Quasi-resonant Boost soft start circuit

Abstract

The present invention provides a quasi-resonant Boost soft start circuit. The circuit comprises an input voltage interface, a working power supply Vcc, a boost circuit, a quasi-resonant control chip, an output voltage detection feedback circuit, a soft start circuit and an output circuit. The input voltage interface is connected with the boost circuit; the output voltage detection feedback circuit is electrically connected with the boost circuit and the output circuit respectively; the quasi-resonant control chip and the soft start circuit are both connected with the working power supply Vcc; the output voltage detection feedback circuit is provided with a detection feedback end; the soft start circuit is provided with a soft start end; the quasi-resonant control chip is provided with a feedback pin; and the detection feedback end of the output voltage detection feedback circuit, the soft start end of the soft start circuit and the feedback pin of the quasi-resonant control chip are connected together. According to the quasi-resonant Boost soft start circuit provided by the present invention, the soft start circuit is added to a quasi-resonant mode boost PFC, so that the overshoot and inductance saturation problems of an electrolytic capacitor are perfectly solved.

Description

technical field [0001] The invention relates to a quasi-resonant Boost circuit, in particular to a quasi-resonant Boost soft start circuit. Background technique [0002] At present, the working mode of quasi-resonant Boost PFC requires its control to adopt frequency conversion control. When the current of the rectifier diode drops to 0, the main switch is turned on, and when the current reaches a certain value, the main switch is turned off. This working characteristic makes its There is no soft start function like other PWM control ICs (the PWM mode IC achieves the soft start function by controlling the duty cycle), and the current mainstream control quasi-resonant control IC does not have the soft start circuit control function, resulting in the following problems when starting up: 1. Since there is no soft-start circuit, the output voltage overshoots greatly when starting up, resulting in excessive stress of the output electrolytic capacitor, especially under low temperat...

AI Technical Summary

Problems solved by technology

[0003] In order to solve the problem that the quasi-resonant Boost PFC has no soft-start control function and the circuit components are easy to saturate, the present invention proposes a quasi-resonant Boost soft-start circuit, which can be applied to quasi-resonant mode boost PFC and perfectly solves the problem. Overshoot and inductance saturation of electrolytic capacitors

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