string to be powered under the regulation on road 1031, the other end LED+ of the LED string to be powered and institute State the first power supply outfan OUT1 connections；

Voltage acquisition output all the way is drawn in the constant-current control circuit 1032 with the LED string junction P to be powered Hold (such as output terminals A DC_12V in Fig. 2), with according to the change in voltage of the LED string to be powered, the front end power circuit Adjust the magnitude of voltage of control signal input Cont, so as to control it is described first power supply outfan OUT1, second power supply it is defeated Go out to hold the output voltage of OUT2.

It is the circuit theory diagrams of a kind of achievable mode of the rear end linear constant current circuit that the present invention is provided referring to Fig. 6.

When being embodied as, in the rear in linear constant-current circuit 103, the comparison circuit 1031 also includes operation amplifier The inverting input of device UB1A, the operational amplifier UB1A passes through a resistance RB12 and reference signal input PWM_ REF connects；The normal phase input end of the operational amplifier UB1A is connected with current feedback circuit.Specifically, as shown in fig. 6, should Current feedback circuit includes multiple constant current detection resistances, respectively resistance RB5, resistance RB6, resistance RB7, resistance RB8, resistance RB9；Wherein, resistance RB6, resistance RB7, resistance RB8 and resistance RB9 composition parallel circuit, one end connection of the parallel circuit On one end of resistance RB5, the other end ground connection of the parallel circuit；The other end of resistance RB5 is connected to the operation amplifier On the normal phase input end of device.Further, the current feedback circuit also includes electric capacity CB5；One termination of the electric capacity CB5 Ground, the other end is connected on the normal phase input end of the operational amplifier.The circuit of wherein resistance RB5 and electric capacity CB5 compositions can It is filtered with the signal of the normal phase input end to being input to operational amplifier UB1A.Preferably, the comparison circuit 1031 is gone back Including a clamp diode DB1, to protect the normal work of the comparison circuit 1031.

The rear end linear constant current circuit 103 also includes a switching tube QB1.Switching tube QB1 can be audion or MOS (Metal-Oxid-Semiconductor, metal-oxide semiconductor (MOS)) field-effect transistor, abbreviation metal-oxide-semiconductor or field effect transistor Pipe.Wherein, the conduction and cut-off state of switching tube QB1 is associated with the physical characteristics of its own.For example, when switching tube QB1 is three During pole pipe, according to the VA characteristic curve of audion, saturation region, amplification region and cut-off region are there is, audion is sent out respectively Voltage signal between emitter-base bandgap grading and colelctor electrode produces different impacts, such as when triode operation is in saturation region, audion Equivalent to short-circuit (conducting state) between emitter-base bandgap grading and colelctor electrode.

In the present embodiment, when the switching tube QB1 is audion, the constant-current control circuit 1032 passes through described three The colelctor electrode of pole pipe is connected with one end (LED-) of the LED string to be powered；The emitter stage of the audion and the clamper The anode connection of diode DB1；When the switching tube QB1 is field-effect transistor, the constant-current control circuit 1032 passes through The drain electrode of the field-effect transistor is connected with one end (LED-) of the LED string to be powered；The field-effect transistor Source electrode is connected with the anode of the clamp diode DB1.

When being embodied as, the minus earth of clamp diode DB1, anode is connected to operational amplifier by resistance RB5 The normal phase input end of UB1A.After rear end linear constant current circuit 103 starts, through the adjustment of operational amplifier UB1A, its positive Input connects magnitude of voltage and its constant current reference voltage V that reversely input is accessed that constant current detection resistance is got_REFIt is equal, Then as constant current reference voltage V_REFDuring turn-on voltage (about 0.7V) higher than clamp diode DB1, clamp diode DB1 will Conducting ground connection, i.e., the voltage at the constant current detection resistance two ends for being composed in parallel by resistance RB6, resistance RB7, resistance RB8 and resistance RB9 Value is clamped diode DB1 and is limited, therefore, clamp diode DB1 serves certain protective effect.

Also, due to the emitter stage (switching tube QB1 is audion) or source electrode (switching tube QB1 is metal-oxide-semiconductor) of switching tube QB1 It is connected with the anode of clamp diode DB1, therefore the constant current value of the switching tube QB1 that circulates can be calculated by below equation：

As constant current reference voltage V_REFDuring turn-on voltage higher than clamp diode DB1, the constant current of the switching tube QB1 that circulates Signal is I_{Constant current}The resistance of the turn-on voltage of=DB1/constant current detection resistance；As constant current reference voltage V_REFLess than clamp diode During the turn-on voltage of DB1, the constant current signal of the switching tube QB1 that circulates is I_{Constant current}=constant current reference voltage V_REF/ constant current detection resistance Resistance.Generally, the turn-on voltage of clamp diode DB1 is 0.7V, and the resistance of constant current detection resistance is resistance RB6, resistance Equivalent resistance after RB7, resistance RB8 and resistance RB9 are in parallel.

In the present embodiment, the first power supply outfan is connected to the positive pole LED+ of LED string, by the perseverance of switching tube QB1 Flow control, then constant current detection resistance (parallel resistance of resistance RB6, resistance RB7, resistance RB8 and resistance RB9) is concatenated to ground, it is permanent The size of current of LED string is converted into voltage signal and is linked into operational amplifier UB1A and constant current reference voltage by stream detection resistance V_REF(it is controlled by outside master chip, or accesses fixed voltage, if the constant current value I that fixed voltage is then exported_{Constant current}It is then solid Definite value, it is impossible to carry out the regulation of constant current size) it is compared and amplifies, so as to controlling switch pipe QB1 adjusts the electric current of LED string Keep constant.

When being embodied as, LED string typically can connect plurality of LEDs lamp, wherein the running voltage of single LEDs is generally 2.8V ～3.4V, the running voltage after the series connection of plurality of LEDs lamp will accordingly increase.So that switching tube QB1 is as metal-oxide-semiconductor as an example, switching tube QB1's Drain and the voltage between source electrode is：V_DS=V_OUT1- LED string running voltage-constant current reference voltage V_REF.Therefore, back end of line Property constant-current circuit 103 enter working condition after, the voltage V between the drain electrode of switching tube QB1 and source electrode_DSLED string will be subject to Running voltage size impact, the crossmodulation of multiple-channel output transformator TB101 is may also be subjected in addition, and (general range is 7%) impact.

With the change of LED string voltage, the drain-source voltage V of switching tube QB1_DSVoltage also synchronously changes, switching tube This Partial Power (V of QB1_DS* constant current value I_{Constant current}) form that will be converted into heat comes out, V_DSVoltage is bigger, switching tube The power consumption of QB1 is bigger, and temperature is higher.Therefore the excessive switching tube QB1 of power consumption can reduce power-efficient and cause switching tube QB1 It is overheated and be easily damaged.In order to reduce the power consumption and temperature of switching tube QB1, can make using multiple metal-oxide-semiconductors or audion are in parallel Use for switching tube QB1, but this technical scheme result in the increase of cost.For this purpose, the present embodiment is to the linear Constant Electric Current in rear end Make further improvement in road 103.

The embodiment of the present invention combines Fig. 2～Fig. 6, there is provided a kind of constant current of low-power consumption and controlling circuit of voltage regulation, can solve The power problemses of above-described switching tube QB1.Specifically, the present embodiment by the constant-current control circuit 1032 with it is described LED string junction P to be powered draws voltage acquisition output terminals A DC_12V all the way, with the electricity of real-time detection LED string to be powered Buckling, is that the pressure drop between voltage acquisition output terminals A DC_12V and reference signal input PWM_REF sets a threshold value, Or, it is that the output voltage of voltage acquisition output terminals A DC_12V sets a steady state value (reference signal input PWM_REF Voltage V_REFIt is typically small), when the pressure drop between voltage acquisition output terminals A DC_12V and reference signal input PWM_REF is more than The threshold value, or the output voltage of voltage acquisition output terminals A DC_12V be more than the steady state value when, by adjust front end power supply Control signal PWM_12V of control signal input Cont in circuit 101, controls optocoupler PCB101 by the work of LED string The situation of change (the change in voltage situation of the i.e. first power supply outfan OUT1) of voltage feeds back to pwm chip UB101, PWM Control chip UB101 controlling switch pipes QB101 changes dutycycle, so that the magnitude of voltage of voltage acquisition output terminals A DC_12V The magnitude of voltage of reference signal input PWM_REF is deducted equal or close to the default threshold value (or voltage acquisition outfan The magnitude of voltage of ADC_12V is equal or close to the steady state value), therefore, the present embodiment can pass through control signal input Cont Control signal PWM_12V, stop voltage collection output terminals A DC_12V and reference signal input PWM_REF between pressure drop, So as to reduce the drain-source voltage V of switching tube QB1_DSAffected by the change in voltage of LED string, reduced the power consumption of switching tube QB1 With ensure that power-efficient.

In the present embodiment, due to first power supply outfan OUT1 and second power supply outfan OUT2 output voltage by Multiple-channel output transformator TB101 is exported, then reduced above by control signal PWM_12V of control signal input Cont While the power consumption of switching tube QB1, the voltage that will necessarily cause all output windings of multiple-channel output transformator TB101 changes Become (also will change to the second output voltage for powering outfan OUT2 that TV SKD is powered), but, due to this Embodiment is provided with DC-DC voltage regulator circuits 102, therefore this enforcement between the second power supply outfan OUT2 and TV SKD Example is prevented from causing the change model of TV SKD power supply because the output voltage adjustment to front end power circuit is excessive Enclose excessive situation to occur, and DC-DC voltage regulator circuits 102 can be according to practical situation using blood pressure lowering or booster circuit.

A kind of constant current of low-power consumption that the present invention is provided and controlling circuit of voltage regulation, are provided with front end power circuit, DC-DC electric Voltage regulator circuit and rear end linear constant current circuit, using front end power circuit the supply voltage of two-way output is adjusted, and in front end Feedback circuit is set up in power circuit, and is provided with control signal input in a feedback circuit, to realize controlling front end power supply Circuit is in the first power supply outfan and the voltage of the second power supply outfan；Because the voltage signal of control signal input will be same When affect the first output voltage for powering outfan and the second outfan, therefore the present invention further passes through DC-DC voltage-regulation Circuit being stablized to ensure to export to the voltage signal of motherboard circuit；And string is adapted to automatically by setting up rear end linear constant current circuit The change of the LED backlight quantity of connection, can adjust the control signal input according to the magnitude of voltage after LED backlight series connection Magnitude of voltage, so as to passing through front end power circuit and its feedback circuit control the first power supply outfan, second supplying electricity output The output voltage at end, and the first power supply outfan is connected to LED backlight and is powered, and realizes and LED backlight quantity phase The voltage automatization of adaptation is adjusted, the power consumption of reduction circuit switch element, and ensure that stablizing for the supply voltage of motherboard circuit Property.

In the present embodiment, because the voltage acquisition that the junction point of backlight LED light string and constant-current control circuit is drawn is exported When the LED operation voltage (analogue signal) for collecting is delivered to external control deviceses such as analog-digital converter by end ADC_12V, electricity The voltage often higher (being more than 3.3V) of pressure collection output terminals A DC_12V, mismatching with the voltage of analog-digital converter can not be with it It is directly connected to.Therefore, one or more resistance are generally serially connected between voltage acquisition output terminals A DC_12V and analog-digital converter To greatly, the voltage signal after partial pressure is exported again to the input port of analog-digital converter.But, when closing television machine backlight electricity During source, the resistance for making its concatenation is produced current signal by the magnitude of voltage of voltage acquisition output terminals A DC_12V, and the current signal is passed through Voltage acquisition output terminals A DC_12V is moved back in LED string, due to LED string it is very sensitive to electric current, as long as there is faint electricity Stream can just be turned on and lighted, therefore, prevent backlight LED to send faint from complete switching off by the way of big resistance using concatenating Light, this phenomenon is not allowed for television set manufacture index request.Therefore need to backlight of television control circuit Further improved.

For this purpose, the embodiment of the present invention enters one on the basis of the constant current of previously described low-power consumption and controlling circuit of voltage regulation Step ground, by setting up a kind of voltage detecting circuit 104 being connected with rear end linear constant current circuit 103, to set up into a kind of low work( The voltage stabilizing backlight control circuit of consumption.

It is a kind of structure of one embodiment of the voltage stabilizing backlight control circuit of low-power consumption that the present invention is provided referring to Fig. 7 Schematic diagram.

The present embodiment provide low-power consumption voltage stabilizing backlight control circuit, above-described low-power consumption linear constant current with On the basis of stabilization control circuit, further, voltage detecting circuit 104 is additionally provided with.The voltage stabilizing backlight control of i.e. described low-power consumption Circuit processed includes：Front end power circuit 101, DC-DC voltage regulator circuits 102, rear end linear constant current circuit 103 and voltage detecting Circuit 104.Wherein, the voltage detecting circuit is used for：When switching tube QB1 conductings are detected, by the running voltage of LED string Collection output is to external control deviceses or chip；When switching tube QB1 cut-offs are detected, disconnect LED string and adopt with the voltage The connection of collection output terminals A DC_12V.

Specifically, the front end power circuit 101, DC-DC voltage regulator circuits 102, rear end linear constant current circuit 103 with Above and embodiment described in Fig. 2～Fig. 6 front end power circuit 101, DC-DC voltage regulator circuits 102, rear end linear constant current The basic structure of circuit 103 is identical with principle one-to-one corresponding, and detailed content refer to above, will not be described here.

The input of the voltage detecting circuit 104 is connected to the constant-current control circuit 1032 with the LED string Junction, the outfan of the voltage detecting circuit 104 is voltage detecting output terminals A DC, in LED string conducting When, the electricity of the constant-current control circuit 1032 and the junction of the LED string is exported by voltage detecting output terminals A DC Pressure value；When the LED string is closed, shut-off flows through the electric current of the LED string.

Preferably, the first power supply outfan OUT1 is connected with the anode (LED+) of LED string, for television set LED backlight is powered；The input of the DC-DC voltage regulator circuits 102 is connected with the described second power supply outfan OUT2, uses In the voltage signal that the described second power supply outfan OUT2 is exported is adjusted to after fixed voltage signal, export to television set Mainboard is powered；When being embodied as, DC-DC voltage regulator circuits 102 are added to cause the voltage of supply backlight LED light string adjustable Scope is wider, but still can keep exporting to the voltage signal of TV SKD and be relatively fixed, therefore the present embodiment can be Match with the television set of the 32 cun～scopes such as 42 cun in the case of hardware circuit need not be changed and use.

The switching tube QB1 of the rear end linear constant current circuit 103, be to the electric current of the LED string for controlled output Constant current signal；When the switching tube QB1 is audion, the colelctor electrode that the constant-current control circuit 1032 passes through the audion It is connected with the negative electrode (LED-) of the LED string；When the switching tube QB1 is field-effect transistor, the current constant control electricity Road 1032 is connected by the drain electrode of the field-effect transistor with the negative electrode (LED-) of the LED string.

In the present embodiment, described voltage detecting circuit 104 can be realized neatly using numerous embodiments.Tool Body ground, the input of voltage detecting circuit 104 be connected on the switching tube QB1 and junction P of LED string (i.e. with it is original ADC_12V ends connect), the outfan of voltage detecting circuit 104 as the present embodiment in " new voltage acquisition outfan ", or Referred to as voltage detecting output terminals A DC.

It is the physical circuit schematic diagram of the first embodiment of the voltage detecting circuit that the present invention is provided referring to Fig. 8.

In the first embodiment of the voltage detecting circuit 104, in the constant-current control circuit 1032 and LED Voltage acquisition voltage output end ADC_12V all the way is drawn in string junction (i.e. switching tube QB1 and LED string), with voltage inspection Slowdown monitoring circuit 104 connects；The voltage detecting circuit 104 includes diode DB2 and resistance RB18；Wherein, the negative electrode of diode DB2 It is connected on the negative electrode of the LED string；The anode of diode DB2 is connected on one end of resistance RB18, and resistance RB18's is another Access high level VCC (preferably 3.3V) in one end.When being embodied as, high level VCC can by with switching tube QB1 identicals control The constant-current control circuit 1032 of end control is provided.

When the LED string is opened, diode DB2 conductings, the voltage detecting circuit 104 is examined by diode DB2 Measure the running voltage of the LED string, so as to control the feedback circuit 1012 adjust it is described first power supply outfan OUT1, The output voltage of the second power supply outfan OUT2；When the LED string is closed, diode DB2 reversely ends, and shut-off flows through institute State the electric current of LED string.

The present embodiment is further provided with detector, for deriving the voltage signal of voltage acquisition output terminals A DC_12V.Its In, the input of the detector is connected with the anode of diode DB2, and the outfan of the detector is adopted as described voltage Collection output terminals A DC_12V (or referred to as voltage detecting output terminals A DC).

Specifically, as shown in figure 8, the detector can be preferably resistance RB16.One end of resistance RB16 and diode DB2 Anode connection, the other end is used as voltage acquisition output terminals A DC_12V (can be described as here voltage detecting output terminals A DC).

Output terminals A DC_12V and diode all the way are drawn in the junction P of constant-current control circuit 1032 and LED string negative electrode DB2 negative electrodes connect, and when the LED string is opened, diode DB2 conductings detect the LED string by diode DB2 Running voltage flow through resistance RB16 and transmit to external control deviceses or chip, so as to be adjusted by controlling the feedback circuit The output voltage of the first power supply outfan OUT1, the second power supply outfan OUT2；When the LED string is closed, that is, open When closing pipe QB1 cut-offs, diode DB2 reversely ends, and shut-off flows through the electric current of the LED string.

Preferably, the voltage detecting circuit 104 that the present embodiment is provided also includes a filter circuit of pressure-stabilizing 1042；It is described Filter circuit of pressure-stabilizing 1042 is connected with the detector output end, for when diode DB2 is turned on, by the detector 1041 Output signal be filtered after export.

Specifically, the voltage detecting circuit 104 is in the filter circuit of pressure-stabilizing 1042, also including resistance RB17；Institute One end ground connection of resistance RB17 is stated, the other end is connected in voltage detecting output terminals A DC.

Further, the voltage detecting circuit 104 also includes Zener diode D1, electric capacity CB7；And Zener diode D1 Negative electrode be connected as voltage detecting output terminals A DC jointly with one end of electric capacity CB7；The anode and electric capacity of Zener diode D1 The other end common ground of CB7.Wherein, the Main Function of Zener diode D1 is to prevent voltage detecting circuit 104 from working different Often or when switching tube QB1 is turned off cause the output voltage of port ADC excessive because high level VCC voltages are more than 3.3V, from And the situation for burning the device that voltage detecting output terminals A DC is connected occurs.Specifically, the low-power consumption of the present embodiment offer is steady Pressing the main operational principle of backlight control circuit is：

When backlight of television power supply is opened, switching tube QB1 conductings enter working condition, the P points that will be connect with LED series winding Voltage be limited in colelctor electrode (when switching tube QB1 be audion when) or drain electrode (when switching tube QB1 be field-effect transistor when) Magnitude of voltage (typically smaller than 3.3V) on, meanwhile, the access of high level VCC causes the junction point of diode DB2 and resistance RB18 Voltage V_AHigher than the voltage of P points, therefore, diode DB2 conductings, circuit passes through resistance RB18, diode DB2 and switching tube QB1 loops are operated.Now, the voltage V of the junction point of diode DB2 and resistance RB18_A=V_DB2+V_QB1；Now, voltage inspection Survey output terminals A DC output voltage be：V_ADC=V_A*RB17/(RB16+RB17).In closing television machine backlight electric power, switch Pipe QB1 enters cut-off state, and LED string two ends keep constant pressure and there are the high level much larger than 3.3V, therefore two at LED- ends Pole pipe DB2 is reversely ended, and open circuit, i.e. LED string are equivalent between LED string and voltage detecting circuit 104 will be without weak current Pass through, thus glimmer phenomenon will not be produced.

It is the physical circuit schematic diagram of second embodiment of the voltage detecting circuit that the present invention is provided referring to Fig. 9.

The distinctive points of second embodiment and its first embodiment of the voltage detecting circuit 104 are：Institute State detector and be preferably diode DB3 (rather than resistance RB16).

Specifically, as shown in figure 9, in the voltage detecting circuit 104, the anode and diode of the diode DB3 The anode connection of DB2；The negative electrode of the diode DB3 is used as voltage acquisition output terminals A DC, now, voltage detecting output End ADC output voltage be：V_ADC=V_A-V_DB3.By the output voltage V of voltage detecting output terminals A DC_ADCTransmit to external control Equipment carries out Treatment Analysis, to control the working condition of front end power circuit 101 according to analysis result, so as to control the first power supply The output voltage of the power supply outfan OUT2 of outfan OUT1 and second.

In the present embodiment, the present embodiment provide low-power consumption voltage stabilizing backlight control circuit main operational principle with The basic functional principle of Fig. 8 illustrated embodiments is identical, mainly includes：When backlight of television power supply is opened, switching tube QB1 leads Logical to enter working condition, the access of high level VCC causes diode DB2DB2 to turn on, and circuit passes through resistance RB18, diode DB2 It is operated with switching tube QB1 loops, the voltage V of the junction point of diode DB2 and resistance RB18_A=V_DB2+V_QB1；Meanwhile, two Pole pipe DB3 is turned on, by voltage V_ATransmit to voltage detecting output terminals A DC, now, the output voltage of voltage detecting output terminals A DC For：V_ADC=V_A-V_DB3.In closing television machine backlight electric power, switching tube QB1 enters cut-off state, and LED string two ends keep permanent Pressure thus there is the high level much larger than 3.3V at LED- ends, therefore diode DB1 reversely ends, LED string and voltage detecting Open circuit is equivalent between circuit 104, i.e., LED string will pass through without weak current, thus will not produce glimmer phenomenon.

The first embodiment of voltage detecting circuit 104 and second embodiment are avoided that and are closing backlight LED During lamp string source, it is to avoid the current signal that voltage acquisition output terminals A DC_12V or voltage detecting output terminals A DC are played a reversed role flows into backlight LED, so that backlight LED produces glimmer phenomenon.But, as shown in Figure 8 and Figure 9, due to the first of voltage detecting circuit 104 Plant embodiment and second embodiment introduces high level VCC, therefore, even if in the state of backlight is closed, resistance RB18 still can produce voltage V_AExport to voltage detecting output terminals A DC, thus no matter whether LED string closes, voltage detecting There is certain voltage signal in output terminals A DC, so that its external control devices (such as analog-digital converter) for being connected is long Phase is in running order, thus increased the unnecessary power consumption of external control deviceses to a certain extent.Therefore, it is necessary to study Go out the other embodiment with regard to voltage detecting circuit 104.

It is the physical circuit schematic diagram of the third embodiment of the voltage detecting circuit that the present invention is provided referring to Figure 10.

In the third embodiment of voltage detecting circuit 104, itself and the first embodiment, second embodiment Filter circuit of pressure-stabilizing 1042 can be provided with, the basic composition of the filter circuit of pressure-stabilizing 1042 is identical with operation principle, and here is no longer Repeat.Present embodiment is with the distinctive points of the first embodiment, second embodiment：Voltage detecting circuit 104 leads to Cross switching tube QB3, resistance RB19 and resistance RB20 realizes output or disconnects the voltage connection of P points.

Specifically, the voltage detecting circuit 104 includes that voltage acquisition input (being connected with P points), Regulate signal are input into End Cont_S and voltage detecting output terminals A DC；An outfan is drawn with the junction of the LED string in switching tube (QB1), with The voltage acquisition input connection.

As shown in Figure 10, voltage detecting circuit 104 includes switching tube QB3, resistance RB19 and resistance RB20；Wherein, switch Pipe QB3 can be the audion of NPN type or the metal-oxide-semiconductor of N-channel.With switching tube QB3 can be as NPN type audion as a example by, open The colelctor electrode for closing pipe QB3 is connected on the switching tube QB1 and junction P of LED string, the emitter stage and resistance of switching tube QB3 One end connection of RB19, the other end of resistance RB19 is connected with the input of filter circuit of pressure-stabilizing 1042；One end of resistance RB20 It is connected with the base stage of switching tube QB3, the other end of resistance RB20 is used as Regulate signal input Cont_S.By controlling the tune The level value of section signal input part Cont_S, when the LED string is turned on, controlling switch pipe QB3 is conducting state, will be switched The magnitude of voltage V of the pipe QB1 and junction P of the LED string_ACollection output is to voltage detecting output terminals A DC；Described When LED string is turned off, controlling switch pipe QB3 is cut-off state, so as to disconnect the voltage detecting circuit 104 with the junction The electrical connection of P.

Preferably, the switch controlling signal of switching tube QB1 is synchronous with the Regulate signal of Regulate signal input Cont_S, and Preferably it is controlled using same control terminal.

Specifically, in backlight open, pipe QB1 is in the conduction state for controlling switch, while being Regulate signal input Cont_S accesses high level, then switching tube QB3 is synchronously turned on, then flow through the setting electric current of the electric current for circuit of LED string, and electricity Pressure detection output ADC magnitude of voltage be：V_ADC=V_A* RB17/ (RB19+RB17), V_ADCSignal sends PCT to.

When backlight is closed, when controlling switch pipe QB1 is turned off, and low level is set for Regulate signal input Cont_S, Then switching tube QB3 synchronously ends, and equivalent to open circuit between LED string and voltage detecting circuit 104, therefore LED string is complete Close, without glimmer phenomenon, also, because switching tube QB3 is in cut-off state, therefore voltage detecting output terminals A DC does not have in theory There is voltage signal, therefore, the PCT that it is connected carries out related place without the need for the signal to voltage detecting output terminals A DC Reason.For example, when PCT includes analog-digital converter, then will not be to voltage detecting output terminals A DC when backlight is closed Signal carry out analog digital conversion (because voltage detecting output terminals A DC no signal output).Therefore, the 3rd embodiment is provided Voltage detecting circuit has certain superiority than first, second embodiment.

It is the physical circuit schematic diagram of the 4th kind of embodiment of the voltage detecting circuit that the present invention is provided referring to Figure 11.

In the 4th kind of embodiment of voltage detecting circuit 104, the basis of its 3rd embodiment provided in Figure 10 On, further, it is additionally provided with switching tube QB4, resistance RB22 and resistance RB23.Wherein, switching tube QB4 can for audion or Metal-oxide-semiconductor.

When switching tube QB4 is audion, the emitter stage of switching tube QB4 is connected to ground；The base stage of switching tube QB4 is by electricity Resistance RB22 is connected to ground；The base stage of switching tube QB4 is also used as the Regulate signal input Cont_S by resistance RB23；Switch The colelctor electrode of pipe QB4 is connected by resistance RB20 with switching tube QB3, including：When switching tube QB3 is audion, switching tube QB4 Colelctor electrode be connected with the base stage of switching tube QB3；When switching tube QB3 is field effect transistor, colelctor electrode and the switch of switching tube QB4 The source electrode connection of pipe QB3；

When switching tube QB4 is field effect transistor, the source electrode of switching tube QB4 is connected to ground；The grid of switching tube QB4 is by electricity Resistance RB22 is connected to ground；The grid of switching tube QB4 is also used as the Regulate signal input Cont_S by resistance RB23；Switch The drain electrode of pipe QB4 is connected by resistance RB20 with switching tube QB3, including：When switching tube QB3 is audion, switching tube QB4's Drain electrode is connected with the base stage of switching tube QB3；When switching tube QB3 is field effect transistor, drain electrode and the switching tube QB3 of switching tube QB4 Source electrode connection.

Specifically, so that switching tube QB4 is as audion as an example, on the basis of the 3rd embodiment, one end of resistance RB20 It is connected with the base stage of switching tube QB3, the other end of resistance RB20 is connected with the colelctor electrode of switching tube QB4, the transmitting of switching tube QB4 Pole is grounded；The base stage of switching tube QB4 is grounded after series resistor RB22, and as Regulate signal after series resistor RB23 The base stage of input Cont_S, i.e. one end of resistance RB23 as Regulate signal input Cont_S, the other end and switching tube QB4 Connection, the Regulate signal that Regulate signal input Cont_S is accessed accesses switching tube QB4.

Preferably, the switch controlling signal of switching tube QB1 is synchronous with the Regulate signal of Regulate signal input Cont_S, and Preferably it is controlled using same control terminal.Therefore, the basic functional principle of the voltage regulator circuit 104 of present embodiment It is：

In backlight open, pipe QB1 is in the conduction state for controlling switch, while accessing for Regulate signal input Cont_S High level, then switching tube QB4 synchronously conductings then flow through the setting electric current of the electric current for circuit of LED string, switching tube QB4 conductings Afterwards resistance RB21 and resistance RB20 carries out switching tube QB3 is turned on after partial pressure, and the magnitude of voltage of voltage detecting output terminals A DC is： V_ADC=V_A* RB17/ (RB19+RB17), V_ADCSignal sends PCT to.

When backlight is closed, when controlling switch pipe QB1 is turned off, and low level is set for Regulate signal input Cont_S, Then switching tube QB4, switching tube QB3 synchronously end, equivalent to open circuit between LED string and voltage detecting circuit 104, therefore LED Lamp string is fully closed, without glimmer phenomenon, also, because switching tube QB3 is in cut-off state, therefore voltage detecting outfan ADC does not have in theory voltage signal, therefore, the PCT that it is connected is without the need for the letter to voltage detecting output terminals A DC Number carry out relevant treatment.For example, when PCT includes analog-digital converter, then voltage will not be examined when backlight is closed Surveying the signal of output terminals A DC carries out analog digital conversion (because the output of voltage detecting output terminals A DC no signal).

It is that the constant current of the low-power consumption that the present invention is provided is shown with the structure of the another embodiment of controlling circuit of voltage regulation referring to Figure 12 It is intended to.It is the structural representation of the another embodiment of the backlight control circuit of the low-power consumption that the present invention is provided referring to Figure 13.

Wherein, the constant current of the low-power consumption in Figure 12 is equal with the backlight control circuit of the low-power consumption of Figure 13 with controlling circuit of voltage regulation It is input into including front end power circuit 101, DC-DC voltage regulator circuits 102, rear end linear constant current circuit 103, and control signal End Cont, reference signal input PWM_REF, voltage acquisition output terminals A DC_12V (or voltage detecting output terminals A DC) pass through Control master chip 105 is controlled.And, front end power circuit 101, the linear Constant Electric Current of DC-DC voltage regulator circuits 102, rear end The realization of each several part circuit of road 103 is identical with described previously, will not be described here.The constant current of the low-power consumption in Figure 12 and voltage stabilizing control Circuit processed is that the backlight control circuit of low-power consumption is further wrapped with the distinctive points of the backlight control circuit of the low-power consumption of Figure 13 Voltage detecting circuit 104 has been included, and the specific embodiment of voltage detecting circuit 104 is identical with described previously with operation principle, Will not be described here.Therefore, Figure 13 provide low-power consumption backlight control circuit can also further with Regulate signal input Cont_S connects, for the annexation that control voltage detects circuit 104 and LED string.

Control master chip 105 and control signal input Cont, the reference signal input PWM_REF with And voltage acquisition output terminals A DC_12V (when there is voltage detecting circuit 104, be voltage detecting output terminals A DC) is respectively Connection, it is also possible to be connected with Regulate signal input Cont_S.

The control master chip 105 is according to voltage acquisition output terminals A DC_12V (when there is voltage detecting circuit 104 When, be voltage detecting output terminals A DC) change in voltage, adjust the output to the signal magnitude of control signal input Cont, With the first power supply outfan OUT1 of the control front end power circuit 101, the output voltage values of the second power supply outfan OUT2； And the constant current reference voltage is input into the rear end linear constant current circuit 103 by the reference signal input PWM_REF V_REF。

The control master chip 105 is additionally operable to according to the on off state of the LED string to the Regulate signal input The level value of Cont_S synchronizes adjustment, including：When LED string is opened, by the level value of the Regulate signal input High level is adjusted to, when LED string is turned off, the level value of the regulation input low level is adjusted to into；And by described Reference signal input to the rear end linear constant current circuit 103 is input into the constant current reference voltage V_REF。

Specifically, when the control master chip 105 detects voltage acquisition output terminals A DC_12V (when there is voltage It is voltage detecting output terminals A DC during detection circuit 104) it is more than in advance with the voltage difference of the reference signal input PWM_REF If threshold value when, the control master chip 105 will be exported to the voltage signal dutycycle of control signal input Cont and subtracted It is little.When being embodied as, the control master chip 105 is built-in with analog-digital converter, for access the control master chip 105 Voltage signal is converted to digital signal.The voltage signal obtained from the collection of voltage acquisition output terminals A DC_12V first passes around modulus After the conversion of transducer, corresponding digital signal is obtained, then by the process of other processing units in control master chip 105.

Because the backlight control circuit that this Figure 13 is provided is provided with voltage detecting circuit 104, can be in shut-off backlight electric power When, by controlling diode DB2 so as to the current signal for effectively separating voltage detecting circuit 104 is moved back in LED string, keep away The generation of " glimmer phenomenon " is exempted from.

Also, the present embodiment is as a result of same control master chip to control signal input Cont, the reference Signal input part PWM_REF and voltage acquisition output terminals A DC_12V (are voltage when there is voltage detecting circuit 104 Detection output ADC) three terminals (when voltage detecting circuit 104 is using the 3rd embodiment and four embodiments, also wrap Include the 4th terminal Cont_S) signal processed, therefore on the basis of previously described effective effect, further may be used With in real time according to the signal intensity of reference signal input PWM_REF and voltage acquisition output terminals A DC_12V to control letter Number input Cont sends corresponding control signal, therefore can reach the rapid change to LED string running voltage and ring The beneficial effect answered.

Further, the embodiment of the present invention additionally provides the television set that a kind of adaptation power supply is adjusted, including：TV owner Plate, backlight LED light string, and the constant current of the low-power consumption described in any one and controlling circuit of voltage regulation above, or, any of the above item The voltage stabilizing backlight control circuit of the low-power consumption after described improvement.

Wherein, when television set uses the constant current of low-power consumption with controlling circuit of voltage regulation, the constant current is controlled with voltage stabilizing Circuit is connected respectively with the TV SKD and the backlight LED light string, for according to the work of backlight LED light string electricity By incoming control signal, Automatic adjusument supplies the voltage signal of the backlight LED light string to pressure, and stably exports to the electricity Depending on the supply voltage signal of mainboard, motility of the television set to the regulation of mainboard voltage and backlight voltage is improve, both realized Adjust with the voltage automatization that LED backlight quantity is adapted, reduce the power consumption of circuit switch element, in turn ensure that television set The stability of the supply voltage of mainboard.

When television set uses the voltage stabilizing backlight control circuit of low-power consumption, the voltage stabilizing backlight control circuit with it is described TV SKD and the backlight LED light string connect respectively, for when the power supply of the television set is opened, according to the backlight The running voltage of LED string, Automatic adjusument supplies the TV SKD, the voltage signal of the backlight LED light string；Closing When closing the power supply of the television set, shut-off flows through the electric current of the backlight LED light string.Wherein, the base of voltage stabilizing backlight control circuit This composition is identical with described previously with operation principle, will not be described here.The television set is in the motility for improving voltage-regulation Meanwhile, LED power consumptions are reduced, improve the service life of LED and the overall performance of mainboard.

The above is the preferred embodiment of the present invention, it is noted that for those skilled in the art For, under the premise without departing from the principles of the invention, some improvements and modifications can also be made, these improvements and modifications are also considered as Protection scope of the present invention.