Sample-taking feedback circuit of switch electric power output electric voltage

Abstract

The invention proposes a sampling feedback circuit of the output voltage of the switching power supply used in the switching power supply circuit, which is composed of separate components, has simple structure, strong system stability and low cost. The invention includes a voltage sampling circuit, an error amplification circuit, and an isolation conversion circuit. The output voltage Vo of the switching power supply is input through the voltage signal input terminal of the voltage sampling circuit, and the sampling signal is obtained by dividing the voltage, and the voltage input signal Vo is simultaneously used as the error amplification circuit. Power supply, the sampling signal is input through the sampling signal input terminal of the error amplifier circuit, converted into a current-type error signal and output to the error current signal input terminal of the isolation conversion circuit, and electrically isolated to obtain the feedback output signal Vfb.

Description

technical field [0001] The invention relates to a voltage signal feedback circuit, in particular to a sampling feedback circuit for the output voltage of a switching power supply. Background technique [0002] Power supply is an indispensable part of various electronic equipment. Switching power supply occupies an important position in power supply technology. Most modern power supplies use this technology. Its advantages are reduced raw material consumption, miniaturization, fast dynamic response of the system, high efficiency, and effective Suppress noise pollution. [0003] Most of today's switching power supplies use PWM pulse width modulation technology, which first performs basic rectification and filtering on the mains to convert AC signals into DC. Then through the high-frequency switching action of the switching device, the DC voltage is converted into a high-frequency AC voltage, and an isolated high-frequency AC voltage is induced on the output side of the power ...

AI Technical Summary

Problems solved by technology

[0014] (2) At present, a small number of power supplies use operational amplifiers for error amplification feedback, but this method still cannot achieve electrical isolation, and has high requirements for operational amplifiers

[0015] (3) Although the circuit using the auxiliary winding of the transformer for voltage sampling and feedback can achieve electrical isolation, when the load of the power supply changes greatly, the voltage stabilization effect is very poor

Therefore, it is necessary to add an auxiliary winding to provide the working voltage of the optocoupler and t1431, which increases the complexity of the transformer winding, and in some applications will interfere with the winding of the main output circuit

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