Switching power supply output overvoltage locking circuit

Abstract

The utility model discloses an output overvoltage locking circuit of a switching power supply, which relates to the technical field of electronic circuits and comprises an output voltage detection circuit module, a thyristor control circuit module, an output overvoltage protection circuit module and a thyristor holding current circuit module. During use, output voltage is detected, and when the output voltage exceeds a threshold value of the three voltage stabilizing diodes connected in series, the optocoupler is switched on; when the optocoupler is conducted, current starts from VCC and flows through the resistor and the optocoupler element respectively, so that the current is injected to a trigger pin of the thyristor, and the thyristor is saturated and conducted; at the moment, VCC is pulled down by discharging of a resistor and a thyristor loop, so that overvoltage protection is achieved.

Description

TECHNICAL FIELD

[0001] The utility model relates to electronic circuit technical field, concretely is a switch power output overvoltage lock circuit. BACKGROUND

[0002] In the embedded product design, need to be powered by battery or USB interface power supply. When the misoperation makes the power supply voltage higher than the chip working voltage, it will cause the chip to burn out, and bring serious consequences. Therefore, setting output overvoltage protection between the input end of power supply and the power supply input end of chip is indispensable in product protection design. Based on the working principle of output overvoltage protection circuit, when the input voltage exceeds the set value, the power supply is cut off, which can protect the power supply itself on one hand, and also can avoid the chip damage due to high voltage.

[0003] The main IC used in the current developed power supply does not set an overvoltage detection circuit, and does not set a control pin for overvoltage lock protection, so it is urgent to build a circuit for realizing output overvoltage protection lock. UTILITY MODEL CONTENTS

[0004] The utility model aims at providing a switch power output overvoltage lock circuit, by building an additional circuit, when the output voltage of main IC exceeds the overvoltage protection (OVP) set value, the lock function can be realized, so as to avoid the damage of electrical equipment and switch power supply due to high voltage, so as to solve the technical problems existing in the above background technology.

[0005] In order to achieve the above purpose, the utility model provides the following technical scheme:

[0006] A switch power output overvoltage lock circuit, comprising an output voltage detection circuit module for detecting output voltage, a thyristor control circuit module electrically connected with the output voltage detection circuit module, and an output overvoltage protection circuit module electrically connected with the thyristor control circuit module.

[0007] The switch power output overvoltage lock circuit further comprises a thyristor holding current circuit module electrically connected with the thyristor control circuit module, wherein the thyristor holding current circuit module is used for adjusting the current through the thyristor control circuit module.

[0008] As a further technical scheme of the utility model, the output voltage detection circuit module comprises a first voltage stabilizing diode, a second voltage stabilizing diode, a third voltage stabilizing diode and a first resistor connected in series, and is connected in series with a second resistor and a first optocoupler element connected in parallel and then grounded.

[0009] As a further technical scheme of the utility model, the thyristor control circuit module includes a second optocoupler element, wherein the second optocoupler element is an NPN optocoupler element, the collector pin of the NPN optocoupler element is connected with the power supply VCC to be overvoltage detected in series with a third resistor, and the emitter pin of the NPN optocoupler element is connected in series with a first capacitor and a fourth resistor connected in parallel;Wherein, the thyristor control circuit module further includes a first thyristor, the anode pin of the first thyristor is connected in series with the first capacitor and the fourth resistor connected in parallel, and the cathode pin of the first thyristor is connected in series with a fifth resistor and a sixth resistor connected in parallel;The emitter pin of the NPN optocoupler element is electrically connected with the gate pin of the first thyristor.

[0010] As a further technical scheme of the utility model, the output overvoltage protection circuit module includes a seventh resistor and an eighth resistor connected in parallel, and one end of the seventh resistor and the eighth resistor connected in parallel is connected with the power supply VCC.

[0011] Compared with the prior art, the utility model has the advantages that:

[0012] 1、The utility model discloses a circuit structure for realizing the overvoltage protection function of the output of the IC, and the circuit structure includes an output overvoltage protection circuit module, an output voltage detection circuit module, a thyristor control circuit module and a main IC.

[0013] 2、The utility model discloses a circuit structure for realizing the overvoltage protection function of the output of the IC, and the circuit structure includes an output overvoltage protection circuit module, an output voltage detection circuit module, a thyristor control circuit module and a main IC.

[0014] 3、The utility model discloses a circuit structure for realizing the overvoltage protection function of the output of the IC, and the circuit structure includes an output overvoltage protection circuit module, an output voltage detection circuit module, a thyristor control circuit module and a main IC. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 It is the circuit block diagram of the utility model.

[0016] Figure 2 It is the total circuit diagram of the utility model.

[0017] Figure 3 It is the circuit diagram of the output voltage detection circuit module of the utility model.

[0018] Figure 4 It is the circuit diagram of the thyristor control circuit module of the utility model.

[0019] Figure 5 It is the circuit diagram of the output overvoltage protection circuit module of the utility model.

[0020] Figure 6 is a circuit diagram of the thyristor holding current circuit module of the utility model.

[0021] In the drawing: 1-thyristor control circuit module, 2-output voltage detection circuit module, 3-output overvoltage protection circuit module, 4-thyristor holding current circuit module. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the utility model will be apparently and completely described below with reference to the drawings in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, rather than all the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the utility model.

[0023] Please refer to Figures 1-6 The utility model embodiment provides a switching power output overvoltage lock dead circuit, it includes output voltage detection circuit module 2, it is used for detecting output voltage Vo+, thyristor control circuit module 1 with output voltage detection circuit module 2 electric connection, and output overvoltage protection circuit module 3 with thyristor control circuit module 1 electric connection.

[0024] Wherein, the circuit further includes thyristor holding current circuit module 4, with the electric connection of thyristor control circuit module 1;

[0025] Wherein, the thyristor holding current circuit module 4 is used for adjusting the current through the thyristor control circuit module 1.

[0026] Figure 2 The total circuit diagram of the utility model is shown, wherein, the circuit diagram of the output voltage detection circuit module 2 of the utility model is shown in the A part of the drawing, the circuit diagram of the thyristor control circuit module 1 of the utility model is shown in the B part of the drawing, and the circuit diagram of the output overvoltage protection circuit module 3 of the utility model is shown in the C part of the drawing.

[0027] Please refer to Figure 3 In the embodiment, the output voltage detection circuit module 2 includes the first voltage stabilizing diode ZD4, the second voltage stabilizing diode ZD1, the third voltage stabilizing diode ZD2 and the first resistance R33 connected in series, and is connected in series with the circuit of the second resistance R71 and the first optocoupler element U2A connected in parallel and then grounded.

[0028] Further, the output voltage detection circuit module 2 detects the output voltage Vo+, when the detected output voltage exceeds the threshold of the series connection of the first voltage stabilizing diode ZD4, the second voltage stabilizing diode ZD1 and the third voltage stabilizing diode ZD2, the photo-coupler is turned on.

[0029] Referring to Figure 4 In the embodiment, the thyristor control circuit module 1 comprises a second photo-coupler element, wherein the second photo-coupler element is preferably an NPN photo-coupler element U2B, the collector pin 4 of the NPN photo-coupler element U2B is connected in series with the third resistor R21 and then connected with the power supply VCC to be overvoltage detected, and the emitter pin 3 of the NPN photo-coupler element U2B is connected in series with the first capacitor C10 and the fourth resistor R25 connected in parallel; wherein the thyristor control circuit module 1 further comprises a first thyristor Q7, the anode pin 3 of the first thyristor Q7 is connected in series with the first capacitor C10 and the fourth resistor R25 connected in parallel, and the cathode pin 1 of the first thyristor Q7 is connected in series with the fifth resistor R43 and the sixth resistor R20 connected in parallel; the emitter pin 3 of the NPN photo-coupler element U2B is electrically connected with the gate pin 2 of the first thyristor Q7.

[0030] By adopting the above technical solution, when the photo-coupler is turned on, the current flows from the VCC through the third resistor R21 and the NPN photo-coupler element U2B, injects current into the gate pin 2 of the first thyristor Q7, so that the first thyristor Q7 is saturated and turned on; at this time, the power supply VCC is discharged by the sixth resistor R20, the fifth resistor R43 and the first thyristor Q7 circuit to be pulled low.

[0031] At this time, as long as the potential of the power supply VCC is lower than the VCC-OFF threshold of the switching power supply, the switching power supply will stop outputting pulses, at this time the switching power supply output is locked, thereby realizing overvoltage protection.

[0032] Referring to Figure 3 In the embodiment, the output overvoltage protection circuit module 3 comprises the seventh resistor R11 and the eighth resistor R2 connected in parallel, and one end of the seventh resistor R11 and the eighth resistor R2 connected in parallel is connected with the power supply VCC.

[0033] As a further illustration of the embodiment, by adjusting the seventh resistor R11 and the eighth resistor R2, so that the current flowing through the first thyristor Q7 is not less than its minimum holding current Ihold, the output OVP lock function can be realized.

[0034] The utility model discloses a working principle is: when the switch power output voltage Vo+ rises, three voltage stabilizing diode ZD4, ZD1, ZD2 switch on, drive first photocoupler element U2A switch on, through photocoupling feedback to thyristor control circuit module 1, the current sets out from power supply VCC and flows through third resistance R21 and NPN photocoupler element U2B, injects the current to the gate pin 2 of first thyristor Q7, makes first thyristor Q7 saturation conduction, at this moment, power supply VCC is discharged by sixth resistance R20, fifth resistance R43 and first thyristor Q7 loop and is pulled down, as long as the potential of power supply VCC is lower than the VCC-OFF threshold value of switch power, switch power will stop output pulse, at this moment, switch power output lock, thereby realizes overvoltage protection. When switch power output lock, need disconnect VCC voltage, and power supply can restore normal work.

[0035] It is obvious for those skilled in the art that the utility model is not limited to the details of the above-mentioned exemplary embodiments, and the utility model can be realized in other specific forms without departing from the spirit or basic characteristics of the utility model. Therefore, no matter from which point, the embodiments should be regarded as exemplary and non-restrictive, and the scope of the utility model is defined by the appended claims rather than the above description, and therefore all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the utility model. Any reference signs in the claims should not be regarded as limiting the claims involved.

[0036] In addition, it should be understood that, although the present specification is described in terms of embodiments, not every embodiment contains only one independent technical solution, and the description of the specification is only for the sake of clarity, and those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can be combined appropriately to form other embodiments that those skilled in the art can understand.

Claims

1. A switching power supply output overvoltage lockout circuit, characterized by: The application relates to a thyristor overvoltage protection circuit and a method for controlling the same. The application relates to a thyristor overvoltage protection circuit and a method for controlling the same. The application relates to a thyristor overvoltage protection circuit and a method for controlling the same. The application relates to a thyristor overvoltage protection circuit and a method for controlling the same. The application relates to a thyristor overvoltage protection circuit and a method for controlling the same. The output voltage detection circuit module comprises a first voltage stabilizing diode, a second voltage stabilizing diode, a third voltage stabilizing diode and a first resistor which are connected in series, and is connected in series with a circuit of a second resistor and a first optocoupler element which are connected in parallel and then grounded.

2. The switching power supply output overvoltage lockout circuit according to claim 1, characterized by: The thyristor control circuit module comprises a second optocoupler element, wherein the second optocoupler element is an NPN optocoupler element, the collector pin of the NPN optocoupler element is connected in series with a third resistor and then connected with a power supply VCC to be overvoltage detected, and the emitter pin of the NPN optocoupler element is connected in series with a first capacitor and a fourth resistor which are connected in parallel; wherein the thyristor control circuit module further comprises a first thyristor, the anode pin of the first thyristor is connected in series with the first capacitor and the fourth resistor which are connected in parallel, the cathode pin of the first thyristor is connected in series with a fifth resistor and a sixth resistor which are connected in parallel, and the emitter pin of the NPN optocoupler element is electrically connected with the gate pin of the first thyristor.

3. The switching power supply output overvoltage lockout circuit according to claim 2, characterized by: The output overvoltage protection circuit module comprises a seventh resistor and an eighth resistor which are connected in parallel, and one end of the seventh resistor and the eighth resistor which are connected in parallel is connected with the power supply VCC.

4. The switching power supply output overvoltage lockout circuit of claim 1, wherein: ​

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