Switching power supply circuit with overvoltage protection

Abstract

The utility model discloses a switching power supply circuit with overvoltage protection, comprising a master control IC1 used for outputting a PWM signal; the voltage stabilization output unit is used for obtaining the PWM signal and then carrying out voltage stabilization processing on the voltage; and the overvoltage protection unit is used for detecting the voltage of the master control IC1 and performing overvoltage protection. The overvoltage protection unit comprises a transformer VCC and a resistor RV, and the transformer VCC is connected with the master control IC1 through the resistor RV. The switching power supply circuit with over-temperature protection is simple in circuit, adjustable in over-voltage value, high in output over-voltage protection precision, capable of flexibly controlling the specific over-voltage value of output voltage, capable of meeting market requirements and beneficial to safe production, and is a switching power supply with high reliability and high cost performance.

Description

Technical Field

[0001] The utility model relates to the technical field of switching power supplies, in particular to a switching power supply circuit with overvoltage protection. Background Art

[0002] Early switching power supplies lacked output overvoltage protection, or required designers to redesign the output overvoltage protection circuit. Furthermore, the circuit was prone to misjudgment and had large accuracy deviations, making it difficult to meet market demand. Disadvantages: Because the power supply output lacks overvoltage protection or has low overvoltage protection accuracy, downstream loads (electronic devices) can be easily damaged by a sudden increase in input voltage (the switching power supply's output voltage) exceeding the rated voltage. This can cause personal injury and, in severe cases, fire. Utility Model Content

[0003] The purpose of the utility model is to provide a switching power supply circuit with overvoltage protection.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a switching power supply circuit with overvoltage protection, comprising:

[0005] Main control IC1, used to output PWM signal;

[0006] A voltage stabilization output unit, used to stabilize the voltage after acquiring the PWM signal; and

[0007] The overvoltage protection unit is used to detect the voltage of the main control IC1 and perform overvoltage protection.

[0008] The overvoltage protection unit includes a transformer VCC and a resistor RV. The transformer VCC is connected to the main control IC1 through the resistor RV.

[0009] Furthermore, it also includes a power supply unit for powering the main control IC1, the power supply unit includes resistors R1, R2, R3, and capacitor EC3, one end of the capacitor EC3 is connected to the main control IC1, one end of the resistor R1 is connected to one end of R2, one end of the resistor R3 is connected between R1 and R2, and the other end of the resistor R3 is connected between the capacitor EC3 and the main control IC1.

[0010] Furthermore, the voltage stabilization output unit includes:

[0011] A filter circuit that obtains PWM signals, filters them, and then outputs a DC voltage.

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

[0013] A rectifier and filter circuit is used to rectify and filter DC voltage.

[0014] Furthermore, the filtering circuit includes a rectifier bridge DB1, a switch MOS tube Q1, a capacitor EC1, a transformer TR, a diode D5, and electrolytic capacitors EC4 and EC5. The rectifier bridge DB1 is connected to one end P1 of the transformer TR through the capacitor EC1, and the other end P1 of the transformer TR is connected to the drain of the switch MOS tube Q1. The S1 end of the transformer TR is connected to the parallel electrolytic capacitors EC4 and EC5 in sequence through the diode D5.

[0015] Furthermore, the feedback loop circuit includes resistors R13, R14, R15, R16, R17, a light-emitting diode PC1, a diode IC2, and a capacitor C6. One end of the resistor R13 is connected to the anode of the light-emitting diode PC1, and the cathode of the light-emitting diode PC1 is connected to the capacitors C6, R15, and R16 in sequence. One end of the resistor R14 is connected between R13 and PC1, and the other end of the resistor R14 is connected between the capacitor C6 and PC1. The cathode of the diode IC2 is connected to the cathode of PC1, and the resistor R17 is connected to the diode IC2.

[0016] Furthermore, the rectifier and filter circuit includes diodes D2 and D3, and a capacitor EC2. The anode of the diode D2 is connected to the overvoltage protection unit, the cathode of the diode D2 is connected to one end of the capacitor EC2, the anode of the diode D3 is connected between D2 and the capacitor EC2, the cathode of the diode D3 is connected to the capacitor EC3, and the capacitor EC3 is connected to the other end of the capacitor EC2.

[0017] It can be seen from the above technical solution that the utility model has the following beneficial effects:

[0018] The switching power supply circuit with over-temperature protection has a simple circuit, an adjustable overvoltage value, and high output overvoltage protection accuracy. It can flexibly control the specific overvoltage value of the output voltage to meet market demand and is conducive to safe production. It is a highly reliable and cost-effective switching power supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is the overall circuit diagram of the utility model. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0021] like Figure 1As shown, the utility model provides a switching power supply circuit with overvoltage protection, including a main control IC1, a voltage stabilization output unit, an overvoltage protection unit and a power supply unit, the power supply unit including resistors R1, R2, R3, and a capacitor EC3, one end of the capacitor EC3 is connected to the main control IC1, one end of the resistor R1 is connected to one end of R2, one end of the resistor R3 is connected between R1 and R2, and the other end of the resistor R3 is connected between the capacitor EC3 and the main control IC1; when the input end of the switching power supply is connected to the AC voltage, the positive and negative half cycles charge the electrolytic capacitor EC3 through the resistors R1 and R2, when the voltage on EC3 rises to about DC16V, the control IC starts to work, and the 6th foot of the control IC starts to output the PWM signal.

[0022] The voltage-stabilized output unit includes a filter circuit, a feedback loop circuit, and a rectifier filter circuit. The filter circuit includes a rectifier bridge DB1, a switch MOS tube Q1, a capacitor EC1, a transformer TR, a diode D5, and electrolytic capacitors EC4 and EC5. The rectifier bridge DB1 is connected to one end P1 of the transformer TR through capacitor EC1, and the other end P1 of the transformer TR is connected to the drain of the switch MOS tube Q1. The S1 end of the transformer TR is connected to the parallel electrolytic capacitors EC4 and EC5 in sequence through diode D5.

[0023] The feedback loop circuit includes resistors R13, R14, R15, R16, R17, a light-emitting diode PC1, a diode IC2, and a capacitor C6. One end of the resistor R13 is connected to the anode of the light-emitting diode PC1, and the cathode of the light-emitting diode PC1 is connected to the capacitors C6, R15, and R16 in sequence. One end of the resistor R14 is connected between R13 and PC1, and the other end of the resistor R14 is connected between the capacitor C6 and PC1. The cathode of the diode IC2 is connected to the cathode of PC1, and the resistor R17 is connected to the diode IC2.

[0024] The rectifier and filter circuit includes diodes D2 and D3, and a capacitor EC2. The anode of the diode D2 is connected to the overvoltage protection unit, the cathode of the diode D2 is connected to one end of the capacitor EC2, the anode of the diode D3 is connected between D2 and the capacitor EC2, the cathode of the diode D3 is connected to the capacitor EC3, and the capacitor EC3 is connected to the other end of the capacitor EC2.

[0025] When pin 6 of the control IC begins outputting a PWM signal, switching MOSFET Q1 activates. Simultaneously, rectifier bridge DB1 rectifies the current, followed by filtering by capacitor EC1, resulting in a DC voltage across capacitor EC1 that is 1.4 times the input voltage. At this point, transformer TR transfers energy from the primary side to the secondary side (low voltage, high current) through the proportional relationship between windings P1 and S1. The current is then rectified by diode D5 and filtered by electrolytic capacitors EC4 and EC5 before outputting a DC voltage. A feedback loop stabilizes the power supply's output voltage at the set value. The coupled voltage generated by the transformer's VCC winding is rectified by diodes D2 and D3, filtered by capacitors EC2 and EC3, and provides a stable operating voltage for the control IC.

[0026] The overvoltage protection unit includes a transformer VCC and a resistor RV, wherein the transformer VCC is connected to the main control IC1 via the resistor RV;

[0027] When the power supply's input voltage suddenly changes due to uncontrollable factors, causing the output voltage to suddenly increase and exceed the rated value, the output voltage is proportionally coupled to the transformer's VCC winding through the transformer's secondary winding, causing the voltage on the VCC winding to increase even more than the rated value. At this time, the current flowing through resistor RV increases proportionally (when the resistor value remains unchanged, the voltage across the resistor increases proportionally, and the current flowing through the resistor also increases proportionally). When the current value continues to increase to greater than 60uA and remains greater than 60uA for six consecutive cycles, the main control IC immediately shuts off the PWM signal output, and the power supply has no output. When the fault is resolved, the main IC resumes normal operation, the PWM signal output is normal, and the power supply resumes normal operation.

[0028] Although the 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 variations may be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A switching power supply circuit with overvoltage protection, characterized in that: include: Main control IC1, used to output PWM signal; The voltage stabilization output unit is used to stabilize the voltage after obtaining the PWM signal; as well as Overvoltage protection unit, used to detect the voltage of main control IC1 and perform overvoltage protection, The overvoltage protection unit includes a transformer VCC and a resistor RV. The transformer VCC is connected to the main control IC1 through the resistor RV.

2. The switching power supply circuit with overvoltage protection according to claim 1, characterized in that: It also includes a power supply unit for powering the main control IC1, which includes resistors R1, R2, R3, and a capacitor EC3. One end of the capacitor EC3 is connected to the main control IC1, one end of the resistor R1 is connected to one end of R2, one end of the resistor R3 is connected between R1 and R2, and the other end of the resistor R3 is connected between the capacitor EC3 and the main control IC1.

3. The switching power supply circuit with overvoltage protection according to claim 1, characterized in that: The voltage stabilization output unit includes: A filter circuit that obtains PWM signals, filters them, and then outputs a DC voltage. A feedback loop circuit for stabilizing the DC voltage at a set value; and A rectifier and filter circuit is used to rectify and filter DC voltage.

4. The switching power supply circuit with overvoltage protection according to claim 3, characterized in that: The filter circuit includes a rectifier bridge DB1, a switch MOS tube Q1, a capacitor EC1, a transformer TR, a diode D5, and electrolytic capacitors EC4 and EC5. The rectifier bridge DB1 is connected to one end P1 of the transformer TR through the capacitor EC1, and the other end P1 of the transformer TR is connected to the drain of the switch MOS tube Q1. The S1 end of the transformer TR is connected to the parallel electrolytic capacitors EC4 and EC5 in sequence through the diode D5.

5. The switching power supply circuit with overvoltage protection according to claim 4, characterized in that: The feedback loop circuit includes resistors R13, R14, R15, R16, R17, a light-emitting diode PC1, a diode IC2, and a capacitor C6. One end of the resistor R13 is connected to the anode of the light-emitting diode PC1, and the cathode of the light-emitting diode PC1 is connected to the capacitors C6, R15, and R16 in sequence. One end of the resistor R14 is connected between R13 and PC1, and the other end of the resistor R14 is connected between the capacitor C6 and PC1. The cathode of the diode IC2 is connected to the cathode of PC1, and the resistor R17 is connected to the diode IC2.

6. The switching power supply circuit with overvoltage protection according to claim 3, characterized in that: The rectifier and filter circuit includes diodes D2 and D3, and a capacitor EC2. The anode of the diode D2 is connected to the overvoltage protection unit, the cathode of the diode D2 is connected to one end of the capacitor EC2, the anode of the diode D3 is connected between D2 and the capacitor EC2, the cathode of the diode D3 is connected to the capacitor EC3, and the capacitor EC3 is connected to the other end of the capacitor EC2.

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