A power supply output voltage down-regulation control circuit

Abstract

The present invention discloses a power supply output voltage down-regulation control circuit, comprising: a voltage sampling module, for real-time sampling of the output voltage of the power supply under test by differential sampling; a discharge control module, connected to the power supply under test, the discharge control module having a power MOS tube; a voltage down-regulation detection module, comprising a first resistor, a second resistor and a first comparator, one end of the first resistor is used to input the output voltage, the other end is connected to the in-phase input end of the first comparator, one end of the second resistor is used to input a preset voltage setting value, the other end is connected to the inverting input end of the first comparator, the output end of the first comparator is connected to the discharge control module, the first comparator is used to compare the voltage setting value and the output voltage and output a control signal, the control signal is used to control the on-off state of the power MOS tube. The present invention can achieve fast and timely response of the actual voltage when adjusting the voltage under light load or no-load conditions, and is simple to implement and has high reliability.

Description

Technical Field

[0001] The present invention relates to the technical field of power supply related technologies, and in particular to a power supply output voltage reduction control circuit. Background Art

[0002] During the actual output use of power products, there are situations where the voltage is used at light load or no load. The output voltage of the power supply is generally established very quickly when it rises, but when the voltage is adjusted under light load or no load conditions, the actual voltage will drop more slowly. The reason is that after the output capacitor is fully charged and accumulates energy, the energy of the capacitor needs to be discharged to reduce the output voltage. The energy stored in the capacitor is generally discharged by the resistor connected at both ends of the output capacitor. Considering the power consumption of the resistor and the efficiency of the whole machine, the connected resistor is generally not too large, and the effect of this resistor will be greatly reduced in the later stage of capacitor energy discharge (the voltage drops after energy discharge, and the resistance remains unchanged, which is equivalent to the overall load reduction). This causes the actual voltage to drop more slowly when the voltage is adjusted under light load or no load conditions, and the entire adjustment time will be particularly long.

[0003] In order to solve the problem that the actual voltage drops slowly when the voltage is adjusted under light load or no-load conditions, the existing technology adopts a method of briefly opening the fixed power resistor inside the power supply to discharge the discharge circuit when the voltage setting is adjusted downward. The MCU / DSP needs to sample the actual output voltage in real time and compare it with the set voltage to see if it reaches the set value, and then perform logical processing and send instructions to control the discharge to be turned on and off; in order to achieve the purpose of rapid discharge, the resistance value of the discharge circuit is generally relatively small. If the control is not timely, the discharge resistor will be overpowered for a long time and overheat, causing the resistor to be damaged; for application scenarios where the voltage needs to be set frequently up and down, the logic and time of the MCU / DSP processing control need to increase a lot of judgments, which is easy to malfunction and cause the discharge circuit to fail to respond in time or respond with a delay, and the output voltage cannot respond quickly and timely to the actual use of the set voltage. Summary of the invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes a power supply output voltage down-regulation control circuit, which can achieve fast and timely response of the actual voltage when adjusting the voltage under light load or no-load conditions, and is simple to implement and highly reliable.

[0005] A power supply output voltage reduction control circuit according to an embodiment of the first aspect of the present invention includes:

[0006] A voltage sampling module, used for real-time sampling of the output voltage of the power supply under test through differential sampling;

[0007] A discharge control module, connected to the power supply under test, wherein the discharge control module has a power MOS tube;

[0008] The voltage reduction detection module includes a first resistor, a second resistor and a first comparator, wherein one end of the first resistor is used to input the output voltage, and the other end is connected to the non-inverting input end of the first comparator; one end of the second resistor is used to input a preset voltage setting value, and the other end is connected to the inverting input end of the first comparator; the output end of the first comparator is connected to the discharge control module; the first comparator is used to compare the voltage setting value with the output voltage and output a control signal, and the control signal is used to control the on-off state of the power MOS tube.

[0009] The power supply output voltage reduction control circuit according to the embodiment of the present invention has at least the following beneficial effects:

[0010] Compared with the traditional method of comparing the actual output voltage with the set voltage in real time by MCU / DSP to see if it reaches the set value and then performing logic processing and sending instructions to control the discharge on and off, the power output voltage down-regulation control circuit of the embodiment of the present invention directly samples the output voltage of the power supply under test in real time by differential sampling, and then compares the voltage setting value and the output voltage by the first comparator and outputs a control signal to control the on-off state of the power MOS tube, so that when the voltage setting value is increased, the first comparator outputs a low level, the power MOS tube is not turned on, and no discharge is performed; when the voltage setting value is decreased, the first comparator outputs a high level, the power MOS tube is turned on, and discharge is performed at this moment. There is no need to use the MCU / DSP to do additional firmware program processing, the implementation method is simple, the cost is low, the hardware detection is completed to directly control the opening and closing of the power MOS tube, and it is more reliable than the MCU / DSP judgment and processing when the voltage is frequently adjusted up and down, and the actual voltage can be quickly and timely responded when adjusting the voltage under light load or no-load conditions, and the implementation is simple and the reliability is high.

[0011] According to some embodiments of the present invention, the voltage reduction detection module further includes a pull-down resistor, one end of which is respectively connected to the other end of the first resistor and the non-inverting input end of the first comparator, and the other end is used to connect to a power supply.

[0012] According to some embodiments of the present invention, the power supply under test has a positive voltage output terminal and a negative voltage output terminal, and the voltage sampling module includes:

[0013] A third resistor, one end of which is connected to the positive voltage output terminal;

[0014] a fourth resistor, one end of which is connected to the negative voltage output terminal;

[0015] a voltage sampling operational amplifier, wherein a non-inverting input terminal is connected to the other end of the third resistor, an inverting input terminal is connected to the other end of the fourth resistor, and an output terminal is connected to one end of the first resistor;

[0016] a fifth resistor, one end of which is respectively connected to the other end of the third resistor and the non-inverting input end of the voltage sampling operational amplifier, and the other end of which is used to connect to a ground wire;

[0017] A feedback resistor, one end of which is respectively connected to the other end of the fourth resistor and the inverting input end of the voltage sampling operational amplifier, and the other end of which is respectively connected to the output end of the voltage sampling operational amplifier and one end of the first resistor.

[0018] According to some embodiments of the present invention, the power supply under test has a positive voltage output terminal and a negative voltage output terminal, and the discharge control module includes:

[0019] The power MOS tube has a gate connected to the output end of the first comparator and a drain connected to the positive voltage output end;

[0020] A discharge power resistor, one end of which is connected to the source of the power MOS tube, and the other end of which is respectively connected to the negative voltage output terminal and the ground line;

[0021] A sixth resistor, one end of which is respectively connected to the gate of the power MOS tube and the output end of the first comparator, and the other end of which is respectively connected to the source of the power MOS tube and one end of the discharge power resistor.

[0022] According to some embodiments of the present invention, the discharge control module includes a driving chip, the input end of the driving chip is connected to the output end of the first comparator, the output end is respectively connected to the gate of the power MOS tube and one end of the sixth resistor, and the driving chip is used to enhance the control signal.

[0023] According to some embodiments of the present invention, the power supply output voltage reduction control circuit further includes multiple discharge control branches, each of which has a circuit structure identical to that of the discharge control module, and multiple discharge control branches are connected in parallel to the discharge control module.

[0024] According to some embodiments of the present invention, the power supply output voltage reduction control circuit further includes:

[0025] A working loop module, connected to the power supply under test, the working loop module comprising a voltage loop and a current loop;

[0026] An operating mode detection module, whose input end is connected to the operating loop module, and whose output end is respectively connected to the output end of the first comparator and the input end of the discharge control module. The operating mode detection module is used to detect the output state of the power supply under test, so as to output a high level when the voltage loop is working, and output a low level when the current loop is working.

[0027] According to some embodiments of the present invention, the voltage loop comprises:

[0028] A first voltage loop resistor, one end of which is used to input a preset voltage loop reference voltage;

[0029] A second voltage loop resistor, one end of which is connected to the power supply under test;

[0030] A voltage loop operational amplifier, wherein a non-inverting input terminal is connected to the other end of the first voltage loop resistor, and an inverting input terminal is connected to the other end of the second voltage loop resistor;

[0031] a voltage ring diode, a cathode of which is connected to the output terminal of the voltage ring operational amplifier;

[0032] A seventh resistor has one end connected to the anode of the voltage ring diode and the other end connected to the power supply.

[0033] According to some embodiments of the present invention, the current loop comprises:

[0034] A first current loop resistor, one end of which is used to input a preset current loop reference voltage;

[0035] A second current loop resistor, one end of which is connected to the power supply under test;

[0036] A current loop operational amplifier, wherein a non-inverting input terminal is connected to the other end of the first current loop resistor, and an inverting input terminal is connected to the other end of the second current loop resistor;

[0037] A current loop diode, a cathode of which is connected to the output end of the current loop operational amplifier, and an anode of which is respectively connected to the anode of the voltage loop diode and one end of the seventh resistor.

[0038] According to some embodiments of the present invention, the working mode detection module includes:

[0039] A second comparator, wherein a non-inverting input terminal of the second comparator is respectively connected to the output terminal of the voltage ring operational amplifier and the cathode of the voltage ring diode, and an inverting input terminal of the second comparator is respectively connected to the anode of the voltage ring diode and one end of the seventh resistor;

[0040] a triode, the base of which is connected to the output terminal of the second comparator, and the transmitter of which is connected to the ground line;

[0041] An eighth resistor, one end of which is connected to the collector of the transistor, and the other end of which is respectively connected to the output end of the first comparator and the input end of the discharge control module.

[0042] Other features and advantages of the present invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0044] Figure 1 1 is an electrical schematic diagram of a power supply output voltage reduction control circuit according to an embodiment of the present invention.

[0045] Reference numerals:

[0046] Voltage sampling module 100;

[0047] Discharge control module 200, driving chip 201;

[0048] Down-regulating voltage detection module 300;

[0049] Working loop module 400;

[0050] Working mode detection module 500. DETAILED DESCRIPTION

[0051] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0052] In the description of the present invention, if there is a description of first, second, etc., it is only for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0053] In the description of the present invention, it should be understood that descriptions involving orientation, such as orientation or positional relationship indicated as up, down, etc., are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0054] In the description of the present invention, it should be noted that, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention in combination with the specific content of the technical solution.

[0055] The following will be combined Figure 1 A clear and complete description is given of the power supply output voltage reduction control circuit according to the embodiment of the present invention. Obviously, the embodiment described below is only a part of the embodiments of the present invention, but not all of the embodiments.

[0056] refer to Figure 1 , Figure 1 1 is an electrical schematic diagram of a power supply output voltage reduction control circuit according to an embodiment of the present invention.

[0057] The power supply output voltage reduction control circuit according to the first aspect of the present invention includes a voltage sampling module 100 , a discharge control module 200 and a voltage reduction detection module 300 .

[0058] The voltage sampling module 100 is used to sample the output voltage of the power supply under test in real time through differential sampling;

[0059] The discharge control module 200 is connected to the power supply under test, and the discharge control module 200 has a power MOS tube Q1;

[0060] The voltage reduction detection module 300 includes a first resistor R1, a second resistor R2 and a first comparator U1A. One end of the first resistor R1 is used to input the output voltage, and the other end is connected to the non-inverting input end of the first comparator U1A. One end of the second resistor R2 is used to input a preset voltage setting value, and the other end is connected to the inverting input end of the first comparator U1A. The output end of the first comparator U1A is connected to the discharge control module 200. The first comparator U1A is used to compare the voltage setting value and the output voltage and output a control signal. The control signal is used to control the on-off state of the power MOS tube Q1.

[0061] In some embodiments of the present invention, the power supply under test has a positive voltage output terminal VOUT+ and a negative voltage output terminal VOUT-, and the voltage sampling module 100 includes a third resistor R7, a fourth resistor R8, a voltage sampling operational amplifier U3A, a fifth resistor R9 and a feedback resistor R11.

[0062] A third resistor R7, one end of which is connected to the positive voltage output terminal VOUT+;

[0063] a fourth resistor R8, one end of which is connected to the negative voltage output terminal VOUT-;

[0064] A voltage sampling operational amplifier U3A, whose in-phase input terminal is connected to the other end of the third resistor R7, whose inverting input terminal is connected to the other end of the fourth resistor R8, and whose output terminal is connected to one end of the first resistor R1;

[0065] A fifth resistor R9, one end of which is respectively connected to the other end of the third resistor R7 and the non-inverting input end of the voltage sampling operational amplifier U3A, and the other end of which is used to connect to the ground line;

[0066] The feedback resistor R11 has one end connected to the other end of the fourth resistor R8 and the inverting input end of the voltage sampling operational amplifier U3A, and the other end connected to the output end of the voltage sampling operational amplifier U3A and one end of the first resistor R1.

[0067] The embodiment of the present invention directly samples the output voltage of the power supply under test in real time in the form of differential sampling through the voltage sampling operational amplifier U3A. Compared with the traditional real-time sampling of the actual output voltage through MCU / DSP, the direct hardware sampling implementation is simpler, low-cost, fast in response speed, and high in reliability.

[0068] In some embodiments of the present invention, reference Figure 1 The power supply under test has a positive voltage output terminal VOUT+ and a negative voltage output terminal VOUT-, and the discharge control module 200 includes a power MOS tube Q1, a discharge power resistor Rs and a sixth resistor R14.

[0069] A power MOS tube Q1, whose gate is connected to the output terminal of the first comparator U1A, and whose drain is connected to the positive voltage output terminal VOUT+;

[0070] A discharge power resistor Rs, one end of which is connected to the source of the power MOS tube Q1, and the other end of which is connected to the negative voltage output terminal VOUT- and the ground wire respectively;

[0071] The sixth resistor R14 has one end connected to the gate of the power MOS transistor Q1 and the output end of the first comparator U1A respectively, and the other end connected to the source of the power MOS transistor Q1 and one end of the discharge power resistor Rs respectively.

[0072] It can be understood that the discharge control module 200 mainly controls the on-off of the power MOS tube Q1 to discharge through the discharge power resistor Rs.

[0073] Placing the discharge power resistor Rs between the source of the power MOS tube Q1 and the negative voltage output terminal VOUT- can achieve the effect of constant current discharge, avoiding the insignificant discharge effect when the output voltage is small. Compared with direct pure resistance discharge, constant current discharge can ensure rapid discharge in any voltage range of the downward voltage.

[0074] The voltage down detection module 300 compares the voltage setting value and the output voltage to control the power MOS tube Q1 of the discharge control module 200 to turn on, thereby achieving a rapid discharge effect. In normal operation, when the voltage setting value is increased, the Vset value (voltage setting value) will be greater than the Vmon value (output voltage), the first comparator U1A outputs a low level, the power MOS tube Q1 will not be turned on, and the discharge control module 200 will not work. When the voltage setting value is decreased, the Vset value will be less than the Vmon value, the first comparator U1A outputs a high level, the power MOS tube Q1 is turned on, and the discharge control module 200 works.

[0075] According to the power supply output voltage reduction control circuit of the embodiment of the present invention, compared with the traditional method of sampling the actual output voltage in real time through MCU / DSP to compare with the set voltage to see whether it reaches the set value, and then performing logic processing and sending instructions to control discharge on and off, the power supply output voltage reduction control circuit of the embodiment of the present invention directly samples the output voltage of the power supply under test in real time through differential sampling, and then compares the voltage setting value and the output voltage through the first comparator U1A and outputs a control signal to control the on-off state of the power MOS tube Q1, so that when the voltage setting value is increased, the first comparator U1A outputs a low level, the power MOS tube Q1 is not turned on, and no discharge is performed; when the voltage setting value is decreased, the first comparator U1A outputs a high level, the power MOS tube Q1 is turned on, and discharge is performed at this moment. There is no need for additional firmware processing through MCU / DSP, the implementation is simple and low-cost. After the hardware detection, it directly controls the opening and closing of the power MOS tube Q1. When the voltage is frequently adjusted up and down, it is more reliable than processing after the MCU / DSP makes a judgment. It can achieve a fast and timely response to the actual voltage when adjusting the voltage under light load or no-load conditions, and it is simple to implement and has high reliability.

[0076] In some embodiments of the present invention, reference Figure 1 The voltage-down detection module 300 further includes a pull-down resistor R10, one end of which is respectively connected to the other end of the first resistor R1 and the non-inverting input end of the first comparator U1A, and the other end is used to connect to a power supply.

[0077] By biasing the pull-down resistor R10 of the Vmon node, when the actual output voltage is higher than a certain voltage setting value (depending on the size of the pull-down bias, which can be adjusted by the pull-down resistor R10 or the pull-down voltage), the first comparator U1A will flip to a low level and turn off the power MOS tube Q1 in advance to avoid the situation where the power MOS tube Q1 is not turned off in time and the voltage undershoots. The pull-down resistor R10 can also ensure that the power MOS tube Q1 is in a turned-off state during normal operation.

[0078] In some embodiments of the present invention, reference Figure 1The discharge control module 200 includes a driving chip 201, the input end of the driving chip 201 is connected to the output end of the first comparator U1A, and the output end is respectively connected to the gate of the power MOS tube Q1 and one end of the sixth resistor R14. The driving chip 201 is used to enhance the control signal.

[0079] It is understandable that adding the driver chip 201 can provide a control signal that is stronger than the output signal of the first comparator U1A, and the control of the power MOS tube Q1 will be more reliable.

[0080] In some embodiments of the present invention, reference Figure 1 The power supply output voltage reduction control circuit further includes a plurality of discharge control branches, each of which has a circuit structure identical to the discharge control module 200 , and the plurality of discharge control branches are connected in parallel with the discharge control module 200 .

[0081] The constraint formula for the discharge current is:

[0082] ;

[0083] in, represents the discharge current, Indicates the drive supply voltage, Indicates the turn-on voltage of the power MOS tube Q1, Indicates the discharge power resistance.

[0084] Under the same output voltage, the energy stored in the capacitor is constant. Adding a discharge control branch is equivalent to increasing the discharge current (when the discharge control module 200 and all discharge control branches are turned on, the total discharge current is the sum of the discharge currents of the discharge control module 200 and all discharge control branches). The speed of discharging the capacitor energy will be faster, and the voltage will drop faster. Adding a discharge control branch is to consider that when the output voltage is very high and the capacitor energy is too large, the energy of the capacitor is dissipated to more branches to avoid overheating and damage to the power MOS tube Q1 when there is only one discharge.

[0085] In other embodiments of the present invention, the discharge speed can be accelerated by reducing the resistance of the discharge power resistor Rs. When the resistance of the discharge power resistor Rs is reduced, the discharge current of the discharge control module 200 will increase, the speed of discharging the capacitor energy will increase, and the voltage will drop faster; when the resistance of the discharge power resistor Rs is increased, the discharge current of the discharge control module 200 will decrease, the speed of discharging the capacitor energy will slow down, and the voltage will drop slowly.

[0086] In some embodiments of the present invention, reference Figure 1 The power supply output voltage reduction control circuit also includes a working loop module 400 and a working mode detection module 500.

[0087] A working loop module 400 is connected to the power supply under test, and the working loop module 400 includes a voltage loop and a current loop;

[0088] The working mode detection module 500 has an input end connected to the working loop module 400, and an output end connected to the output end of the first comparator U1A and the input end of the discharge control module 200 respectively. The working mode detection module 500 is used to detect the output state of the power supply under test, so as to output a high level when the voltage loop is working and output a low level when the current loop is working.

[0089] It can be understood that the working mode detection module 500 detects the output state of the power supply under test to ensure that the discharge control module 200 only works in the voltage loop (CV) output mode and is closed in the current loop (CC) output mode to avoid malfunction of the discharge control module during the current loop output.

[0090] In some embodiments of the present invention, reference Figure 1 The voltage loop includes a first voltage loop resistor R3, a second voltage loop resistor R4, a voltage loop operational amplifier U2A, a voltage loop diode D1 and a seventh resistor R12.

[0091] A first voltage loop resistor R3, one end of which is used to input a preset voltage loop reference voltage;

[0092] A second voltage loop resistor R4, one end of which is connected to the power supply under test;

[0093] A voltage loop operational amplifier U2A, whose non-inverting input terminal is connected to the other end of the first voltage loop resistor R3, and whose inverting input terminal is connected to the other end of the second voltage loop resistor R4;

[0094] The voltage loop diode D1 has a cathode connected to the output terminal of the voltage loop operational amplifier U2A;

[0095] The seventh resistor R12 has one end connected to the anode of the voltage ring diode D1 , and the other end connected to the power supply.

[0096] In some embodiments of the present invention, reference Figure 1 The current loop includes a first current loop resistor R5, a second current loop resistor R6, a current loop operational amplifier U2B and a current loop diode D2.

[0097] A first current loop resistor R5, one end of which is used to input a preset current loop reference voltage;

[0098] A second current loop resistor R6, one end of which is connected to the power supply under test;

[0099] A current loop operational amplifier U2B, whose non-inverting input terminal is connected to the other end of the first current loop resistor R5, and whose inverting input terminal is connected to the other end of the second current loop resistor R6;

[0100] The current loop diode D2 has a cathode connected to the output end of the current loop operational amplifier U2B, and an anode connected to the anode of the voltage loop diode D1 and one end of the seventh resistor R12 respectively.

[0101] In some embodiments of the present invention, reference Figure 1 The working mode detection module 500 includes a second comparator U1B, a transistor Q2 and an eighth resistor R13.

[0102] A second comparator U1B, whose non-inverting input terminal is respectively connected to the output terminal of the voltage loop operational amplifier U2A and the cathode of the voltage loop diode D1, and whose inverting input terminal is respectively connected to the anode of the voltage loop diode D1 and one end of the seventh resistor R12;

[0103] A transistor Q2, whose base is connected to the output terminal of the second comparator U1B and whose transmitter is connected to the ground line;

[0104] The eighth resistor R13 has one end connected to the collector of the transistor Q2 , and the other end connected to the output end of the first comparator U1A and the input end of the discharge control module 200 .

[0105] It can be understood that, in the CV mode, the voltage loop diode D1 is forward-conducted, the level of the inverting input terminal of the second comparator U1B will be higher than the level of the non-inverting input terminal, and the second comparator U1B outputs a low level, which does not affect the operation of the discharge control module 200; in the CC mode, the current loop diode D2 is forward-conducted, the voltage loop diode D1 is reverse-cut off, the level of the inverting input terminal of the second comparator U1B will be lower than the level of the non-inverting input terminal, and the second comparator U1B outputs a high level, the control signal of the discharge control module 200 is pulled low, and the discharge control module 200 will not work.

[0106] The embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge scope of ordinary technicians in the relevant technical field without departing from the purpose of the present invention.

Claims

1. A power supply output voltage down control circuit, characterized in that: include: A voltage sampling module, used for real-time sampling of the output voltage of the power supply under test through differential sampling; A discharge control module, connected to the power supply under test, wherein the discharge control module has a power MOS tube; A voltage down detection module, comprising a first resistor, a second resistor and a first comparator, wherein one end of the first resistor is used to input the output voltage, and the other end is connected to the non-inverting input end of the first comparator, one end of the second resistor is used to input a preset voltage setting value, and the other end is connected to the inverting input end of the first comparator, the output end of the first comparator is connected to the discharge control module, the first comparator is used to compare the voltage setting value with the output voltage and output a control signal, and the control signal is used to control the on-off state of the power MOS tube; A working loop module, connected to the power supply under test, the working loop module comprising a voltage loop and a current loop; An operating mode detection module, whose input end is connected to the operating loop module, and whose output end is respectively connected to the output end of the first comparator and the input end of the discharge control module. The operating mode detection module is used to detect the output state of the power supply under test, so as to output a high level when the voltage loop is working, and output a low level when the current loop is working.

2. The power supply output voltage down control circuit according to claim 1, characterized in that: The voltage-down detection module further includes a pull-down resistor, one end of which is connected to the other end of the first resistor and the non-inverting input end of the first comparator respectively, and the other end of which is used to connect to a power supply.

3. The power supply output voltage down-regulation control circuit according to claim 1, characterized in that: The power supply under test has a positive voltage output terminal and a negative voltage output terminal, and the voltage sampling module includes: A third resistor, one end of which is connected to the positive voltage output terminal; a fourth resistor, one end of which is connected to the negative voltage output terminal; a voltage sampling operational amplifier, wherein a non-inverting input terminal is connected to the other end of the third resistor, an inverting input terminal is connected to the other end of the fourth resistor, and an output terminal is connected to one end of the first resistor; a fifth resistor, one end of which is respectively connected to the other end of the third resistor and the non-inverting input end of the voltage sampling operational amplifier, and the other end of which is used to connect to a ground wire; A feedback resistor, one end of which is respectively connected to the other end of the fourth resistor and the inverting input end of the voltage sampling operational amplifier, and the other end of which is respectively connected to the output end of the voltage sampling operational amplifier and one end of the first resistor.

4. The power supply output voltage down control circuit according to claim 1, characterized in that: The power supply under test has a positive voltage output terminal and a negative voltage output terminal, and the discharge control module includes: The power MOS tube has a gate connected to the output end of the first comparator and a drain connected to the positive voltage output end; A discharge power resistor, one end of which is connected to the source of the power MOS tube, and the other end of which is respectively connected to the negative voltage output terminal and the ground line; A sixth resistor, one end of which is respectively connected to the gate of the power MOS tube and the output end of the first comparator, and the other end of which is respectively connected to the source of the power MOS tube and one end of the discharge power resistor.

5. The power supply output voltage down-regulation control circuit according to claim 4, characterized in that: The discharge control module includes a driving chip, the input end of the driving chip is connected to the output end of the first comparator, the output end is respectively connected to the gate of the power MOS tube and one end of the sixth resistor, and the driving chip is used to enhance the control signal.

6. The power supply output voltage down-regulation control circuit according to claim 5, characterized in that: The power supply output voltage reduction control circuit further includes a plurality of discharge control branches, each of which has a circuit structure identical to that of the discharge control module, and the plurality of discharge control branches are connected in parallel with the discharge control module.

7. The power supply output voltage down-regulation control circuit according to claim 1, characterized in that: The voltage loop includes: A first voltage loop resistor, one end of which is used to input a preset voltage loop reference voltage; A second voltage loop resistor, one end of which is connected to the power supply under test; A voltage loop operational amplifier, wherein a non-inverting input terminal is connected to the other end of the first voltage loop resistor, and an inverting input terminal is connected to the other end of the second voltage loop resistor; A voltage ring diode, a cathode of which is connected to the output terminal of the voltage ring operational amplifier; A seventh resistor has one end connected to the anode of the voltage ring diode and the other end connected to the power supply.

8. The power supply output voltage down-regulation control circuit according to claim 7, characterized in that: The current loop includes: A first current loop resistor, one end of which is used to input a preset current loop reference voltage; A second current loop resistor, one end of which is connected to the power supply under test; A current loop operational amplifier, wherein a non-inverting input terminal is connected to the other end of the first current loop resistor, and an inverting input terminal is connected to the other end of the second current loop resistor; A current loop diode, a cathode of which is connected to the output end of the current loop operational amplifier, and an anode of which is respectively connected to the anode of the voltage loop diode and one end of the seventh resistor.

9. The power supply output voltage down-regulation control circuit according to claim 8, characterized in that: The working mode detection module comprises: A second comparator, wherein a non-inverting input terminal of the second comparator is respectively connected to the output terminal of the voltage ring operational amplifier and the cathode of the voltage ring diode, and an inverting input terminal of the second comparator is respectively connected to the anode of the voltage ring diode and one end of the seventh resistor; a triode, the base of which is connected to the output terminal of the second comparator, and the transmitter of which is connected to the ground line; An eighth resistor, one end of which is connected to the collector of the transistor, and the other end of which is respectively connected to the output end of the first comparator and the input end of the discharge control module.

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