CN204392078U - A kind of voltage threshold testing circuit - Google Patents

本实用新型提供一种电压阈值检测电路，包括导通电压检测电路、关断电压检测电路以及信号输出电路，关断电压检测电路跨接在导通电压检测电路与信号输出电路之间，导通电压检测电路用于检测导通电压阈值，关断电压检测电路用于检测关断电压阈值，信号输出电路用于根据检测结果向后端设备输出控制信号。本实用新型提供的电压阈值检测电路，包括导通电压检测电路、关断电压检测电路，导通电压检测电路用于检测导通电压阈值，关断电压检测电路用于检测关断电压阈值，分别对应于导通与关断两个控制信号，避免输入电压Vin恰好在预设的阈值临界点波动时，产生连续的开关信号Sout。

The utility model provides a voltage threshold detection circuit, which comprises a conduction voltage detection circuit, a cut-off voltage detection circuit and a signal output circuit. The cut-off voltage detection circuit is connected between the conduction voltage detection circuit and the signal output circuit, and The voltage detection circuit is used to detect the on-voltage threshold, the off-voltage detection circuit is used to detect the off-voltage threshold, and the signal output circuit is used to output a control signal to the back-end equipment according to the detection result. The voltage threshold detection circuit provided by the utility model includes a turn-on voltage detection circuit and a turn-off voltage detection circuit. The turn-on voltage detection circuit is used to detect the turn-on voltage threshold, and the turn-off voltage detection circuit is used to detect the turn-off voltage threshold. Corresponding to the two control signals of turning on and turning off, the continuous switching signal Sout is prevented from being generated when the input voltage Vin just fluctuates at a preset threshold critical point.

一种电压阈值检测电路A voltage threshold detection circuit

技术领域technical field

本实用新型涉及一种电压阈值检测电路。The utility model relates to a voltage threshold detection circuit.

背景技术Background technique

常见的DC/DC开关电源控制芯片允许在较低的输入电压下工作。而在输出负载保持不变的情况下，输入电压的降低将导致启动电流大幅增加。在极端情况下，甚至会引起前级电源启动故障或着熔断输入端保险丝。在此种工作环境中，DC/DC开关电源模块需要在恰当的输入电压范围内实现启动。Common DC/DC switching power supply control chips allow operation at lower input voltages. While the output load remains constant, a reduction in input voltage will result in a substantial increase in startup current. In extreme cases, it may even cause the front-end power supply to fail or blow the fuse at the input terminal. In such a working environment, the DC/DC switching power supply module needs to be started within an appropriate input voltage range.

图1提供了一种现有技术的输入电压检测电路示意图。FIG. 1 provides a schematic diagram of an input voltage detection circuit in the prior art.

如图1所示，电阻R1和R3组成电阻网络，实现对输入电压Vin的阈值检测。后端的三极管Q1和电阻R2、R4，实现将阈值检测转换为高低电平输出Sout。As shown in Figure 1, resistors R1 and R3 form a resistor network to detect the threshold of the input voltage Vin. The triode Q1 and resistors R2 and R4 at the back end realize the conversion of threshold detection into high and low level output Sout.

图1所示电路虽然能完成输入电压的检测，但当输入电压Vin恰好在预设的阈值临界点波动时，电路的Sout将产生连续的开关信号，严重影响后续的DC/DC开关电源的正常工作。Although the circuit shown in Figure 1 can complete the detection of the input voltage, when the input voltage Vin happens to fluctuate at the preset threshold critical point, the Sout of the circuit will generate continuous switching signals, which seriously affects the normal operation of the subsequent DC/DC switching power supply. Work.

发明内容Contents of the invention

针对现有技术中存在的缺陷，本实用新型的目的是提供一种电压阈值检测电路，该电压阈值检测电路，有两个电压阈值分别对应于导通与关断两个控制信号，避免输入电压Vin恰好在预设的阈值临界点波动时，产生连续的开关信号Sout。Aiming at the defects existing in the prior art, the purpose of this utility model is to provide a voltage threshold detection circuit, the voltage threshold detection circuit has two voltage thresholds corresponding to the two control signals of on and off respectively, so as to avoid the input voltage When Vin happens to fluctuate at a preset threshold critical point, a continuous switching signal Sout is generated.

本实用新型提供一种电压阈值检测电路，包括导通电压检测电路、关断电压检测电路以及信号输出电路，关断电压检测电路跨接在导通电压检测电路与信号输出电路之间，导通电压检测电路用于检测导通电压阈值，关断电压检测电路用于检测关断电压阈值，信号输出电路用于根据检测结果向后端设备输出控制信号。The utility model provides a voltage threshold detection circuit, which comprises a conduction voltage detection circuit, a cut-off voltage detection circuit and a signal output circuit. The cut-off voltage detection circuit is connected between the conduction voltage detection circuit and the signal output circuit, and The voltage detection circuit is used to detect the on-voltage threshold, the off-voltage detection circuit is used to detect the off-voltage threshold, and the signal output circuit is used to output a control signal to the back-end equipment according to the detection result.

进一步地，导通电压检测电路包括串联的电阻R1、稳压管DW1与电阻R2。Further, the conduction voltage detection circuit includes a resistor R1, a voltage regulator DW1 and a resistor R2 connected in series.

进一步地，信号输出电路包括电阻R4与三极管Q2，电阻R4的第一端与输入电压的正极连接，电阻R4的第二端与三极管Q2的集电极连接，三极管Q2的集电极为检测结果输出端Sout。Further, the signal output circuit includes a resistor R4 and a transistor Q2, the first end of the resistor R4 is connected to the positive pole of the input voltage, the second end of the resistor R4 is connected to the collector of the transistor Q2, and the collector of the transistor Q2 is the detection result output terminal Sout.

本实施例提供的电压阈值检测电路中，信号输出电路中的电阻4为上拉电阻，上拉电阻可以连接到输入电压上。In the voltage threshold detection circuit provided in this embodiment, the resistor 4 in the signal output circuit is a pull-up resistor, and the pull-up resistor can be connected to the input voltage.

进一步地，信号输出电路包括电阻R4与三极管Q2，电阻R4的第一端与输出电压的正极连接，电阻R4的第二端与三极管Q2的集电极连接，三极管Q2的集电极为检测结果输出端Sout。Further, the signal output circuit includes a resistor R4 and a transistor Q2, the first end of the resistor R4 is connected to the positive pole of the output voltage, the second end of the resistor R4 is connected to the collector of the transistor Q2, and the collector of the transistor Q2 is the detection result output terminal Sout.

本实施例提供的电压阈值检测电路中，信号输出电路中的电阻4，也可以根据后端DC/DC开关电源或其它设备的需求，连接到合适的电压源上。In the voltage threshold detection circuit provided in this embodiment, the resistor 4 in the signal output circuit can also be connected to a suitable voltage source according to the requirements of the back-end DC/DC switching power supply or other equipment.

进一步地，三极管Q2的基极，与稳压管DW1和电阻R2的连接端连接。Further, the base of the triode Q2 is connected to the connection terminal of the regulator DW1 and the resistor R2.

进一步地，关断电压检测电路包括串联的三极管Q1、稳压管DW2以及电阻R3。Further, the shutdown voltage detection circuit includes a transistor Q1, a voltage regulator DW2 and a resistor R3 connected in series.

进一步地，电阻R3与检测结果输出端Sout连接。Further, the resistor R3 is connected to the detection result output terminal Sout.

进一步地，关断电压阈值低于导通电压阈值。Further, the turn-off voltage threshold is lower than the turn-on voltage threshold.

进一步地，关断电压阈值与导通电压阈值的差值大于或等于0.5V。Further, the difference between the turn-off voltage threshold and the turn-on voltage threshold is greater than or equal to 0.5V.

与现有技术相比，本实用新型提供的电压阈值检测电路具有以下有益效果：Compared with the prior art, the voltage threshold detection circuit provided by the utility model has the following beneficial effects:

包括导通电压检测电路、关断电压检测电路，导通电压检测电路用于检测导通电压阈值，关断电压检测电路用于检测关断电压阈值，分别对应于导通与关断两个控制信号，避免输入电压Vin恰好在预设的阈值临界点波动时，产生连续的开关信号Sout。It includes a turn-on voltage detection circuit and a turn-off voltage detection circuit. The turn-on voltage detection circuit is used to detect the turn-on voltage threshold, and the turn-off voltage detection circuit is used to detect the turn-off voltage threshold. signal, to prevent the continuous switching signal Sout from being generated when the input voltage Vin just fluctuates at the preset threshold critical point.

附图说明Description of drawings

图1是现有技术中电压阈值检测电路图；Fig. 1 is a voltage threshold detection circuit diagram in the prior art;

图2是本实用新型的一个实施例的电压阈值检测电路的原理图。FIG. 2 is a schematic diagram of a voltage threshold detection circuit according to an embodiment of the present invention.

具体实施方式Detailed ways

下面结合附图对本实用新型的具体实施方式作更详细的描述。Below in conjunction with accompanying drawing, specific embodiment of the present utility model is described in more detail.

如图2所示，本实用新型的一个实施例的电压阈值检测电路，包括导通电压检测电路、关断电压检测电路以及信号输出电路，关断电压检测电路跨接在导通电压检测电路与信号输出电路之间。As shown in Figure 2, the voltage threshold detection circuit of an embodiment of the present invention includes a turn-on voltage detection circuit, a turn-off voltage detection circuit and a signal output circuit, and the turn-off voltage detection circuit is connected between the turn-on voltage detection circuit and the turn-on voltage detection circuit. between signal output circuits.

导通电压检测电路用于检测导通电压阈值，包括串联的电阻R1、稳压管DW1与电阻R2，导通电压检测电路直接并联于电源输入端，通过选用对应参数的稳压管DW1，获得需要的导通电压阈值V1：The conduction voltage detection circuit is used to detect the conduction voltage threshold, including the series resistance R1, the voltage regulator DW1 and the resistor R2. The conduction voltage detection circuit is directly connected in parallel to the input terminal of the power supply. By selecting the corresponding parameter of the voltage regulator DW1, the obtained Required turn-on voltage threshold V1:

V1＝Vth*(R1+R2)/R1+Vz1V1＝Vth*(R1+R2)/R1+Vz1

其中Vth为稳压管DW1的PN结的压降，Vth＝0.7V；Vz 1为稳压管DW1的击穿电压，R1为电阻R1的阻值，R2为电阻R2的阻值。Where Vth is the voltage drop of the PN junction of the voltage regulator DW1, Vth=0.7V; Vz 1 is the breakdown voltage of the voltage regulator DW1, R1 is the resistance of the resistor R1, and R2 is the resistance of the resistor R2.

由于稳压管DW1需要合适的电流才能正常工作，因此在该部分电路中选用电阻值R1和R2时，应保证回路电流能在1mA以上。Since the voltage regulator DW1 needs an appropriate current to work normally, when selecting the resistance values R1 and R2 in this part of the circuit, it should be ensured that the loop current can be above 1mA.

本实施例中，各器件参数如下：In this embodiment, each device parameter is as follows:

R1＝20K欧姆，R2＝R3＝10K欧姆，DW1＝14V，DW2＝8.2V；Q1选用SST3906，Q2选用SST3904。R1＝20K ohm, R2＝R3＝10K ohm, DW1＝14V, DW2＝8.2V; Q1 selects SST3906, Q2 selects SST3904.

信号输出电路用于根据检测结果向后端设备输出控制信号，信号输出电路包括电阻R4与三极管Q2，电阻R4的第一端与输入电压的正极Vin+连接，电阻R4的第二端与三极管Q2的集电极连接，三极管Q2的集电极为检测结果输出端Sout。The signal output circuit is used to output control signals to the back-end equipment according to the detection results. The signal output circuit includes a resistor R4 and a transistor Q2. The first end of the resistor R4 is connected to the positive pole Vin+ of the input voltage, and the second end of the resistor R4 is connected to the transistor Q2. The collector is connected, and the collector of the transistor Q2 is the detection result output terminal Sout.

本实施例提供的电压阈值检测电路中，信号输出电路中的电阻4为上拉电阻，上拉电阻可以连接到输入电压的正极Vin+上。In the voltage threshold detection circuit provided in this embodiment, the resistor 4 in the signal output circuit is a pull-up resistor, and the pull-up resistor can be connected to the positive pole Vin+ of the input voltage.

在另一个实施例中，信号输出电路包括电阻R4与三极管Q2，电阻R4的第一端与输出电压的正极连接，电阻R4的第二端与三极管Q2的集电极连接，三极管Q2的集电极为检测结果输出端Sout。In another embodiment, the signal output circuit includes a resistor R4 and a transistor Q2, the first end of the resistor R4 is connected to the positive pole of the output voltage, the second end of the resistor R4 is connected to the collector of the transistor Q2, and the collector of the transistor Q2 is The detection result output terminal Sout.

本实施例提供的电压阈值检测电路中，信号输出电路中的电阻4，也可以根据后端DC/DC开关电源或其它设备的需求，连接到合适的电压源上。In the voltage threshold detection circuit provided in this embodiment, the resistor 4 in the signal output circuit can also be connected to a suitable voltage source according to the requirements of the back-end DC/DC switching power supply or other equipment.

三极管Q2的基极，与稳压管DW1和电阻R2的连接端连接，也就是将导通电压检测电路连接到信号输出电路，将导通电压检测结果转换成合适的电平信号输出。The base of the transistor Q2 is connected to the connection end of the regulator tube DW1 and the resistor R2, that is, the conduction voltage detection circuit is connected to the signal output circuit, and the conduction voltage detection result is converted into an appropriate level signal for output.

信号输出电路具体参数如下：The specific parameters of the signal output circuit are as follows:

R4＝10K欧姆，Q2选用SST3904。R4 = 10K ohms, Q2 selects SST3904.

关断电压检测电路用于检测关断电压阈值，包括串联的三极管Q1、稳压管DW2以及电阻R3。The cut-off voltage detection circuit is used to detect the cut-off voltage threshold, and includes a series connection of a triode Q1, a voltage regulator DW2 and a resistor R3.

电阻R3与检测结果输出端Sout连接，也就是将关断电压检测电路连接到信号输出电路，将关断电压检测结果转换成合适的电平信号输出。The resistor R3 is connected to the detection result output terminal Sout, that is, the shutdown voltage detection circuit is connected to the signal output circuit, and the shutdown voltage detection result is converted into an appropriate level signal for output.

关断电压阈值V2的计算方法如下：The calculation method of the shutdown voltage threshold V2 is as follows:

V2＝Vin-Vz2-VceV2=Vin-Vz2-Vce

其中Vin为输入电压，Vz2为稳压管DW2的的击穿电压，Vce为稳压管DW2的集电极与发射极之间的电压Vce＝0.3V。Where Vin is the input voltage, Vz2 is the breakdown voltage of the voltage regulator DW2, and Vce is the voltage Vce=0.3V between the collector and the emitter of the voltage regulator DW2.

关断电压检测电路参数如下：The parameters of the shutdown voltage detection circuit are as follows:

R3＝10K欧姆，DW2＝8.2V，Q1选用SST3906。R3 = 10K ohms, DW2 = 8.2V, Q1 selects SST3906.

关断电压阈值低于导通电压阈值。The turn-off voltage threshold is lower than the turn-on voltage threshold.

在实际应用中，关断电压阈值与导通电压阈值的差值最小可以是0.5V以上，本实施例中关断电压阈值与导通电压阈值的差值为6V。In practical applications, the minimum difference between the turn-off voltage threshold and the turn-on voltage threshold may be more than 0.5V. In this embodiment, the difference between the turn-off voltage threshold and the turn-on voltage threshold is 6V.

本实施例提供的电压阈值检测电路工作过程如下：The working process of the voltage threshold detection circuit provided in this embodiment is as follows:

当输入电压Vin下降到关断电压阈值V2时，Q1将工作于关断状态，DW1两端压降由0.3V左右阶跃到14V；该信号直接作用于(正反馈)导通电压检测电路上，使得Q2的基极电流直接减小到截止电流以下，Q2快速截止；最终Q2输出由低电平信号跳变为高电平。When the input voltage Vin drops to the cut-off voltage threshold V2, Q1 will work in the cut-off state, and the voltage drop across DW1 will step from about 0.3V to 14V; this signal directly acts on the (positive feedback) turn-on voltage detection circuit , so that the base current of Q2 is directly reduced to below the cut-off current, and Q2 is cut off quickly; finally, the output of Q2 jumps from a low-level signal to a high level.

当输入电压Vin上升到导通电压阈值V1时，导通电压检测输出信号将使得三极管Q2处于饱和导通工作状态，Q2的输出由关断时的高电平跳变为导通后的低电平；同时Q2的低电平信号经R3、DW2回路作用于(正反馈)Q1及导通电压检测电路，迅速增大Q2的基极电流，使得Q2输出维持稳定低电平，为后端DC/DC开关电源或其它设备给出可靠地控制信号。When the input voltage Vin rises to the conduction voltage threshold V1, the conduction voltage detection output signal will make the transistor Q2 in a saturated conduction state, and the output of Q2 jumps from a high level when it is turned off to a low level after it is turned on. At the same time, the low-level signal of Q2 acts on (positive feedback) Q1 and the conduction voltage detection circuit through the R3 and DW2 loops, rapidly increasing the base current of Q2, so that the output of Q2 maintains a stable low level, which is the back-end DC /DC switching power supply or other equipment gives a reliable control signal.

实际工况中，DC/DC开关电源或其它设备的工作将导致Vin输入电压产生波动，只要导通电压V1和关断电压V2间的压差设计合理，就可以避免输出控制信号在临界点的波动。In actual working conditions, the operation of DC/DC switching power supply or other equipment will cause the input voltage of Vin to fluctuate. As long as the voltage difference between the on-voltage V1 and the off-voltage V2 is designed reasonably, the output control signal can be avoided at the critical point. fluctuation.

当输入电压Vin上升到导通电压阈值V1时，输出导通信号；When the input voltage Vin rises to the conduction voltage threshold V1, the conduction signal is output;

当输入电压Vin下降到小于导通电压阈值V1，但大于关断电压阈值V2时，仍输出导通信号；When the input voltage Vin drops below the on-voltage threshold V1 but greater than the off-voltage threshold V2, the on-signal is still output;

当输入电压Vin下降到关断电压阈值V2时，输出关断信号；When the input voltage Vin drops to the shutdown voltage threshold V2, the shutdown signal is output;

当输入电压Vin上升到大于关断电压阈值V2，但小于导通电压阈值V1时，仍输出关断信号。When the input voltage Vin rises to be greater than the off-voltage threshold V2 but lower than the on-voltage threshold V1, the off signal is still output.

以上详细描述了本实用新型的较佳具体实施例。应当理解，本领域的普通技术无需创造性劳动就可以根据本实用新型的构思做出诸多修改和变化。因此，凡本技术领域中技术人员依本实用新型的构思在现有技术的基础上通过逻辑分析、推理或者有限以得到的技术方案，皆应在由权利要求书所确定的保护范围内。The preferred specific embodiments of the present utility model have been described in detail above. It should be understood that those skilled in the art can make many modifications and changes according to the concept of the utility model without creative work. Therefore, all technical solutions obtained by those skilled in the art through logical analysis, reasoning or limitation based on the concept of the utility model on the basis of the prior art shall be within the protection scope determined by the claims.