CN211579583U - Overvoltage protection circuit for outputting accurate voltage - Google Patents
Overvoltage protection circuit for outputting accurate voltage Download PDFInfo
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- CN211579583U CN211579583U CN202020604998.7U CN202020604998U CN211579583U CN 211579583 U CN211579583 U CN 211579583U CN 202020604998 U CN202020604998 U CN 202020604998U CN 211579583 U CN211579583 U CN 211579583U
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Abstract
The utility model relates to an output overvoltage crowbar of accurate voltage, including input line, output line, filter circuit, starting circuit, sampling circuit, feedback circuit, bleeder circuit, power chip G5138P, transformer, output rectification filter circuit. The input line filters the current through a filter circuit and supplies power to the main winding T1A; the starting circuit provides starting voltage and working voltage for the power supply chip G5138P, and square waves are output at pin 5 and pin 6 of the power supply chip G5138P. The capacitor C5 of the sampling circuit converts the current signal flowing through the transformer into a voltage signal for sampling of the power supply chip G5138P, the feedback circuit provides feedback voltage for the power supply chip G5138P, the output rectifying and filtering circuit is connected with the secondary winding T1C of the transformer T1, and power is supplied to the outside after rectification and filtering. The power chip G5138P detects the voltage divided by the voltage divider circuit through the pin 2 to detect the voltage of the auxiliary winding T1B, so as to determine the output voltage value, and determine whether to enter the OVP overvoltage protection mode, so as to ensure the safety of the rear-stage electric product.
Description
Technical Field
The utility model relates to a circuit field, more specifically say, relate to an overvoltage crowbar of output accurate voltage.
Background
In real life, a power supply from a power plant is an alternating current unsafe voltage, and most electronic products need safe low-voltage direct current voltage power supply.
The OVP overvoltage protection of the existing product in the current market has overlarge output voltage deviation due to the detection mechanism difference, and the safety of rear-end electric equipment cannot be ensured.
At present, a power supply is generally adopted to reduce and rectify alternating voltage and then supply power to an electronic product, a semiconductor chip in the electronic product is very sensitive to the voltage, the voltage which is abnormal and exceeds the specification is light, the electronic product is damaged, and serious heat is generated, so that safety accidents such as smoking, ignition and the like are caused; therefore, the power supply for supplying power to the electronic product needs to be improved to ensure that the output voltage does not exceed the highest voltage that the electronic product can bear when an abnormality occurs.
SUMMERY OF THE UTILITY MODEL
The to-be-solved technical problem of the utility model lies in providing an overvoltage crowbar of output accurate voltage.
The utility model provides a technical scheme that its technical problem adopted is: an overvoltage protection circuit for outputting accurate voltage is constructed, and the overvoltage protection circuit comprises an input line, an output line, a filter circuit, a starting circuit, a sampling circuit, a feedback circuit, a voltage division circuit, a power chip G5138P, a transformer and an output rectifying filter circuit;
the transformer comprises a primary winding and a secondary winding T1C, wherein the primary winding comprises a main winding T1A and an auxiliary winding T1B;
the input line is connected to the main winding T1A through the filter circuit, and the current is filtered to supply power to the main winding T1A;
the starting circuit is connected with the pin 1 of the power chip G5138P, the input end of the main winding T1A, the input end of the auxiliary winding T1B and the output end of the auxiliary winding T1, provides starting voltage and working voltage for the power chip G5138P, and outputs square waves at the pin 5 and the pin 6 of the power chip G5138P;
the pin 5 and the pin 6 of the power chip G5138P are connected with the output end of the main winding T1A to control the current flowing through the main winding T1A;
the sampling circuit comprises a capacitor C5 connected among the pin 5, the pin 6 and the pin 4, and converts a current signal flowing through the transformer into a voltage signal for sampling the power supply chip G5138P;
the feedback circuit is connected with the input end of the auxiliary winding T1B and the sampling circuit, pin 3 of the power chip G5138P is connected with the feedback circuit, and a feedback voltage is supplied to the power chip G5138P;
the output rectifying and filtering circuit is connected with a secondary winding T1C of the transformer T1, and supplies power to the outside after rectification and filtering.
Preferably, the overvoltage protection circuit further comprises a fuse F1 and a rectifier bridge stack BD1, an L line of the input line is connected to a first input terminal of the rectifier bridge stack BD1 through the fuse F1, an N line of the input line is connected to a second input terminal of the rectifier bridge stack BD1, and two output terminals of the rectifier bridge stack BD1 are connected to the filter circuit.
Preferably, the filter circuit includes an electrolytic capacitor EC1, an electrolytic capacitor EC2, and a filter inductor LF1, and two ends of the electrolytic capacitor EC1 are respectively connected to the same ends of two windings of the filter inductor LF1, and then are respectively connected to two output ends of the rectifier bridge stack BD 1;
after the two ends of the electrolytic capacitor EC2 are respectively connected with the other ends of the two windings of the filter inductor LF1, the anode of the electrolytic capacitor EC2 is connected with the input end of the main winding T1A.
Preferably, the overvoltage protection circuit further comprises a spike absorption loop, the spike absorption loop comprises a diode D1, a resistor R3, a resistor R4, a resistor R5, resistors R6 and R7, and a capacitor C1, the resistor R3, the resistor R4, the resistor R5 and the capacitor C1 are connected in parallel, and the resistor R6 and the resistor R7 are connected in parallel;
the anode of the diode D1 is connected to the pin 5 and pin 6 of the power chip G5138P and the output end of the primary winding T1A of the transformer T1, the cathode of the diode D1 is connected to one end of the resistor R6 and one end of the resistor R7 which are connected in parallel, the other end of the resistor R6 and the other end of the resistor R7 which are connected in parallel are connected to one end of the resistor R3, the resistor R4, the resistor R5 and the capacitor C1 which are connected in parallel, and the other ends of the resistor R3, the resistor R4, the resistor R5 and the capacitor C1 which are connected in parallel are connected to the positive end of the electrolytic capacitor EC2 and the input end of the primary winding T1A.
Preferably, the starting circuit includes a resistor R1, a resistor R2, a resistor R8, a diode D2, a capacitor EC3 and a capacitor C2, one end of the resistor R1 and the resistor R2 after being connected in series is connected to the input end of the main winding T1A, one end of the resistor R8 is connected to the input end of the auxiliary winding T1B, the other end of the resistor R8 is connected to the positive electrode of the diode D2, after the capacitor EC3 and the capacitor C2 are connected in parallel, the pin 1 of the power chip G51 5138P is connected to the positive electrode of the capacitor EC3 and the capacitor C2 after being connected in parallel, the negative electrode of the diode D2 and the resistor R2, and the negative electrode of the capacitor EC3 and the capacitor C2 after being connected in parallel is connected to the output end of the auxiliary winding T1B.
Preferably, the feedback circuit includes a resistor R9, a resistor R10, a resistor R11 and a capacitor C3 which are connected in parallel, one end of the resistor R9 and one end of the resistor R10 which are connected in parallel are connected with the input end of the auxiliary winding T1B, the other end of the resistor R11 and the other end of the resistor R3 which are connected in parallel are connected with each other, the resistor R11 and the capacitor C3 which are connected in parallel are connected with the sampling circuit, and the pin 3 of the power chip G5138P is connected between the resistor R9 and the resistor R10 which are connected in parallel and the resistor R11 and the capacitor C3 which are connected in parallel.
Preferably, the voltage dividing circuit comprises a resistor R18 and a resistor R16 which are connected in series, the pin 2 of the power chip G5138P is connected between the resistor R18 and the resistor R16, the resistor R18 is connected with the input end of the auxiliary winding T1B, and the resistor R16 is connected with the feedback circuit and the sampling circuit.
Preferably, the sampling circuit further includes a resistor R12, a resistor R13, and a resistor R14 connected in parallel, one end of the resistor R12, the resistor R13, and the resistor R14 connected in parallel is connected to the pin 4 and the capacitor C5, and the other end is connected to the feedback circuit and grounded.
Preferably, the output rectifying and filtering circuit comprises a diode D3, an electrolytic capacitor EC4 and an electrolytic capacitor EC5, wherein the anode of the diode D3 is connected with the input end of the secondary winding T1C, the anodes of the electrolytic capacitor EC4 and the electrolytic capacitor EC5 are respectively connected with the cathode of the diode D3, and the cathodes of the electrolytic capacitor EC4 and the electrolytic capacitor EC5 are respectively connected with the output end of the secondary winding T1C.
Preferably, the overvoltage protection circuit further comprises a secondary protection circuit, the secondary protection circuit comprises a resistor R15 and a capacitor C6 which are connected in series, the resistor R15 and the capacitor C6 are connected in series and then connected in parallel with the diode D3, the anodes of the resistor R15 and the diode D3 are connected with the input end of the secondary winding T1C, and the capacitor C6 is connected with the cathode of the diode D3;
the overvoltage protection circuit also comprises a safety capacitor CY1 connected between the positive electrode of the electrolytic capacitor EC2 and the negative electrode of the electrolytic capacitor EC 4.
Implement the utility model discloses an output accurate voltage's overvoltage crowbar has following beneficial effect: after the power supply normally works, the power chip G5138P detects the voltage distributed by the voltage division circuit through the pin 2 to detect the voltage of the auxiliary winding T1B so as to determine the output voltage value, when the detected voltage exceeds the reference voltage in the power chip G5138P, the power chip G5138P judges that the output voltage exceeds the standard, quickly enters an OVP overvoltage protection mode, and stops working of the circuit so as to ensure the safety of a rear-stage electric product; and when the abnormality is relieved, the power supply recovers to work normally.
Drawings
The invention will be further explained with reference to the drawings and examples, wherein:
fig. 1 is a schematic circuit schematic structure diagram of an overvoltage protection circuit for outputting accurate voltage in an embodiment of the present invention.
Detailed Description
In order to clearly understand the technical features, objects, and effects of the present invention, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
As shown in fig. 1, the overvoltage protection circuit for outputting accurate voltage in a preferred embodiment of the present invention includes an input line, an output line, a filter circuit, a start circuit, a sampling circuit, a feedback circuit, a voltage dividing circuit, a power chip G5138P, a transformer, and an output rectifying filter circuit.
The transformer comprises a primary winding and a secondary winding T1C, wherein the primary winding comprises a main winding T1A and an auxiliary winding T1B. The input line is connected to the main winding T1A via a filter circuit to filter the current and supply power to the main winding T1A.
The starting circuit is connected with the pin 1 of the power chip G5138P, the input end of the main winding T1A, the input end of the auxiliary winding T1B and the output end of the auxiliary winding T1, provides starting voltage and working voltage for the power chip G5138P, and outputs square waves at the pin 5 and the pin 6 of the power chip G5138P.
The pin 5 and the pin 6 of the power chip G5138P are connected to the output end of the main winding T1A to control the current flowing through the main winding T1A.
The sampling circuit comprises a capacitor C5 connected among pin 5, pin 6 and pin 4, and converts the current signal flowing through the transformer into a voltage signal for sampling by the power supply chip G5138P.
The feedback circuit is connected with the input end of the auxiliary winding T1B and the sampling circuit, pin 3 of the power chip G5138P is connected with the feedback circuit, and the feedback voltage is supplied to the power chip G5138P.
The output rectifying and filtering circuit is connected with a secondary winding T1C of the transformer T1, and supplies power to the outside after rectification and filtering.
After alternating current is rectified and filtered, a controllable square wave is generated by a digital power supply chip G5138P, the square wave reduces higher voltage to safety voltage required by people through a transformer, the square wave is rectified by a secondary output rectifying and filtering circuit and filtered into direct current voltage through an output electrolytic capacitor, the output voltage is connected to an output line to supply power to external electronic equipment, the power supply chip G5138P is provided with a multifunctional pin which can detect the voltage of a feedback winding to calculate the output voltage, when the voltage detected by the pin reaches a set value, a secondary protection circuit quickly enters protection and turns off the output, and the output protection voltage can be set randomly according to requirements.
After the power supply normally works, the power chip G5138P detects the voltage distributed by the voltage division circuit through the pin 2 to detect the voltage of the auxiliary winding T1B so as to determine the output voltage value, when the detected voltage exceeds the reference voltage in the power chip G5138P, the power chip G5138P judges that the output voltage exceeds the standard, quickly enters an OVP overvoltage protection mode, and stops working of the circuit so as to ensure the safety of a rear-stage electric product; and when the abnormality is relieved, the power supply recovers to work normally.
The power supply capable of realizing accurate output voltage protection based on the digital integrated power supply chip G5138P can automatically set OVP protection points according to product requirements so as to meet the requirements of different products. Compared with the existing products, the cost of the used materials is not increased basically; because the power chip G5138P is a digital chip, the consistency of mass production is good, and the platform compatibility is strong.
The overvoltage protection circuit further comprises a fuse F1 and a rectifier bridge stack BD1, an L line of an input line is connected with a first input end of the rectifier bridge stack BD1 through the fuse F1, an N line of the input line is connected with a second input end of the rectifier bridge stack BD1, and two output ends of the rectifier bridge stack BD1 are connected to the filter circuit.
The filter circuit comprises an electrolytic capacitor EC1, an electrolytic capacitor EC2 and a filter inductor LF1, wherein two ends of the electrolytic capacitor EC1 are respectively connected with the same ends of two windings of the filter inductor LF1 and then are respectively connected with two output ends of the rectifier bridge stack BD 1.
After the two ends of the electrolytic capacitor EC2 are respectively connected with the other ends of the two windings of the filter inductor LF1, the anode of the electrolytic capacitor EC2 is connected with the input end of the main winding T1A, and the filtered power is supplied to the main winding T1A of the transformer.
The overvoltage protection circuit also comprises a peak absorption loop which can ensure the power supply chip G5138P to work safely. The peak absorption loop comprises a diode D1, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7 and a capacitor C1, wherein the resistor R3, the resistor R4, the resistor R5 and the capacitor C1 are connected in parallel, and the resistor R6 and the resistor R7 are connected in parallel.
The anode of the diode D1 is connected to the pin 5 and pin 6 of the power chip G5138P and the output end of the primary winding T1A of the transformer T1, the cathode of the diode D1 is connected to one end of the parallel resistor R6 and resistor R7, the other end of the parallel resistor R6 and resistor R7 is connected to one end of the parallel resistor R3, resistor R4, resistor R5 and capacitor C1, and the other end of the parallel resistor R3, resistor R4, resistor R5 and capacitor C1 is connected to the positive end of the electrolytic capacitor EC2 and the input end of the primary winding T1A.
The starting circuit comprises a resistor R1, a resistor R2, a resistor R8, a diode D2, a capacitor EC3 and a capacitor C2, wherein one end of the resistor R1 and the resistor R2 after being connected in series is connected with the input end of the main winding T1A, one end of the resistor R8 is connected with the input end of the auxiliary winding T1B, the other end of the resistor R8 is connected with the anode of the diode D2, after the capacitor EC3 and the capacitor C2 are connected in parallel, a pin 1 of a power chip G5138P is connected with the anode end of the capacitor EC3 and the anode end of the capacitor C2 after being connected in parallel, the cathode end of the diode D2 and the resistor R2, and the cathode end of the capacitor EC3 and the capacitor C2 after being connected in parallel.
The resistor R1 and the resistor R2 provide starting voltage for the power chip G5138P when the power chip G5138P is electrified, after the power chip G5138P starts to work, a controllable square wave can be output at the pin 5 and the pin 6 of the power chip G5138P, and the pin 5 and the pin 6 of the power chip G5138P are connected with the main winding T1A of the transformer to control the current flowing through the main winding T1A of the transformer. The auxiliary winding T1B of the transformer is connected with a diode D2 through a resistor R8, and provides voltage for the normal operation of a power chip G5138P through a diode D2, an electrolytic capacitor EC3 and a capacitor C2.
The feedback circuit comprises a resistor R9, a resistor R10, a resistor R11 and a capacitor C3 which are connected in parallel, one end of the resistor R9 and one end of the resistor R10 which are connected in parallel are connected with the input end of the auxiliary winding T1B, the other end of the resistor R11 and the capacitor C3 which are connected in parallel are connected, the resistor R11 and the capacitor C3 which are connected in parallel are connected with the sampling circuit, the pin 3 of the power supply chip G51 5138P is connected between the resistor R9 and the resistor R10 which are connected in parallel, the resistor R11 and the capacitor C3 which are connected in parallel, and the feedback circuit provides feedback voltage for the power supply chip G5138P.
The voltage division circuit comprises a resistor R18 and a resistor R16 which are connected in series, a pin 2 of a power chip G5138P is connected between the resistor R18 and the resistor R16, the resistor R18 is connected with the input end of an auxiliary winding T1B, and the resistor R16 is connected with the feedback circuit and the sampling circuit. The power chip G5138P sets the line voltage drop compensation of the output when the power chip is fully loaded according to the parallel connection value of the resistor R18 and the resistor R16, and determines the output voltage value by detecting the voltage of the pin 2 after normal operation.
After the power supply normally works, the power supply chip G5138P detects the voltage divided by the resistor R18 and the resistor R16 through the 2 nd pin to detect the voltage of the auxiliary winding T1B so as to determine the output voltage value, when the detected voltage exceeds the reference voltage in the power supply chip G5138P, the power supply chip G5138P judges that the output voltage exceeds the standard, quickly enters an OVP protection mode, and stops working circuits so as to ensure the safety of rear-stage electric products; and when the abnormality is relieved, the power supply recovers to work normally.
The sampling circuit further comprises a resistor R12, a resistor R13 and a resistor R14 which are connected in parallel, one end of the resistor R12, one end of the resistor R13 and one end of the resistor R14 which are connected in parallel are connected with the pin 4 and the capacitor C5, the other end of the resistor R14 is connected with the feedback circuit and grounded, and current signals flowing through the transformer are converted into voltage signals which are sent to the power chip G5138P for sampling.
The power chip G5138P adjusts the frequency and time of square wave output by pin pins 5 and 6 of the power chip G5138P according to the signals provided by pin pins 3 and 4, so as to ensure that the output voltage and current are required.
The output rectifying and filtering circuit comprises a diode D3, an electrolytic capacitor EC4 and an electrolytic capacitor EC5, wherein the anode of the diode D3 is connected with the input end of the secondary winding T1C, the anodes of the electrolytic capacitor EC4 and the electrolytic capacitor EC5 are respectively connected with the cathode of the diode D3, and the cathodes of the electrolytic capacitor EC4 and the electrolytic capacitor EC5 are respectively connected with the output end of the secondary winding T1C. The output rectifying filter circuit is respectively used as the positive pole and the negative pole of the power supply and is respectively connected with the positive pole and the negative pole of the output line.
The overvoltage protection circuit further comprises a secondary protection circuit, the secondary protection circuit comprises a resistor R15 and a capacitor C6 which are connected in series, the resistor R15 and the capacitor C6 are connected in series and then connected in parallel with a diode D3 to serve as a protection circuit of a diode D3, the anodes of the resistor R15 and the diode D3 are connected with the input end of the secondary winding T1C, and the capacitor C6 is connected with the cathode of the diode D3.
The resistor R17 is connected in parallel with the positive and negative ends of the electrolytic capacitor EC5 and is used as a dummy load of a power supply. The overvoltage protection circuit also comprises a safety capacitor CY1 connected between the anode of the electrolytic capacitor EC2 and the cathode of the electrolytic capacitor EC4, and the safety capacitor CY1 serves as a low-resistance path of switching noise and prevents power supply noise from spreading outwards.
It is to be understood that the above-described respective technical features may be used in any combination without limitation.
The above only is the embodiment of the present invention, not limiting the patent scope of the present invention, all the equivalent structures or equivalent processes that are used in the specification and the attached drawings or directly or indirectly applied to other related technical fields are included in the patent protection scope of the present invention.
Claims (10)
1. An overvoltage protection circuit for outputting accurate voltage is characterized by comprising an input line, an output line, a filter circuit, a starting circuit, a sampling circuit, a feedback circuit, a voltage division circuit, a power chip G5138P, a transformer and an output rectifying filter circuit;
the transformer comprises a primary winding and a secondary winding T1C, wherein the primary winding comprises a main winding T1A and an auxiliary winding T1B;
the input line is connected to the main winding T1A through the filter circuit, and the current is filtered to supply power to the main winding T1A;
the starting circuit is connected with the pin 1 of the power chip G5138P, the input end of the main winding T1A, the input end of the auxiliary winding T1B and the output end of the auxiliary winding T1, provides starting voltage and working voltage for the power chip G5138P, and outputs square waves at the pin 5 and the pin 6 of the power chip G5138P;
the pin 5 and the pin 6 of the power chip G5138P are connected with the output end of the main winding T1A to control the current flowing through the main winding T1A;
the sampling circuit comprises a capacitor C5 connected among the pin 5, the pin 6 and the pin 4, and converts a current signal flowing through the transformer into a voltage signal for sampling the power supply chip G5138P;
the feedback circuit is connected with the input end of the auxiliary winding T1B and the sampling circuit, pin 3 of the power chip G5138P is connected with the feedback circuit, and a feedback voltage is supplied to the power chip G5138P;
pin 2 of the power chip G5138P is connected to the voltage divider circuit, one end of the voltage divider circuit is connected to the input end of the auxiliary winding T1B, and the other end of the voltage divider circuit is connected to the positions between the feedback circuit and the sampling circuit;
the output rectifying and filtering circuit is connected with a secondary winding T1C of the transformer T1, and supplies power to the outside after rectification and filtering.
2. The over-voltage protection circuit outputting precise voltage according to claim 1, further comprising a fuse F1 and a rectifier bridge stack BD1, wherein L lines of the input lines are connected to a first input terminal of the rectifier bridge stack BD1 via the fuse F1, N lines of the input lines are connected to a second input terminal of the rectifier bridge stack BD1, and two output terminals of the rectifier bridge stack BD1 are connected to the filter circuit.
3. The overvoltage protection circuit for outputting precise voltage according to claim 2, wherein the filter circuit comprises an electrolytic capacitor EC1, an electrolytic capacitor EC2 and a filter inductor LF1, two ends of the electrolytic capacitor EC1 are respectively connected to the same ends of two windings of the filter inductor LF1, and then are respectively connected to two output ends of the rectifier bridge stack BD 1;
after the two ends of the electrolytic capacitor EC2 are respectively connected with the other ends of the two windings of the filter inductor LF1, the anode of the electrolytic capacitor EC2 is connected with the input end of the main winding T1A.
4. The overvoltage protection circuit for outputting precise voltage according to claim 3, further comprising a spike absorption loop, wherein the spike absorption loop comprises a diode D1, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7 and a capacitor C1, the resistor R3, the resistor R4, the resistor R5 and the capacitor C1 are connected in parallel, and the resistor R6 and the resistor R7 are connected in parallel;
the anode of the diode D1 is connected to the pin 5 and pin 6 of the power chip G5138P and the output end of the primary winding T1A of the transformer T1, the cathode of the diode D1 is connected to one end of the resistor R6 and one end of the resistor R7 which are connected in parallel, the other end of the resistor R6 and the other end of the resistor R7 which are connected in parallel are connected to one end of the resistor R3, the resistor R4, the resistor R5 and the capacitor C1 which are connected in parallel, and the other ends of the resistor R3, the resistor R4, the resistor R5 and the capacitor C1 which are connected in parallel are connected to the positive end of the electrolytic capacitor EC2 and the input end of the primary winding T1A.
5. The overvoltage protection circuit for outputting precise voltage according to claim 1, wherein the starting circuit comprises a resistor R1, a resistor R2, a resistor R8, a diode D2, a capacitor EC3 and a capacitor C2, one end of the resistor R1 and the resistor R2 is connected in series with the input end of the main winding T1A, one end of the resistor R8 is connected with the input end of the auxiliary winding T1B, the other end of the resistor R8 is connected with the anode of the diode D2, after the capacitor EC3 and the capacitor C2 are connected in parallel, the pin 1 of the power chip G51 5138P is connected with the anode of the capacitor EC3 and the capacitor C2 connected in parallel, the cathode of the diode D2 and the resistor R2, and the cathode of the capacitor EC3 and the cathode of the capacitor C2 connected in parallel with the output end of the auxiliary winding T1B.
6. The overvoltage protection circuit for outputting precise voltage according to claim 1, wherein the feedback circuit comprises a resistor R9, a resistor R10, a resistor R11 and a capacitor C3 which are connected in parallel, one end of the resistor R9 and the resistor R10 which are connected in parallel are connected with the input end of the auxiliary winding T1B, the other end of the resistor R11 and the capacitor C3 which are connected in parallel are connected with the sampling circuit, the resistor R11 and the capacitor C3 which are connected in parallel are connected with the sampling circuit, and the pin 3 of the power chip G5138P is connected between the resistor R9 and the resistor R10 which are connected in parallel and the resistor R11 and the capacitor C3 which are connected in parallel.
7. The overvoltage protection circuit for outputting precise voltage according to claim 1, wherein the voltage dividing circuit comprises a resistor R18 and a resistor R16 connected in series, pin 2 of the power chip G5138P is connected with the resistor R18 and the resistor R16, the resistor R18 is connected with the input end of the auxiliary winding T1B, and the resistor R16 is connected with the feedback circuit and the sampling circuit at a position.
8. The overvoltage protection circuit for outputting precise voltage according to claim 1, wherein the sampling circuit further comprises a resistor R12, a resistor R13 and a resistor R14 connected in parallel, one end of the resistor R12, the resistor R13 and the resistor R14 connected in parallel is connected with the pin 4 and the capacitor C5, and the other end is connected with the feedback circuit and grounded.
9. The overvoltage protection circuit for outputting precise voltage according to any one of claims 1 to 8, wherein the output rectifying and filtering circuit comprises a diode D3, an electrolytic capacitor EC4 and an electrolytic capacitor EC5, the anode of the diode D3 is connected with the input end of the secondary winding T1C, the anodes of the electrolytic capacitor EC4 and the electrolytic capacitor EC5 are respectively connected with the cathode of the diode D3, and the cathodes of the electrolytic capacitor EC4 and the electrolytic capacitor EC5 are respectively connected with the output end of the secondary winding T1C.
10. The overvoltage protection circuit outputting precise voltage according to claim 9, further comprising a secondary protection circuit, wherein the secondary protection circuit comprises a resistor R15 and a capacitor C6 connected in series, the resistor R15 and the capacitor C6 are connected in series and then connected in parallel with the diode D3, the positive poles of the resistor R15 and the diode D3 are connected with the input end of the secondary winding T1C, and the negative pole of the diode D3 is connected with the capacitor C6;
the overvoltage protection circuit also comprises a safety capacitor CY1 connected between the positive electrode of the electrolytic capacitor EC2 and the negative electrode of the electrolytic capacitor EC 4.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202020604998.7U CN211579583U (en) | 2020-04-21 | 2020-04-21 | Overvoltage protection circuit for outputting accurate voltage |
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| CN202020604998.7U CN211579583U (en) | 2020-04-21 | 2020-04-21 | Overvoltage protection circuit for outputting accurate voltage |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113922648A (en) * | 2021-09-22 | 2022-01-11 | 上海军陶科技股份有限公司 | Output overvoltage protection circuit of isolated switching power supply |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113922648A (en) * | 2021-09-22 | 2022-01-11 | 上海军陶科技股份有限公司 | Output overvoltage protection circuit of isolated switching power supply |
| CN113922648B (en) * | 2021-09-22 | 2022-05-17 | 上海军陶科技股份有限公司 | Output overvoltage protection circuit of isolated switching power supply |
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