Switching power supply with overvoltage self-protection

Abstract

The utility model discloses a switching power supply with overvoltage self-protection, which comprises a master control IC1 used for outputting PWM (Pulse Width Modulation) signals; the voltage stabilization output unit is used for obtaining the PWM signal and then carrying out voltage stabilization processing on the voltage; the overvoltage self-protection unit is used for detecting the power supply voltage and performing overvoltage protection on the master control IC1; the overvoltage self-protection unit comprises a resistor R11, a resistor R12, a resistor R13, a triode Q2 and a diode IC2, one end of the resistor R11 is connected with one end of the resistor R12, the other end of the resistor R12 is connected to a base electrode of the triode Q2 through the diode IC2, a pin R of the diode IC2 is connected between the resistor R11 and the resistor R12, and one end of the resistor R13 is connected to the voltage stabilization output unit. The switching power supply with overvoltage self-protection can input overvoltage automatic protection, and the input overvoltage protection voltage value is adjustable.

Description

Technical Field

[0001] This utility model relates to the field of switching power supply technology, specifically to a switching power supply with overvoltage self-protection. Background Technology

[0002] Early switching power supplies lacked overvoltage protection for AC input voltage. When market and end-customer demands a solution, design engineers had to design input overvoltage protection circuits, which were prone to misjudgment. Furthermore, the non-adjustable input overvoltage protection value made it difficult to meet market requirements. Disadvantages: Due to the lack of input voltage protection circuitry or inadequate protection, the power supply's main power components could easily explode, potentially damaging downstream loads (electronic equipment), causing personal injury, and in severe cases, even leading to a fire. Utility Model Content

[0003] The purpose of this invention is to provide a switching power supply with overvoltage self-protection.

[0004] To achieve the above objectives, this utility model provides the following technical solution: a switching power supply with overvoltage self-protection, comprising:

[0005] The main control IC1 is used to output a PWM signal after obtaining power.

[0006] The voltage regulator output unit is used to obtain the PWM signal, regulate the voltage, and then provide a stable operating voltage to the main control IC1; and

[0007] The overvoltage self-protection unit is used to detect the power supply voltage and provide overvoltage protection for the main control IC1;

[0008] The overvoltage self-protection unit includes resistors R11, R12, and R13, transistor Q2, and diode IC2. One end of resistor R11 is connected to one end of R12, and the other end of resistor R12 is connected to the base of transistor Q2 through diode IC2. The R-pin of diode IC2 is connected between resistors R11 and R12, and one end of resistor R13 is connected to the voltage regulation output unit.

[0009] Furthermore, it also includes a power supply unit for supplying power to the main control IC1. The power supply unit includes a rectifier bridge DB1, a capacitor EC1, resistors R1 and R2, and an electrolytic capacitor EC3. The rectifier bridge DB1 is connected to the GND terminal of the main control IC1 through the capacitor EC1. The resistors R1 and R2 are connected in series, with one end connected to the capacitor EC1 and the other end connected to the VDD terminal of the main control IC1. The electrolytic capacitor EC3 is connected to the VDD terminal of the main control IC1.

[0010] Furthermore, the regulated output unit includes:

[0011] A filter circuit used to obtain and filter PWM signals to output DC voltage.

[0012] A feedback loop circuit for stabilizing DC voltage at a set value; and

[0013] A rectifier and filter circuit used to rectify and filter the set DC voltage to provide a stable operating voltage for the main control IC1.

[0014] Furthermore, the filter circuit includes a MOSFET Q1, a transformer TR, a diode D6, and capacitors EC4 and EC5. The gate of the MOSFET Q1 is connected to the main control IC1, and the drain of the MOSFET Q1 is connected to the transformer TR. The transformer TR is connected to capacitors EC4 and EC5 in parallel, and the diode D6 is connected between the transformer TR and capacitor EC4.

[0015] Furthermore, the feedback loop circuit includes resistors R16, R17, R18, R19, R20, R21, a light-emitting diode PCA, a diode IC3, and a capacitor C6. One end of resistor R16 is connected to a filter circuit, and the other end of resistor R16 is connected to the anode of light-emitting diode PCA. The cathode of light-emitting diode PCA is connected to the cathode of diode IC3. One end of capacitor C6 is connected between PCA and IC3, and the other end of C6 is connected to one end of resistor R18. One end of resistor R17 is connected between PCA and R16, and the other end of resistor R17 is connected between PCA and C6. One end of resistor R19 is connected to the anode of IC3 through parallel connections R20 and R21, and the other end of resistor R18 is connected between R19 and R20.

[0016] Furthermore, the rectifier filter circuit includes a transformer VCC, a diode D2, and a capacitor EC2. The transformer VCC is connected to the overvoltage self-protection unit after passing through the diode D2 and the capacitor EC2 in series.

[0017] As can be seen from the above technical solution, this utility model has the following beneficial effects:

[0018] This switching power supply with overvoltage self-protection can automatically protect against input voltage overvoltage, and the input overvoltage protection voltage value is adjustable. Attached Figure Description

[0019] Figure 1 This is the overall circuit diagram of this utility model. Detailed Implementation

[0020] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0021] like Figure 1 As shown, this utility model provides a switching power supply with overvoltage self-protection, including a main control IC1, a power supply unit, a voltage regulation output unit, and an overvoltage self-protection unit. The power supply unit includes a rectifier bridge DB1, a capacitor EC1, resistors R1 and R2, and an electrolytic capacitor EC3. Pins 1 and 3 of the rectifier bridge DB1 are connected to the switching power supply through a transformer LF2 and a capacitor CX1 connected in parallel. Pins 2 and 4 of the rectifier bridge DB1 are connected to the two ends of the capacitor EC1 and then connected to the GND terminal (pin 1) of the main control IC1. The electrolytic capacitor EC3 is connected to the VDD terminal (pin 5) of the main control IC1. Resistors R1 and R2 are connected in series, with one end connected to the capacitor EC1 and the other end connected between the electrolytic capacitor EC3 and the main control IC1.

[0022] When the AC voltage is connected to the input terminal of the switching power supply, it is rectified by the rectifier bridge DB1 and then filtered by the capacitor EC1, so that the voltage across the capacitor EC1 is a DC voltage of 1.3-1.4 times the input voltage. The electrolytic capacitor EC3 is charged through resistors R1 and R2. When the voltage on EC3 rises to about DC18V, the power control main control IC1 starts to work, and pin 6 of the main control IC1 starts to output a PWM signal.

[0023] The voltage regulation output unit includes a filter circuit, a feedback loop circuit, and a rectifier filter circuit. The filter circuit includes a MOSFET Q1, a transformer TR, a diode D6, and capacitors EC4 and EC5. The gate of the MOSFET Q1 is connected to pin 6 of the main control IC1 through a parallel connection of diode D4, resistors R6 and R7. The source of the MOSFET Q1 is connected to pin 4 of the main control IC1 through a parallel connection of resistors R9, R8, and C3. The parallel connection of resistors R9, R8, and C3 is connected to pin 2 of the main control IC1 through a parallel connection of transistor PCB and capacitor C2. The drain of the MOSFET Q1 is connected to the P1 terminal of the transformer TR through a diode D1, a parallel connection of resistors R3 and R4, capacitors C1 and R5. The S1 terminal of the transformer TR is connected to the parallel connection of capacitors EC4 and EC5. The diode D6 is connected between the transformer TR and capacitor EC4.

[0024] The feedback loop circuit includes resistors R16, R17, R18, R19, R20, and R21, a light-emitting diode PCA, a diode IC3, and a capacitor C6. One end of resistor R16 is connected between capacitors EC4 and EC5, and the other end of resistor R16 is connected to the anode of light-emitting diode PCA. The cathode of light-emitting diode PCA is connected to the cathode of diode IC3. One end of capacitor C6 is connected between PCA and IC3, and the other end of C6 is connected to one end of resistor R18. One end of resistor R17 is connected between PCA and R16, and the other end of resistor R17 is connected between PCA and C6. One end of resistor R19 is connected to the anode of diode IC3 through parallel connections R20 and R21, and the other end of resistor R18 is connected between R19 and R20.

[0025] The rectifier and filter circuit includes a transformer VCC, a diode D2, and a capacitor EC2. The transformer VCC is connected to the overvoltage self-protection unit in series through the diode D2 and the capacitor EC2.

[0026] When pin 6 of the main control IC1 starts outputting a PWM signal, the switching MOSFET Q1 operates. At this time, the transformer TR transfers energy from the primary side to the secondary side through the proportional relationship between the P1 and S1 windings (voltage decreases, current increases). After rectification by D6 and filtering by the two electrolytic capacitors EC4 and EC5, a DC voltage is output. The feedback loop circuit stabilizes the power supply output voltage at the value set by the customer. The transformer VCC winding obtains a coupling voltage, which is rectified by D2 and filtered by the two electrolytic capacitors EC2 and EC3 to provide a stable operating voltage for the power control IC1.

[0027] The overvoltage self-protection unit includes resistors R11, R12, and R13, transistor Q2, and diode IC2. One end of resistor R11 is connected to one end of R12, and the other end of resistor R12 is connected to the base of transistor Q2 through diode IC2. The R-pin of diode IC2 is connected between resistors R11 and R12. One end of resistor R13 is connected to the cathode of diode IC2, and the other end of resistor R13 is connected to the collector of transistor Q2. However, the emitter of transistor Q2 is connected to pin 5 of the main control IC.

[0028] When the input AC voltage of the switching power supply experiences abnormal sudden changes due to power grid fluctuations or improper use, the voltage instantaneously rises above the rated value. At this time, the voltage across EC1 increases proportionally. Resistors R11, R12, and R13 divide the voltage, causing the voltage across R13 to rise. This leads to an increase in the voltage at pin R of IC2, while the voltage at pin K decreases proportionally to a low level. The base of transistor Q2 becomes low, and Q2 is turned off. The Vcc voltage of the main control IC1 drops. When the voltage is below 10V, the main control IC1 is turned off, and the power supply has no output. When the input AC voltage drops back to the rated voltage range, after being divided by resistors R11, R12, and R13, the voltage across R13 decreases. This leads to a decrease in the voltage at pin R of IC2, while the voltage at pin K increases proportionally to a high level. The base of transistor Q2 becomes high, and Q2 turns on and operates normally. The main control IC1 resumes operation, the power supply operates normally, and the output voltage is normal. By appropriately adjusting the ratio of the resistance values ​​of resistors R11, R12, and R13, the input overvoltage protection voltage value can be adjusted arbitrarily.

[0029] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A switching power supply with overvoltage self-protection, characterized in that, include: The main control IC1 is used to output a PWM signal after obtaining power. The voltage regulator output unit is used to obtain the PWM signal, regulate the voltage, and then provide a stable operating voltage to the main control IC1; and The overvoltage self-protection unit is used to detect the power supply voltage and provide overvoltage protection for the main control IC1. The overvoltage self-protection unit includes resistors R11, R12, and R13, transistor Q2, and diode IC2. One end of resistor R11 is connected to one end of R12, and the other end of resistor R12 is connected to the base of transistor Q2 through diode IC2. The R-pin of diode IC2 is connected between resistors R11 and R12, and one end of resistor R13 is connected to the voltage regulation output unit.

2. A switching power supply with overvoltage self-protection according to claim 1, characterized in that: It also includes a power supply unit for supplying power to the main control IC1. The power supply unit includes a rectifier bridge DB1, a capacitor EC1, resistors R1 and R2, and an electrolytic capacitor EC3. The rectifier bridge DB1 is connected to the GND terminal of the main control IC1 through the capacitor EC1. The resistors R1 and R2 are connected in series, with one end connected to the capacitor EC1 and the other end connected to the VDD terminal of the main control IC1. The electrolytic capacitor EC3 is connected to the VDD terminal of the main control IC1.

3. A switching power supply with overvoltage self-protection according to claim 1, characterized in that: The regulated output unit includes: A filter circuit used to obtain and filter PWM signals to output DC voltage. A feedback loop circuit for stabilizing DC voltage at a set value; and A rectifier and filter circuit used to rectify and filter the set DC voltage to provide a stable operating voltage for the main control IC1.

4. A switching power supply with overvoltage self-protection according to claim 3, characterized in that: The filter circuit includes a MOSFET Q1, a transformer TR, a diode D6, and capacitors EC4 and EC5. The gate of the MOSFET Q1 is connected to the main control IC1, and the drain of the MOSFET Q1 is connected to the transformer TR. The transformer TR is connected to capacitors EC4 and EC5 in parallel. The diode D6 is connected between the transformer TR and capacitor EC4.

5. A switching power supply with overvoltage self-protection according to claim 3, characterized in that: The feedback loop circuit includes resistors R16, R17, R18, R19, R20, R21, a light-emitting diode PCA, a diode IC3, and a capacitor C6. One end of resistor R16 is connected to a filter circuit, and the other end of resistor R16 is connected to the anode of light-emitting diode PCA. The cathode of light-emitting diode PCA is connected to the cathode of diode IC3. One end of capacitor C6 is connected between PCA and IC3, and the other end of C6 is connected to one end of resistor R18. One end of resistor R17 is connected between PCA and R16, and the other end of resistor R17 is connected between PCA and C6. One end of resistor R19 is connected to the anode of IC3 through parallel connections R20 and R21, and the other end of resistor R18 is connected between R19 and R20.

6. A switching power supply with overvoltage self-protection according to claim 3, characterized in that: The rectifier and filter circuit includes a transformer VCC, a diode D2, and a capacitor EC2. The transformer VCC is connected to the overvoltage self-protection unit via the diode D2 and the capacitor EC2 connected in series.

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