Self-recovery protection circuit for output short circuit of direct-current stabilized power supply and design method

Abstract

The invention discloses a self-recovery protection circuit for output short circuit of a direct-current stabilized power supply, which comprises a voltage detection circuit and a voltage maintaining circuit, signals of the voltage detection circuit and the voltage maintaining circuit enter a voltage comparison circuit, and signals of the voltage comparison circuit enter a short-circuit signal generation circuit. The short-circuit signal generation circuit is connected with the pulse timing circuit and the short-circuit recovery signal generation circuit; a signal of the short-circuit recovery signal generation circuit enters the voltage comparison circuit; the invention also discloses a design method of the self-recovery protection circuit. The design method comprises the following steps: 1) selecting resistance and capacitance parameters in the voltage detection circuit; the short-circuit recovery signal generation circuit has the advantages that the safety performance of the circuit can be greatly improved, and the short-circuit recovery signal generation circuit has the advantage that output short-circuit protection can be timely and effectively carried out on the voltage-stabilized power supply.

Description

Technical Field

[0001] This invention belongs to the field of power supply technology, specifically relating to a self-resetting protection circuit for short circuits in the output of a DC regulated power supply, and also to a design method for the self-resetting protection circuit. Background Technology

[0002] Short-circuit protection of regulated power supplies is a challenging problem that may be encountered in practical applications for both linear and switching power supplies. How to provide timely and effective short-circuit protection is a crucial area of ​​research. Power supplies, as a critical component of systems, play a vital role in electronic equipment, from everyday electrical appliances like mobile phones and computers to large aircraft and ships. They are generally classified into AC and DC power supplies. Power supplies provide reliable and stable operating voltages to other operating systems. Under normal circumstances, power supplies operate normally. However, in abnormal operating conditions or special application environments, output short circuits may occur, generating very large short-circuit currents. If protection is not provided in time, serious consequences such as power supply failure or damage to downstream systems may result, causing significant losses.

[0003] DC regulated power supplies provide a stable DC operating voltage for a system. Based on the connection method between the power supply and the load, they are classified into series regulated power supplies and parallel regulated power supplies; based on the operating state of the regulating transistor, they are classified into linear regulated power supplies and switching regulated power supplies; based on the adjustment method, they are classified into simple regulated power supplies and feedback-regulated power supplies, etc. Currently, the most commonly used DC regulated power supply implementations are linear adjustment and switching power supply adjustment. Linear adjustment regulates the output voltage through the linear adjustment characteristics of the regulating transistor, offering advantages such as low output voltage ripple and simple adjustment circuitry, but also disadvantages such as narrow output voltage adjustment range and limited output power. Switching power supplies use pulse width modulation (PWM) technology to transform the input voltage into a high-frequency pulse, which is then passed through an output filter circuit to obtain the required DC voltage. They offer advantages such as flexible adjustment, wide output voltage range, and high power density, but also disadvantages such as larger output ripple voltage and more complex parameter design.

[0004] Currently, output short-circuit protection circuits include digital protection, analog protection, and self-resetting fuse protection, among others. Digital protection is widely used in fully digital control power supply systems. The equivalent resistance of self-resetting fuses changes, making subsequent matching difficult. Analog protection circuits are well-suited for hybrid analog-digital power supply systems due to their simplicity, stability, and reliability, but they also suffer from complex overall circuitry and lack of self-resetting capabilities or poor self-resetting performance. Summary of the Invention

[0005] The purpose of this invention is to provide a self-resetting protection circuit for output short circuit of a DC regulated power supply, which has the characteristics of timely and effective output short circuit protection for the regulated power supply.

[0006] Another objective of this invention is to provide a design method for a self-resetting protection circuit for a short circuit in the output of a DC regulated power supply.

[0007] The technical solution adopted in this invention is a self-recovery protection circuit for short circuit of DC regulated power supply output, including a voltage detection circuit and a voltage sustaining circuit. The signals from the voltage detection circuit and the voltage sustaining circuit enter the voltage comparison circuit. The signal from the voltage comparison circuit enters the short circuit signal generation circuit. The short circuit signal generation circuit is connected to a pulse timing circuit and a short circuit recovery signal generation circuit. The signal from the short circuit recovery signal generation circuit enters the voltage comparison circuit.

[0008] The invention is further characterized by:

[0009] The voltage sustaining circuit includes a diode D1 and a capacitor C1. The anode of diode D1 is connected to the positive terminal of the circuit, and the cathode of diode D1 is connected to capacitor C1. The other end of capacitor C1 is connected to the negative terminal of the circuit. The voltage sustaining circuit also includes resistors R5 and R7. The left end of resistor R5 is connected between diode D1 and capacitor C1, the right end of resistor R5 is connected to the upper end of resistor R7, and the lower end of resistor R7 is connected to the negative terminal of the circuit.

[0010] The voltage detection circuit includes resistors R2 and R8. The upper end of resistor R2 is connected to the positive terminal of the circuit, the lower end of resistor R2 is connected to the upper end of resistor R8, and the lower end of resistor R8 is connected to the negative terminal of the circuit.

[0011] The voltage comparison circuit includes comparator U1. The input terminal IN- of comparator U1 is connected between resistors R5 and R7, and the input terminal IN+ of comparator U1 is connected between resistors R2 and R8. The output terminal Vout of comparator U1 is connected to pin 2 of NE555 in the short-circuit signal generation circuit.

[0012] The short-circuit recovery signal generation circuit includes diode D2, resistor R9, and resistor R10. The upper end of resistor R9 is connected to the circuit of resistor R6 and capacitor C2, and the lower end of resistor R9 is connected to the upper end of resistor R10. The lower end of resistor R10 is grounded. The positive terminal of diode D2 is connected to the circuit between resistor R9 and resistor R10, and the negative terminal of diode D2 is connected to the circuit between resistor R2 and resistor R8. Moreover, compared to the input terminal IN+ of comparator U1, the connection point of the circuit between resistor R2 and resistor R8 is closer to the upper end of resistor R8.

[0013] The pulse timing circuit includes a resistor R3 and a capacitor C3. The upper end of the resistor R3 is connected to the positive terminal of the circuit, and the lower end of the resistor R3 is connected to the capacitor C3. The other end of the capacitor C3 is connected to the negative terminal of the self-resetting protection circuit.

[0014] The short-circuit signal generation circuit also includes capacitor C4. Pin 3 of NE555 outputs a high level. Pin 4 of NE555 is connected to the upper end of capacitor C2. Pin 5 of NE555 is connected to the upper end of capacitor C4. The lower end of capacitor C4 is connected to the negative terminal of the self-resetting protection circuit. Pin 6 of NE555 is connected to the lower end of resistor R3. Pin 7 of NE555 is connected to the lower end of resistor R3 and its connection position is far away from the connection position of pin 6.

[0015] Another technical solution adopted in this invention is a design method for a self-resetting protection circuit for a short circuit at the output of a DC regulated power supply, which is implemented according to the following steps: Step 1: Select the resistor and capacitor parameters in the voltage detection circuit; Step 2: Select the comparator U1 parameters; Step 3: Select the values ​​of the time-setting resistor R3 and capacitor C3 for the monostable multivibrator U2 to determine the duration of the high-level output of the monostable circuit. ; Step 4: Select the voltage divider network for the short-circuit recovery signal generation circuit.

[0016] Another feature of the technical solution of this invention is that: The resistor and capacitor parameters selected in step 1 satisfy the formula: , In the formula, V1 is the voltage after voltage division by resistors R5 and R7, and V2 is the voltage after voltage division by resistors R2 and R8. The parameters of comparator U1 in step 2 satisfy the following formula: , In the formula, V cc U is the power supply voltage. oH To identify a valid high level for the NE555, I oH I is the leakage current when the NE555 is at a high level. oL This is the maximum sink current of the comparator.

[0017] In step 3, the high-level output time of the monostable multivibrator U2 and the parameters of resistor R3 and capacitor C3 satisfy the following formula: , In the formula, This is the duration for the monostable multivibrator U2 to output a high level. The parameters of the circuit elements in the voltage divider network in step 4 satisfy the following formula: , In the formula, V2 is the voltage after voltage division by resistors R2 and R8, and V3 is the voltage after voltage division by resistors R9 and R10.

[0018] The beneficial effects of this invention are: (1) It can monitor the output status of the DC regulated power supply in real time, and quickly start the protection mechanism when a short circuit fault is detected, effectively cut off or limit the short circuit current, and prevent the power supply and load equipment from being damaged due to overcurrent.

[0019] (2) It has an automatic recovery function. After the short circuit fault is eliminated, the circuit can restore normal power supply on its own without manual intervention, which significantly improves the continuity and availability of the power supply system.

[0020] (3) A systematic design method is provided to guide the selection and parameter configuration of key components in the protection circuit, so that the circuit can take into account both sensitive protection response and stable normal operation.

[0021] (4) The circuit structure is simple and reliable, and it is easy to integrate with existing DC regulated power supplies. Without significantly increasing the cost and complexity, it enhances the power supply's self-protection capability and long-term working stability.

[0022] (5) With adjustable protection threshold and delay settings, the circuit can adapt to DC power supply systems with different power levels and load characteristics, and has good versatility and scalability. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the self-recovery protection circuit for short circuits in the output of a DC regulated power supply according to the present invention; Figure 2 This is a schematic diagram of the self-recovery protection circuit for short circuit of DC regulated power supply output in Embodiment 2 of the present invention; Figure 3 This is a schematic diagram of the self-recovery protection flyback circuit for short circuit protection of DC regulated power supply output in Embodiment 3 of the present invention; Figure 4 This is a waveform diagram of the characteristic signal of short circuit occurrence in this invention; Figure 5 This is a waveform diagram of the low active trigger signal output by the comparator after a short circuit is detected in this invention; Figure 6 This is a waveform diagram of the blocking pulse signal output by the NE555 of this invention.

[0024] In the diagram, 1 is the voltage sustaining circuit; 2 is the voltage detection circuit; 3 is the voltage comparison circuit; 4 is the short-circuit recovery signal generation circuit; 5 is the pulse timing circuit; and 6 is the short-circuit signal generation circuit. Detailed Implementation

[0025] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. The described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] Example 1 like Figure 1 As shown, the self-recovery protection circuit for short circuit output of DC regulated power supply provided by the present invention mainly consists of six parts: voltage maintenance circuit 1, voltage detection circuit 2, voltage comparison circuit 3, short circuit recovery signal generation circuit 4, pulse timing circuit 5, and short circuit signal generation circuit 6.

[0027] The signals from voltage detection circuit 2 and voltage sustaining circuit 1 enter voltage comparison circuit 3. Voltage comparison circuit 3 compares the input signal and generates a short-circuit signal of a certain width. The short-circuit signal drives the blocking circuit, and the circuit is cut off. At the same time, short-circuit recovery signal generation circuit 4 takes effect and generates a recovery pulse that acts on voltage comparison circuit 3. The voltage comparator resumes operation, the level is reversed, and the circuit starts working.

[0028] This self-resetting protection circuit overcomes the shortcomings of conventional circuits, such as the lack of self-resetting protection and inconsistent protection time.

[0029] Example 2 like Figure 2 As shown, in this embodiment, voltage maintenance circuit 1 is connected to voltage detection circuit 2, voltage detection circuit 2 is connected to voltage comparison circuit 3, voltage comparison circuit 3 is connected to short-circuit recovery signal generation circuit 4 and pulse timing circuit 5, and pulse timing circuit 5 is connected to short-circuit signal generation circuit 6. The circuit between voltage comparison circuit 3 and pulse timing circuit 5 includes resistors R1, R4, and R6, and capacitor C2. The upper end of resistor R1 is connected to the VCC power line, and the lower end of resistor R1 is connected to the output of comparator U1 and the TRIG pin connection line of NE555. The upper end of resistor R4 is connected to pulse timing circuit 5, and the lower end of resistor R4 is connected to capacitor C2. The other end of capacitor C2 is connected to the negative terminal of the self-recovery protection circuit, and resistor R6 is connected in parallel with capacitor C2.

[0030] The voltage sustaining circuit 1 includes a diode D1 and a capacitor C1, as well as resistors R5 and R7. The anode of diode D1 is connected to the anode of the self-resetting protection circuit, the cathode of diode D1 is connected to capacitor C1, the other end of capacitor C1 is connected to the cathode of the self-resetting protection circuit, the left end of resistor R5 is connected between diode D1 and capacitor C1, the right end of resistor R5 is connected to the upper end of resistor R7, and the lower end of resistor R7 is connected to the cathode of the self-resetting protection circuit.

[0031] The voltage detection circuit 2 includes resistors R2 and R8 in a voltage divider circuit. The upper end of resistor R2 is connected to the positive terminal of the self-resetting protection circuit, the lower end of resistor R2 is connected to the upper end of resistor R8, and the lower end of resistor R8 is connected to the negative terminal of the self-resetting protection circuit.

[0032] The voltage comparison circuit 3 includes a comparator U1. The input terminal IN- of the comparator U1 is connected between resistors R5 and R7, the input terminal IN+ of the comparator U1 is connected between resistors R2 and R8, and the output terminal Vout of the comparator U1 is connected to pin 2 of the NE555.

[0033] The short-circuit recovery signal generation circuit 4 includes a voltage divider short circuit and an anti-reverse current diode D2, as well as resistors R9 and R10 and diode D2. The upper end of resistor R9 is connected to the circuit of resistor R6 and capacitor C2, and the lower end of resistor R9 is connected to the upper end of resistor R10. The lower end of resistor R10 is grounded. The positive terminal of diode D2 is connected to the circuit between resistors R9 and R10, and the negative terminal of diode D2 is connected to the circuit between resistors R2 and R8. Moreover, compared to the input terminal IN+ of comparator U1, the connection point of the circuit between resistors R2 and R8 is closer to the upper end of resistor R8.

[0034] The pulse timing circuit 5 includes a resistor R3 and a capacitor C3. The upper end of the resistor R3 is connected to the VCC power line, the lower end of the resistor R3 is connected to the capacitor C3, and the other end of the capacitor C3 is connected to the negative terminal of the self-resetting protection circuit. The short-circuit signal generation circuit 6 includes an NE555 and a capacitor C4. Pin 3 of the NE555 outputs a high level. Pin 4 of the NE555 is connected to the upper end of the capacitor C2. Pin 5 of the NE555 is connected to the upper end of the capacitor C4. The lower end of the capacitor C4 is connected to the negative terminal of the self-resetting protection circuit. Pin 6 of the NE555 is connected to the lower end of the resistor R3. Pin 7 of the NE555 is connected to the lower end of the resistor R3, and its connection position is far away from the connection position of pin 6.

[0035] Under normal operating conditions without a short circuit, the voltage at the non-inverting terminal of comparator U1 is higher than that at the inverting terminal, and comparator U1 outputs a high level; Reference Figures 4-6 As shown, when a short circuit occurs at the output, the voltage at the inverting terminal is maintained by the voltage sustaining circuit 1, resulting in a low output level. This triggers the low-active-value NE555 monostable circuit, which outputs a continuous blocking pulse for a certain period of time. At this time, the short-circuit recovery signal generation circuit 4 acts on the non-inverting terminal of the comparator U1 through diode D2. The voltage at the non-inverting terminal is higher than that at the inverting terminal, so the voltage comparator circuit 3 outputs a high level, and the output level of the monostable NE555 circuit flips. If the short circuit is released, the output signal of the entire circuit is restored in time.

[0036] Example 3 like Figure 3As shown, this embodiment is a flyback switching converter power supply, including a self-resetting protection circuit and a PWM controller circuit. The self-resetting protection circuit is connected to the PWM controller circuit through a transformer T1. The PWM controller circuit consists of a PWM controller and resistors R0 and Rg. The upper end of resistor R0 is connected to the VCC power line, and the lower end of resistor R0 is connected to the PWM controller. The PWM controller is a UC38xx series. The Is terminal of the PWM controller is connected to pin 3 of the NE555 chip. The OUT terminal of the PWM controller outputs a pulse signal. The OUT terminal of the PWM controller is connected to the left end of resistor Rg, and the right end of resistor Rg is connected to the gate of Q1. The resistance of resistor Rg is 20Ω.

[0037] The voltage sustaining circuit 1 includes a diode D1 and a capacitor C1, as well as resistors R5 and R7. The anode of diode D1 is connected to the anode of the self-resetting protection circuit, and the cathode of diode D1 is connected to capacitor C1. The other end of capacitor C1 is connected to the cathode of the self-resetting protection circuit. The left end of resistor R5 is connected between diode D1 and capacitor C1, the right end of resistor R5 is connected to the upper end of resistor R7, and the lower end of resistor R7 is connected to the cathode of the self-resetting protection circuit. In this embodiment, diode D1 is an IN4007, capacitor C1 is a 107, resistor R5 has a resistance of 30kΩ, and resistor R7 has a resistance of 10kΩ.

[0038] The voltage detection circuit 2 includes resistors R2 and R8 in a voltage divider circuit. The upper end of resistor R2 is connected to the positive terminal of the self-resetting protection circuit, and the lower end of resistor R2 is connected to the upper end of resistor R8. The lower end of resistor R8 is connected to the negative terminal of the self-resetting protection circuit. In this embodiment, the resistance value of resistor R2 is 20kΩ and the resistance value of resistor R8 is 10kΩ.

[0039] The voltage comparison circuit 3 includes a comparator U1. The input terminal IN- of the comparator U1 is connected between resistors R5 and R7, the input terminal IN+ of the comparator U1 is connected between resistors R2 and R8, and the output terminal Vout of the comparator U1 is connected to pin 2 of the NE555.

[0040] The short-circuit recovery signal generation circuit 4 includes a voltage divider short circuit and an anti-reverse-current diode D2, as well as resistors R9 and R10 and diode D2. The upper end of resistor R9 is connected to the circuit of resistor R6 and capacitor C2, and the lower end of resistor R9 is connected to the upper end of resistor R10. The lower end of resistor R10 is grounded. The positive terminal of diode D2 is connected to the circuit between resistors R9 and R10, and the negative terminal of diode D2 is connected to the circuit between resistors R2 and R8. Compared to the input terminal IN+ of comparator U1, the connection point between resistors R2 and R8 is closer to the upper end of resistor R8. In this embodiment, resistor D2 is an IN4007, the resistance of resistor R9 is 10kΩ, and the resistance of resistor R10 is 1kΩ.

[0041] The pulse timing circuit 5 includes a resistor R3 and a capacitor C3. The upper end of the resistor R3 is connected to the VCC power line, and the lower end of the resistor R3 is connected to the capacitor C3. The other end of the capacitor C3 is connected to the negative terminal of the self-resetting protection circuit. In this embodiment, the resistance of the resistor R3 is 1kΩ, and the capacitor C3 is a 105 capacitor.

[0042] The short-circuit signal generation circuit 6 includes an NE555 timer and a capacitor C4. Pin 3 of the NE555 timer is connected to the Is terminal of the PWM controller. Pin 4 of the NE555 timer is connected to the upper end of the capacitor C2. Pin 5 of the NE555 timer is connected to the upper end of the capacitor C4. The lower end of the capacitor C4 is connected to the negative terminal of the self-resetting protection circuit. Pin 6 of the NE555 timer is connected to the lower end of the resistor R3. Pin 7 of the NE555 timer is connected to the lower end of the resistor R3, and the connection position is far away from the connection position of pin 6. In this embodiment, the model of C4 is 102.

[0043] Under normal operating conditions without a short circuit, the voltage at the non-inverting terminal of comparator U1 is higher than that at the inverting terminal, and comparator U1 outputs a high level. When a short circuit occurs at the output, the voltage at the inverting terminal is maintained by voltage sustaining circuit 1, resulting in a low-level output. This triggers the low-active-weight NE555 monostable circuit, which outputs a continuous blocking pulse for a certain period of time to the PWM controller. The PWM controller stops outputting pulses and no longer transmits energy to the short-circuited terminal. At this time, the short-circuit recovery signal generation circuit 4 acts on the non-inverting terminal of the comparator through diode D2. The voltage at the non-inverting terminal is higher than that at the inverting terminal, and the comparator circuit outputs a high level. The monostable NE555 circuit flips the signal to trigger the PWM controller again. If the short circuit is cleared, the entire circuit restores power supply in a timely manner.

[0044] Example 4 The design method of the self-resetting protection circuit for short circuit of DC regulated power supply output in this embodiment includes the following steps: Step 1: Select the resistor and capacitor parameters in voltage detection circuit 2; Step 2: Select the comparator U1 parameters; Step 3: Select the time of the monostable multivibrator U2, set the values ​​of resistor R3 and capacitor C3, and determine the duration of the high-level output of the monostable circuit. ; Step 4: Select the voltage divider network of the short-circuit recovery signal generation circuit 4.

[0045] Example 5 The design method of the self-resetting protection circuit for short circuit of DC regulated power supply output in this embodiment includes the following steps: Step 1: Select the resistor and capacitor parameters in voltage detection circuit 2. The specific selection principle is that capacitor C1 is charged through diode D1, and the voltage at the inverting terminal of comparator U1 after voltage division by resistors R5 and R7 is lower than the voltage divided by resistors R2 and R8. Step 2: Select the parameters of comparator U1; the specific principle is that after setting the parameters of pull-up resistor R1, the power supply range of comparator U2 should be within the effective low-level trigger voltage range of the subsequent NE555 flip-flop, and the parameters of pull-up resistor R1 should be able to provide a matching operating current. Step 3: Select the values ​​of the time-setting resistor R3 and capacitor C3 for the monostable multivibrator U2 to determine the duration of the high-level output of the monostable circuit. The values ​​of resistor R3 and capacitor C3 can be determined based on the required high-level time. Step 4: Select the voltage divider network for the short-circuit recovery signal generation circuit 4; the parameters of resistors R9 and R10 and diode D2 in the voltage divider network are as follows: Under normal conditions without a short circuit, the voltage divider effect of resistors R9 and R10 on diode D2 results in an anode voltage lower than the cathode voltage, and the diode does not conduct. When a short circuit fault occurs, the voltage divided by the voltage divider network on the anode of diode D2 is greater than the cathode voltage, the diode conducts, and the voltage is applied to the non-inverting input of comparator U2.

[0046] Example 6 The design method of the self-resetting protection circuit for short circuit of DC regulated power supply output in this embodiment is as follows: Step 1: Select the resistor and capacitor parameters for the detection circuit. The specific principle is that capacitor C1 is charged through diode D1, and the voltage at the inverting terminal of comparator U1 after voltage division by resistors R5 and R7 is lower than the voltage division by resistors R2 and R8. The parameters of the above components satisfy the following formula (1): (1) In the formula, V1 is the voltage after voltage division by resistors R5 and R7, and V2 is the voltage after voltage division by resistors R2 and R8.

[0047] Step 2: Select the parameters of comparator U1. Specifically, the parameters of pull-up resistor R1 should be selected. The power supply range of monostable multivibrator U2 should be within the effective low-level trigger voltage range of the subsequent NE555 multivibrator. After selecting the parameters of pull-up resistor R1, it should be able to provide a matching operating current. The value range of the above component parameters is shown in equation (2): (2) In the formula, V cc U is the power supply voltage. oH For the subsequent NE555 chip to identify a valid high level, I oH I is the leakage current of the NE555 chip when it is at a high level. oL This is the maximum sink current of the comparator.

[0048] Step 3: Select the values ​​of the time-setting resistor R3 and capacitor C3 for the monostable multivibrator U2 to determine the duration of the high-level output of the monostable multivibrator U2. The time calculation formula is shown in (3): (3) The values ​​of resistors and capacitors can be determined based on the required high-level time.

[0049] Step 4: Select the voltage divider network for the recovery circuit, including the parameters of resistors R9 and R10 and diode D2. Under normal conditions without a short circuit, the voltage divider effect of resistors R9 and R10 on diode D2 results in a lower anode voltage than cathode voltage, and the diode does not conduct. When a short circuit occurs, the voltage divider effect on the anode of D2 is greater than the cathode voltage, the diode conducts, and the voltage is applied to the non-inverting input of comparator U2. The parameters of the above components satisfy the calculation formula as shown in (4): (4) In the formula, V2 is the voltage after voltage division by resistors R2 and R8, and V3 is the voltage after voltage division by resistors R9 and R10.

[0050] By following the above steps and the selection principles for the parameters of each component in the circuit, the self-recovery protection circuit for short circuits in the output of a DC regulated power supply can be designed.

Claims

1. A self-resetting protection circuit for short circuits at the output of a DC regulated power supply, characterized in that, The circuit includes a voltage detection circuit (2) and a voltage sustaining circuit (1). The signals from the voltage detection circuit (2) and the voltage sustaining circuit (1) enter the voltage comparison circuit (3). The signals from the voltage comparison circuit (3) enter the short-circuit signal generation circuit (6). The short-circuit signal generation circuit (6) is connected to the pulse timing circuit (5) and the short-circuit recovery signal generation circuit (4). The signals from the short-circuit recovery signal generation circuit (4) enter the voltage comparison circuit (3).

2. The self-resetting protection circuit for short circuit at the output of a DC regulated power supply according to claim 1, characterized in that, The voltage sustaining circuit (1) includes a diode D1 and a capacitor C1. The positive terminal of the diode D1 is connected to the positive terminal of the circuit, and the negative terminal of the diode D1 is connected to the capacitor C1. The other end of the capacitor C1 is connected to the negative terminal of the circuit. The voltage sustaining circuit (1) also includes a resistor R5 and a resistor R7. The left end of the resistor R5 is connected between the diode D1 and the capacitor C1, the right end of the resistor R5 is connected to the upper end of the resistor R7, and the lower end of the resistor R7 is connected to the negative terminal of the circuit.

3. The self-resetting protection circuit for short circuit at the output of a DC regulated power supply according to claim 1, characterized in that, The voltage detection circuit (2) includes resistor R2 and resistor R8. The upper end of resistor R2 is connected to the positive terminal of the circuit, the lower end of resistor R2 is connected to the upper end of resistor R8, and the lower end of resistor R8 is connected to the negative terminal of the circuit.

4. The self-resetting protection circuit for short circuit at the output of a DC regulated power supply according to claim 1, characterized in that, The voltage comparison circuit (3) includes a comparator U1. The input terminal IN- of the comparator U1 is connected between resistors R5 and R7, the input terminal IN+ of the comparator U1 is connected between resistors R2 and R8, and the output terminal Vout of the comparator U1 is connected to pin 2 of the NE555 in the short-circuit signal generation circuit (6).

5. The self-resetting protection circuit for short circuit at the output of a DC regulated power supply according to claim 1, characterized in that, The short-circuit recovery signal generation circuit (4) includes a diode D2, a resistor R9 and a resistor R10. The upper end of the resistor R9 is connected to the circuit of the resistor R6 and the capacitor C2. The lower end of the resistor R9 is connected to the upper end of the resistor R10. The lower end of the resistor R10 is grounded. The positive terminal of the diode D2 is connected to the circuit between the resistor R9 and the resistor R10. The negative terminal of the diode D2 is connected to the circuit between the resistor R2 and the resistor R8. The connection point of the circuit between the resistor R2 and the resistor R8 is closer to the upper end of the resistor R8 than the input terminal IN+ of the comparator U1.

6. The self-resetting protection circuit for short circuit at the output of a DC regulated power supply according to claim 1, characterized in that, The pulse timing circuit (5) includes a resistor R3 and a capacitor C3. The upper end of the resistor R3 is connected to the positive terminal of the circuit, the lower end of the resistor R3 is connected to the capacitor C3, and the other end of the capacitor C3 is connected to the negative terminal of the self-resetting protection circuit.

7. The self-resetting protection circuit for short circuit at the output of a DC regulated power supply according to claim 4 or 5, characterized in that, The short-circuit signal generation circuit (6) also includes capacitor C4, pin 3 of NE555 outputs a high level, pin 4 of NE555 is connected to the upper end of capacitor C2, pin 5 of NE555 is connected to the upper end of capacitor C4, the lower end of capacitor C4 is connected to the negative terminal of the self-resetting protection circuit, pin 6 of NE555 is connected to the lower end of resistor R3, and pin 7 of NE555 is connected to the lower end of resistor R3 and the connection position is far away from the connection position of pin 6.

8. A design method for a self-resetting protection circuit for a short circuit at the output of a DC regulated power supply, wherein the self-resetting protection circuit for a short circuit at the output of a DC regulated power supply according to any one of claims 1-7 is characterized in that, The specific steps are as follows: Step 1: Select the resistance and capacitance parameters in the voltage detection circuit (2); Step 2: Select the comparator U1 parameters; Step 3: Select the values ​​of the time-setting resistor R3 and capacitor C3 for the monostable multivibrator U2 to determine the duration of the high-level output of the monostable circuit. ; Step 4: Select the voltage divider network of the short-circuit recovery signal generation circuit (4).

9. The design method of the self-resetting protection circuit for short circuit of DC regulated power supply output according to claim 8, characterized in that, The resistor and capacitor parameters selected in step 1 satisfy the formula: ， In the formula, V1 is the voltage after voltage division by resistors R5 and R7, and V2 is the voltage after voltage division by resistors R2 and R8. The parameters of comparator U1 in step 2 satisfy the following formula: ， In the formula, V cc U is the power supply voltage. oH To identify a valid high level for the NE555, I oH I is the leakage current when the NE555 is at a high level. oL This is the maximum sink current of the comparator.

10. The design method of the self-resetting protection circuit for short circuit of DC regulated power supply output according to claim 8, characterized in that, In step 3, the high-level output time of the monostable multivibrator U2 and the parameters of resistor R3 and capacitor C3 satisfy the following formula: ， In the formula, This is the duration for the monostable multivibrator U2 to output a high level. The parameters of the circuit elements in the voltage divider network in step 4 satisfy the following formula: ， In the formula, V2 is the voltage after voltage division by resistors R2 and R8, and V3 is the voltage after voltage division by resistors R9 and R10.

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