Overvoltage undervoltage overcurrent protection circuit, switching power supply and electronic equipment

Abstract

The utility model discloses an overvoltage undervoltage overcurrent protection circuit, and current detection module includes current detection integrated circuit, and current detection integrated circuit is connected with reference power module and hardware operation module electricity, to detect and export load circuit current detection logic signal, voltage detection module includes voltage detection integrated circuit, and voltage detection integrated circuit is connected with reference power module and hardware operation module electricity, to detect and export input voltage detection logic signal, hardware operation module includes the operation circuit of discrete component composition, and includes overcurrent state locking circuit in operation circuit, and one end of overcurrent state locking circuit is connected with the output end electricity of current detection module, and hardware operation module carries out logic operation according to load circuit current detection logic signal and input voltage detection logic signal, to control the power supply of load circuit, and reference power module provides reference power supply for current detection module, voltage detection module and hardware operation module.

Description

Technical Field

[0001] This utility model relates to the field of electronic circuits, specifically to an overvoltage, undervoltage, and overcurrent protection circuit, a switching power supply, and electronic equipment. Background Technology

[0002] In actual operation, power systems and electronic equipment may encounter various emergencies, such as lightning strikes, instantaneous high voltage caused by grid fluctuations, low battery power or insufficient power supply, surge currents caused by load short circuits or motor starting, user misoperation, or external interference. Overvoltage, undervoltage, and overcurrent protection circuits can respond promptly to these abnormal situations, preventing the entire system from collapsing and improving the robustness and reliability of equipment in harsh environments. Many industries (such as industrial control, communications, automotive electronics, and medical equipment) also have strict requirements for electrical safety, and standards clearly stipulate that overvoltage, undervoltage, and overcurrent protection functions are mandatory. Overvoltage protection circuits can quickly act when the voltage rises abnormally, limiting the voltage to a safe range and preventing damage to sensitive components. Undervoltage protection circuits cut off the output when the input voltage is lower than the minimum value required for normal operation, preventing the system from operating in an unstable or abnormal state. Overcurrent protection circuits can disconnect the circuit or limit the current when abnormally large currents are detected, preventing thermal damage and fire risks.

[0003] Currently, there are two common types of hardware overvoltage, undervoltage, and overcurrent protection circuits. One type is composed of discrete components, which has the advantages of high cost-effectiveness and low cost, but the disadvantages of poor consistency and unstable performance due to discrete components. The other type is composed of integrated circuits, which has the advantages of good consistency and stable performance, but the disadvantages of high cost. Summary of the Invention

[0004] Based on the above situation, the main purpose of this utility model is to provide an overvoltage, undervoltage and overcurrent protection circuit that is stable in performance, cost-effective and low in cost.

[0005] To achieve the above objectives, the technical solution adopted by this utility model is as follows:

[0006] An overvoltage, undervoltage, and overcurrent protection circuit includes: a reference power supply module, a current detection module, a voltage detection module, and a hardware processing module.

[0007] The current detection module includes a current detection integrated circuit, which is electrically connected to the reference power supply module and the hardware computing module to detect the current of the load circuit and output a load circuit current detection logic signal.

[0008] The voltage detection module includes a voltage detection integrated circuit, which is electrically connected to the reference power supply module and the hardware computing module to detect the voltage of the input power supply and output an input voltage detection logic signal.

[0009] The hardware computing module includes a computing circuit composed of discrete components. The computing circuit includes an overcurrent state lockout circuit. One end of the overcurrent state lockout circuit is electrically connected to the output terminal of the current detection module. The hardware computing module performs logic operations based on the load circuit current detection logic signal and the input voltage detection logic signal to control the power supply of the load circuit according to the result of the logic operation.

[0010] The reference power supply module provides a reference power supply for the current detection module, the voltage detection module, and the hardware computing module.

[0011] Preferably, the reference power supply module includes a low-dropout regulator, one end of which is connected to the input power supply and the other end outputs the reference power supply.

[0012] Preferably, the reference power supply is 3.3V.

[0013] Preferably, the current detection integrated circuit includes an operational amplifier subtractor and a voltage comparator.

[0014] The operational amplifier subtractor includes a positive input terminal and an inverting input terminal. The positive input terminal is electrically connected to the input power supply, and the inverting input terminal is electrically connected to the sampling circuit between the input power supply and the load circuit.

[0015] The voltage comparator includes a positive input terminal and an inverting input terminal. The output terminal of the operational amplifier subtractor is electrically connected to the positive input terminal of the voltage comparator. The inverting input terminal of the voltage comparator is connected to the reference power supply. The output terminal of the voltage comparator is electrically connected to the overcurrent state lockout circuit.

[0016] Preferably, the voltage detection integrated circuit includes a dual-channel voltage comparator, which includes an undervoltage comparison positive input terminal and an undervoltage comparison inverting input terminal, as well as an overvoltage comparison positive input terminal and an overvoltage comparison inverting input terminal.

[0017] The undervoltage comparator's positive input terminal is connected to the input power supply, the undervoltage comparator's negative input terminal is connected to the reference power supply, the overvoltage comparator's positive input terminal is connected to the reference power supply, the overvoltage comparator's negative input terminal is connected to the input power supply, and the first and second output terminals of the dual-channel voltage comparator are both electrically connected to the hardware computing module.

[0018] Preferably, the computing circuit of the hardware computing module further includes a switching circuit and a logic operation circuit.

[0019] The first terminal of the switching circuit is electrically connected to one input terminal of the current detection module, the second terminal of the switching circuit is electrically connected to the first terminal of the logic operation circuit, the second terminal of the logic operation circuit is electrically connected to the output terminal of the voltage detection module, and the other terminal of the overcurrent state lockout circuit is electrically connected to the second terminal of the switching circuit.

[0020] Preferably, the switching circuit includes a PMOS transistor, an NPN transistor, and a diode, and the logic operation circuit includes an undervoltage detection diode and an overvoltage detection diode.

[0021] The source of the PMOS transistor is electrically connected to an input terminal of the current detection module, the drain of the PMOS transistor is electrically connected to the load circuit, the gate of the PMOS transistor is electrically connected to the collector of the NPN transistor, the emitter of the NPN transistor is grounded, and the base of the NPN transistor is electrically connected to the negative terminal of the diode.

[0022] The negative terminal of the undervoltage detection diode is electrically connected to one output terminal of the voltage detection module, the positive terminal of the undervoltage detection diode is electrically connected to the positive terminal of the diode in the switching circuit, the negative terminal of the overvoltage detection diode is electrically connected to the other output terminal of the voltage detection module, and the positive terminal of the overvoltage detection diode is electrically connected to the positive terminal of the diode in the switching circuit.

[0023] Preferably, the overcurrent state lockout circuit includes a first resistor, a second resistor, a third resistor, a fourth resistor, a first diode, a second diode, a PNP transistor, and an NPN transistor.

[0024] One end of the first resistor is connected to the reference power supply, and the other end is electrically connected to the anode of the first diode. The cathode of the first diode is electrically connected to one end of the second resistor and the collector of the PNP transistor. The other end of the second resistor is electrically connected to the base of the NPN transistor. The emitter of the NPN transistor is grounded. The collector of the NPN transistor is electrically connected to the cathode of the second diode and one end of the third resistor. The other end of the third resistor is electrically connected to the base of the PNP transistor. The emitter of the PNP transistor is connected to the reference power supply. The anode of the second diode is electrically connected to one end of the fourth resistor, and the other end of the fourth resistor is connected to the reference power supply.

[0025] The present invention also discloses a switching power supply, wherein the switching power supply includes the overvoltage, undervoltage and overcurrent protection circuit described in any one of the present invention, so as to realize the control of the power supply circuit.

[0026] The present invention also discloses an electronic device, which includes the switching power supply described in the present invention.

[0027] This invention combines the advantages of integrated circuits and discrete component overvoltage, undervoltage, and overcurrent protection circuits. Integrated circuit chips are used in the analog circuit section to ensure circuit stability, while discrete components are used in the digital processing circuit to improve cost-effectiveness. By combining the stability of integrated chip protection circuits with the low cost of discrete component protection circuits, a stable, efficient, and low-cost overvoltage, undervoltage, and overcurrent protection circuit is obtained.

[0028] Other beneficial effects of this utility model will be explained in the specific embodiments through the introduction of specific technical features and technical solutions. Those skilled in the art should be able to understand the beneficial technical effects brought about by these technical features and technical solutions through the introduction of these technical features and technical solutions. Attached Figure Description

[0029] The preferred embodiment of the overvoltage, undervoltage, and overcurrent protection circuit according to the present invention will be described below with reference to the accompanying drawings. In the drawings:

[0030] Figure 1 This is a block diagram of an overvoltage, undervoltage, and overcurrent protection circuit according to a preferred embodiment of the present invention.

[0031] Figure 2 This is a circuit schematic diagram of a reference power supply module according to a preferred embodiment of the present invention;

[0032] Figure 3 This is a circuit block diagram of a current detection module according to a preferred embodiment of the present invention;

[0033] Figure 4 and 5 This is a circuit diagram of a current detection module according to a preferred embodiment of the present invention;

[0034] Figure 6 This is a circuit diagram of a voltage detection module according to a preferred embodiment of the present invention;

[0035] Figure 7 This is a circuit block diagram of a hardware computing module according to a preferred embodiment of the present invention;

[0036] Figure 8 This is a circuit diagram of a hardware computing module according to a preferred embodiment of the present invention. Detailed Implementation

[0037] The technical solutions of this utility model will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this utility model, and not all of them. Based on the embodiments of this utility model, other embodiments obtained by those skilled in the art without creative effort are all within the scope of protection of this utility model.

[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items. In this application, "first," "second," "third," "fourth," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0039] Figure 1 The block diagram of an overvoltage, undervoltage, and overcurrent protection circuit according to a preferred embodiment of the present invention includes a reference power supply module 100, a current detection module 200, a voltage detection module 300, and a hardware processing module 400. The current detection module 200 includes a current detection integrated circuit; that is, the current detection module 200 is implemented using an integrated circuit chip. The current detection integrated circuit is electrically connected to the reference power supply module 100 and the hardware processing module 400 to detect the current of the load circuit and output a load circuit current detection logic signal (CURRENT_OD). The voltage detection module 300 includes a voltage detection integrated circuit; that is, the voltage detection module 300 is implemented using an integrated circuit chip. The voltage detection integrated circuit is electrically connected to the reference power supply module 100 and the hardware processing module 400 to detect the voltage of the input power supply VCC. It outputs input voltage detection logic signals (LV_OD, undervoltage detection logic signal and OV_OD, overvoltage detection logic signal); the hardware operation module 400 includes an operation circuit composed of discrete components, that is, the hardware operation module is implemented using discrete components, rather than using integrated circuit chips. The operation circuit includes an overcurrent state lockout circuit, one end of which is electrically connected to the output terminal of the current detection module 200. The hardware operation module 400 performs logic operations based on the load circuit current detection logic signal and the input voltage detection logic signal, so as to control the power supply of the load circuit according to the result of the logic operation; wherein, the reference power supply module 100 provides a reference power supply and an input power supply VCC to the current detection module 200, the voltage detection module 300 and the hardware operation module 400.

[0040] This invention combines the advantages of integrated circuits and discrete component overvoltage, undervoltage, and overcurrent protection circuits. Integrated circuit chips are used in the analog circuit section to ensure circuit stability, while discrete components are used in the digital processing circuit to improve cost-effectiveness. By combining the stability of integrated chip protection circuits with the low cost of discrete component protection circuits, a stable, efficient, and low-cost overvoltage, undervoltage, and overcurrent protection circuit is obtained.

[0041] In a preferred embodiment, the reference power supply module can be implemented using a low-dropout regulator (LDO) to provide a stable reference power signal for other circuits. A stable voltage is crucial for power supply voltage detection. One end of the LDO is connected to the input power supply, and the other end outputs the reference power supply. In specific embodiments, the reference power supply can be 3.3V, or other voltage values; this invention does not impose any limitations.

[0042] like Figure 2 The diagram shows a preferred implementation circuit for a reference power supply module. U1 is a low dropout regulator (LDO), which outputs a 3.3V reference power supply from the input power supply voltage VCC. C1 and C3 are input filter capacitors, and C2 and C4 are output filter capacitors. C1 and C2 can be 10uF, and C3 and C4 can be 0.1uF. These are just exemplary values, and appropriate capacitor values ​​can be selected according to the circuit design requirements.

[0043] In a preferred embodiment, such as Figure 3 As shown, the current detection integrated circuit in the current detection module 200 may include an operational amplifier subtractor 201 and a voltage comparator 202. The operational amplifier subtractor 201 includes a positive input terminal and an inverting input terminal. The positive input terminal is electrically connected to the input power supply VCC, and the inverting input terminal is electrically connected to the sampling circuit between the input power supply VCC and the load circuit. The voltage comparator 202 includes a positive input terminal and an inverting input terminal. The output terminal of the operational amplifier subtractor 201 is electrically connected to the positive input terminal of the voltage comparator 202, the inverting input terminal of the voltage comparator 202 is connected to the reference power supply, and the output terminal of the voltage comparator 202 is electrically connected to the overcurrent state lockout circuit in the hardware operation module 400.

[0044] like Figure 4 and 5 The diagram shows a preferred embodiment of the current detection module 200. Figure 4U3 in the diagram is an operational amplifier subtractor (LMV321). The input power ground terminal VSS of U3 is grounded, and its VDD terminal is connected to a 3.3V reference power supply. The non-inverting input terminal IN+ of U3 is connected to the input power supply VCC through resistors R7 and R12. The inverting input terminal IN- of U3 is electrically connected to VDD through resistor R6. VDD is the voltage across the sampling circuit between the input power supply VCC and the load circuit; typically, a sampling circuit formed by two resistors connected in series can be used. The output signal (I_TO_V) of U3's output terminal OUT is... Figure 5 The voltage comparator U2 (COS3201TR) has its non-inverting input IN+ electrically connected. Its inverting input is connected to the reference power supply (VCC_3.3V) via sampling resistors R10 and R11. C5 and C7 are filter capacitors, both 0.1uF. The output OUT of U2 outputs the load circuit current detection logic signal (CURRENT_OD) to the hardware arithmetic module 400. The VCC terminal of U2 is connected to the reference power supply (VCC_3.3V), and the GND terminal is grounded. Since the U2 output OUT only has low and high impedance states, a pull-up resistor R8 is needed to connect the output OUT to the reference power supply to output a high level.

[0045] The operational amplifier subtractor 201 subtracts the voltages VCC and VDD across the sampling resistor R, i.e., VCC - VDD. Since the output signal I_TO_V of the operational amplifier subtractor 201 = VCC - VDD = R * I (where I is the actual load current of the circuit), when R is known, the actual load current of the circuit can be indirectly detected simply by detecting the VCC - VDD voltage. Next, the voltage comparator compares I_TO_V with a known voltage to detect whether the current of the load circuit exceeds a preset value. When the current exceeds the preset value, the current detection module 200 outputs a logic 1 signal to the hardware arithmetic module 400; otherwise, it outputs a logic 0.

[0046] In a preferred embodiment, the voltage detection integrated circuit in the voltage detection module 300 may include a dual-channel voltage comparator. The dual-channel voltage comparator includes an undervoltage comparison positive input terminal and an undervoltage comparison inverse input terminal, as well as an overvoltage comparison positive input terminal and an overvoltage comparison inverse input terminal. The undervoltage comparison positive input terminal is connected to the input power supply VCC, the undervoltage comparison inverse input terminal is connected to the reference power supply, the overvoltage comparison positive input terminal is connected to the reference power supply, and the overvoltage comparison inverse input terminal is connected to the input power supply VCC. The first and second output terminals of the dual-channel voltage comparator are both electrically connected to the hardware computing module 400.

[0047] like Figure 6 The diagram shows a preferred embodiment of the voltage detection module 300. Figure 6The U4 (LM393) in the code is a dual-channel voltage comparator, including an undervoltage comparison positive input (IN / A+) and an undervoltage comparison inverting input (IN / A-), an overvoltage comparison positive input (IN / B+) and an overvoltage comparison inverting input (IN / B-), a first output (OUT / A), and a second output (OUT / B). The undervoltage comparison positive input (IN / A+) is connected to the input power supply VCC through resistors R13 and R18, and the undervoltage comparison inverting input (IN / A-) is connected to the reference power supply (VCC_3.3V) through resistors R14 and R17. The first output (OUT / A) outputs an undervoltage detection logic signal (LV_OD) to the hardware operation module 400. The overvoltage comparison positive input (IN / B+) is connected to the reference power supply (VCC_3.3V) through resistors R15 and R20, and the overvoltage comparison inverting input (IN / B-) is connected to the input power supply VCC through resistors R16 and R19. The second output (OUT / B) outputs an overvoltage detection logic signal (OV_OD) to the hardware operation module 400. The system will output logic 0 if the voltage is lower than the preset minimum voltage or higher than the maximum voltage; otherwise, it will output logic 1.

[0048] The reference power supply module 100, current detection module 200 and voltage detection module in the above embodiments of this utility model are all designed with very low cost integrated circuit chips, which completely avoids the disadvantages of poor consistency and unstable performance caused by discrete components in the prior art, and at the same time does not bring excessive cost, while ensuring the stable performance of the circuit.

[0049] In a preferred embodiment, such as Figure 7 As shown, the hardware arithmetic module 400 also includes a switching circuit 401 and a logic operation circuit 402. The first terminal of the switching circuit 401 is electrically connected to an input terminal of the current detection module (not shown in the figure), for example, with... Figure 4 The inverting input terminal IN- is electrically connected, the second terminal of the switching circuit 401 is electrically connected to the first terminal of the logic operation circuit 402, and the second terminal of the logic operation circuit 402 is electrically connected to the output terminal of the voltage detection module 300, for example... Figure 6 The first output terminal OUT / A and the second output terminal OUT / B of U4 are connected to the second terminal of the overcurrent state lockout circuit 403.

[0050] In specific implementation methods, such as Figure 8 As shown, the switching circuit 401 may include a PMOS transistor Q1, an NPN transistor Q2, and a diode D1. The logic operation circuit 402 may include an undervoltage detection diode D4 and an overvoltage detection diode D5. The source of the PMOS transistor Q1 is electrically connected to an input terminal of the current detection module, for example, with... Figure 4The inverting input terminal IN- is electrically connected (not shown in the figure). The drain of PMOS transistor Q1 is electrically connected to the load circuit P2. The gate of PMOS transistor Q1 is electrically connected to the collector of NPN transistor Q2. The emitter of NPN transistor Q2 is grounded. The base of NPN transistor Q2 is electrically connected to the cathode of diode D1. The cathode of undervoltage detection diode D4 is electrically connected to an output terminal of voltage detection module 300, for example, with... Figure 6 The first output terminal OUT / A is electrically connected; the positive terminal of the undervoltage detection diode is electrically connected to the positive terminal of diode D1 in the switching circuit; and the negative terminal of the overvoltage detection diode D5 is electrically connected to the other output terminal of the voltage detection module 300, for example, with... Figure 6 The second output terminal OUT / B is electrically connected, and the positive terminal of the overvoltage detection diode D5 is electrically connected to the positive terminal of the diode D1 in the switching circuit. Figure 8 P1 in the diagram is the input power supply VCC interface circuit.

[0051] like Figure 8 As shown, the overcurrent state lockout circuit 403 may include a first resistor R21, a second resistor R5, a third resistor R4, a fourth resistor R3, a first diode D3, a second diode D2, a PNP transistor Q3, and an NPN transistor Q4. One end of the first resistor R21 is connected to the reference power supply, and the other end is electrically connected to the anode of the first diode D3. The cathode of the first diode D3 is electrically connected to one end of the second resistor R5 and the collector of the PNP transistor Q3. The other end of the second resistor R5 is electrically connected to the base of the NPN transistor Q4. The emitter of the NPN transistor Q4 is grounded. The collector of the NPN transistor Q4 is electrically connected to the cathode of the second diode D2 and one end of the third resistor R4. The other end of the third resistor R4 is electrically connected to the base of the PNP transistor Q3. The emitter of the PNP transistor Q3 is connected to the reference power supply. The anode of the second diode D2 is electrically connected to one end of the fourth resistor R3, and the other end of the fourth resistor R3 is connected to the reference power supply. In the diagram, the second resistor R5 and the fourth resistor R3 can be selected with a resistance of 1MΩ, and the third resistor R4 can be selected with a resistance of 100KΩ.

[0052] Since overcurrent may be caused by a break in the load circuit, the protection circuit has an overcurrent signal latching function to protect the power supply, while overvoltage and undervoltage signals are not latched. When no overcurrent occurs, the current detection module 200 outputs logic 0, Q4 is not conducting, and therefore Q3 is also not conducting. Conversely, when an overcurrent signal occurs, the current detection module 200 outputs logic 1, Q4 conducts, causing Q3 to also conduct, forming positive feedback in the circuit. When the overcurrent signal is eliminated, Q4 continues to conduct, thus latching the overcurrent signal.

[0053] It should be noted that, Figure 8Resistors R1 and R2 in the circuit form a sampling circuit between the input power supply VCC and the load circuit P2. One end of this sampling circuit is connected to the input power supply VCC, and the other end outputs a voltage VDD to the input terminal of the current detection module 200 to perform the current detection function of the current detection module 200. Specifically, R1 can be selected as 0.05R, which is 0.05Ω, and R2 can be selected as 100K.

[0054] The hardware computing circuit in the above embodiments adopts a discrete component design, which makes the circuit more cost-effective and reduces the design cost.

[0055] When the overvoltage, undervoltage, and overcurrent protection circuit in the above embodiment is used, for example, when 1A overcurrent protection is to be achieved, the operational amplifier subtractor U3 in the current detection module 200 will subtract the voltages VCC and VDD across the sampling resistor R1. Then, when the load circuit current reaches 1A, the voltage drop across resistor R1 is 1A * 0.05R = 0.05V = 50mV (ignoring the current shunting of resistor R2). That is, when the load circuit current is below 1A, the voltage across resistor R1 is below 50mV. Simultaneously, since U3 is an electrical signal subtraction circuit, ... I_TO_V = the voltage across R1. Therefore, by comparing the I_TO_V signal with the 50mV voltage, we can determine whether there is an overcurrent. The voltage comparator U2 and resistors R10 and R11 can compare the I_TO_V signal with the 50mV voltage. By taking R11 = 4.7K and R10 = 300K, we can achieve the following: when the load current is less than 1A, I_TO_V is less than 50mV, and the voltage across the R11 voltage divider is approximately equal to 50mV. In this case, U2 will output logic 0. Conversely, when the load current is greater than 1A, U2 will output logic 1.

[0056] To implement 5V-12V voltage detection (i.e., undervoltage below 5V, overvoltage above 12V), for undervoltage detection: Let R14 = 23KΩ, R17 = 10KΩ, then the voltage across R17 is 1V, which is 1V for the IN / A- port of U4. Let R13K = 40KΩ, R18 = 10KΩ, then R18 = 1 / 5VCC. When VCC is less than 5V, the OUT / A port of U4 outputs logic 0; conversely, when VCC is greater than 5V, the OUT / A port of U4 outputs logic 1. Similarly, for overvoltage, the OUT / B port of U4 outputs logic 0; for undervoltage, the OUT / B port of U4 outputs logic 0.

[0057] The aforementioned overcurrent, overvoltage, and undervoltage detection logic signals are then processed by the hardware cloud circuit to control whether to supply power to the load circuit.

[0058] The hardware operation module includes a switching circuit, an overcurrent state lockout circuit, and a logic operation circuit. The switching circuit consists of Q1, Q2, and D1. When the positive terminal of D1 receives a high level (i.e., logic 1), it enables power supply to the subsequent circuit. The overcurrent state lockout circuit consists of R3, R4, R5, R21, Q3, Q4, D2, and D3. Its main function is to lock the overcurrent signal. When no overcurrent occurs, the output terminal CURRENT_OD of U2 outputs a low level (logo 0), Q3 and Q4 are cut off, and VCC_3V3, through R3, sends logic 1 to D1, enabling D1 to power the load circuit. When an overcurrent occurs, the output terminal CURRENT_OD of U2 outputs a high level (logo 1), which turns on Q4. After Q4 turns on, due to the presence of D2, the voltage on the left side of R3 is approximately the turn-on voltage of D2. This voltage cannot turn on the switching circuit composed of D1, Q1, and Q2. The turn-on voltage of this circuit is the turn-on voltage of D2 + 0.7V. Simultaneously, because Q4 is conducting, Q3 will also conduct. After Q3 conducts, VCC will conduct through the collector-emitter junction of Q3 and then through R5 to turn on Q4, thus establishing a positive feedback loop. This maintains the state of not supplying power to the load circuit. Without this state-keeping circuit, Q1 would continuously cycle between overcurrent-off-current decrease-on-overcurrent, which would significantly impact the lifespan of the MOSFET. D4 and D5 form a logic operation circuit. When any of LV_OD, OV_OD, or the overcurrent state lockout circuit outputs logic 0, the maximum voltage supplied to the positive terminal of D1 is the turn-on voltage of D1, preventing the switching circuit from turning on. Specifically, D1, D2, D4, and D5 are diodes of the same type.

[0059] This utility model also discloses a switching power supply, which includes the overvoltage, undervoltage and overcurrent protection circuit described in any one of the present invention, so as to realize the control of the power supply circuit.

[0060] This utility model also discloses an electronic device, which includes the switching power supply described in this invention.

[0061] Those skilled in the art will understand that, without conflict, the above-mentioned preferred solutions can be freely combined and superimposed.

[0062] It should be understood that the above-described embodiments are merely exemplary and not restrictive. Without departing from the basic principles of this utility model, any obvious or equivalent modifications or substitutions made by those skilled in the art regarding the above details will be included within the scope of the claims of this utility model.

Claims

1. An overvoltage, undervoltage, and overcurrent protection circuit, characterized in that, include: The system consists of a reference power supply module, a current detection module, a voltage detection module, and a hardware computing module. The current detection module includes a current detection integrated circuit, which is electrically connected to the reference power supply module and the hardware computing module to detect the current of the load circuit and output a load circuit current detection logic signal. The voltage detection module includes a voltage detection integrated circuit, which is electrically connected to the reference power supply module and the hardware computing module to detect the voltage of the input power supply and output an input voltage detection logic signal. The hardware computing module includes a computing circuit composed of discrete components. The computing circuit includes an overcurrent state lockout circuit. One end of the overcurrent state lockout circuit is electrically connected to the output terminal of the current detection module. The hardware computing module performs logic operations based on the load circuit current detection logic signal and the input voltage detection logic signal to control the power supply of the load circuit according to the result of the logic operation. The reference power supply module provides a reference power supply for the current detection module, the voltage detection module, and the hardware computing module.

2. The overvoltage, undervoltage, and overcurrent protection circuit according to claim 1, characterized in that, The reference power module includes a low-dropout regulator, one end of which is connected to the input power supply, and the other end outputs the reference power supply.

3. The overvoltage, undervoltage, and overcurrent protection circuit according to claim 1, characterized in that, The reference power supply is 3.3V.

4. The overvoltage, undervoltage, and overcurrent protection circuit according to claim 1, characterized in that, The current detection integrated circuit includes an operational amplifier subtractor and a voltage comparator. The operational amplifier subtractor includes a positive input terminal and an inverting input terminal. The positive input terminal is electrically connected to the input power supply, and the inverting input terminal is electrically connected to the sampling circuit between the input power supply and the load circuit. The voltage comparator includes a positive input terminal and an inverting input terminal. The output terminal of the operational amplifier subtractor is electrically connected to the positive input terminal of the voltage comparator. The inverting input terminal of the voltage comparator is connected to the reference power supply. The output terminal of the voltage comparator is electrically connected to the overcurrent state lockout circuit.

5. The overvoltage, undervoltage, and overcurrent protection circuit according to claim 1, characterized in that, The voltage detection integrated circuit includes a dual-channel voltage comparator, which includes an undervoltage comparison positive input and an undervoltage comparison inverting input, as well as an overvoltage comparison positive input and an overvoltage comparison inverting input. The undervoltage comparator's positive input terminal is connected to the input power supply, the undervoltage comparator's negative input terminal is connected to the reference power supply, the overvoltage comparator's positive input terminal is connected to the reference power supply, the overvoltage comparator's negative input terminal is connected to the input power supply, and the first and second output terminals of the dual-channel voltage comparator are both electrically connected to the hardware computing module.

6. The overvoltage, undervoltage, and overcurrent protection circuit according to claim 1, characterized in that, The hardware computing module's computing circuit also includes switching circuits and logic operation circuits. The first terminal of the switching circuit is electrically connected to one input terminal of the current detection module, the second terminal of the switching circuit is electrically connected to the first terminal of the logic operation circuit, the second terminal of the logic operation circuit is electrically connected to the output terminal of the voltage detection module, and the other terminal of the overcurrent state lockout circuit is electrically connected to the second terminal of the switching circuit.

7. The overvoltage, undervoltage, and overcurrent protection circuit according to claim 6, characterized in that, The switching circuit includes a PMOS transistor, an NPN transistor, and a diode; the logic operation circuit includes an undervoltage detection diode and an overvoltage detection diode. The source of the PMOS transistor is electrically connected to an input terminal of the current detection module, the drain of the PMOS transistor is electrically connected to the load circuit, the gate of the PMOS transistor is electrically connected to the collector of the NPN transistor, the emitter of the NPN transistor is grounded, and the base of the NPN transistor is electrically connected to the negative terminal of the diode. The negative terminal of the undervoltage detection diode is electrically connected to one output terminal of the voltage detection module, the positive terminal of the undervoltage detection diode is electrically connected to the positive terminal of the diode in the switching circuit, the negative terminal of the overvoltage detection diode is electrically connected to the other output terminal of the voltage detection module, and the positive terminal of the overvoltage detection diode is electrically connected to the positive terminal of the diode in the switching circuit.

8. The overvoltage, undervoltage, and overcurrent protection circuit according to claim 1, characterized in that, The overcurrent state lockout circuit includes a first resistor, a second resistor, a third resistor, a fourth resistor, a first diode, a second diode, a PNP transistor, and an NPN transistor. One end of the first resistor is connected to the reference power supply, and the other end is electrically connected to the anode of the first diode. The cathode of the first diode is electrically connected to one end of the second resistor and the collector of the PNP transistor. The other end of the second resistor is electrically connected to the base of the NPN transistor. The emitter of the NPN transistor is grounded. The collector of the NPN transistor is electrically connected to the cathode of the second diode and one end of the third resistor. The other end of the third resistor is electrically connected to the base of the PNP transistor. The emitter of the PNP transistor is connected to the reference power supply. The anode of the second diode is electrically connected to one end of the fourth resistor, and the other end of the fourth resistor is connected to the reference power supply.

9. A switching power supply, characterized in that, The switching power supply includes the overvoltage, undervoltage, and overcurrent protection circuits as described in claims 1-8 to control the power supply circuit.

10. An electronic device, characterized in that, The electronic device includes the switching power supply as described in claim 9.

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