Power circuit

Abstract

The present invention provides a power supply circuit, which includes a first rectifying and filtering circuit, an isolated high-frequency transformer, a second rectifying and filtering circuit, a transistor, a first feedback circuit, a second feedback circuit, and a third feedback circuit and a pulse width modulation controller. Under the control of the transistor, the external AC voltage outputs a DC voltage after passing through the first rectifying and filtering circuit, the isolated high-frequency transformer and the second rectifying and filtering circuit. The input voltage of the primary winding is fed back to the voltage sampling terminal of the pulse width modulation controller through the first feedback circuit, and the induced voltage of the first auxiliary winding is fed back to the pulse width modulation controller through the second feedback circuit Voltage sampling terminal. The induced voltage of the second auxiliary winding is fed back to the overvoltage protection terminal of the pulse width modulation controller through the third feedback circuit, and the pulse width modulation controller controls the working state of the power supply circuit according to the input feedback signal.

Description

technical field [0001] The present invention relates to a power supply circuit. Background technique [0002] see figure 1 , which is a schematic diagram of the circuit structure of a prior art power supply circuit. The power supply circuit 10 includes a first rectification filter circuit 11 , a protection circuit 13 , an isolation high frequency transformer 14 , a second rectification filter circuit 15 , a transistor 17 , a feedback circuit 18 and a pulse width modulation controller 19 . The first rectifier filter circuit 11 includes two input terminals 111 and 112 , a full-bridge rectifier circuit 113 , a filter capacitor 114 and an output terminal 115 , and the isolation high frequency transformer 14 includes a primary winding 141 and a secondary winding 142 , the second rectifying filter circuit 15 includes two input ends 151 , 152 and an output end 150 , and the PWM controller 19 includes a control end 191 and a voltage sampling end 192 . [0003] The two input ends...

AI Technical Summary

Problems solved by technology

[0007] In order to solve the problem that the overcurrent point of the output end of the power supply circuit varies greatly in the prior art, the present invention provides a power supply circuit that stabilizes the overcurrent point of the output end

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