Control circuit applied to power adapter and operation method of control circuit

Abstract

The invention discloses a control circuit and an operating method thereof. The control circuit comprises an auxiliary pin used for receiving auxiliary voltage of an auxiliary winding of a power adapter, a first monitoring unit used for monitoring a first time when the auxiliary voltage starts resonance and outputting a first monitoring signal according to the first time, a second monitoring unit used for monitoring a second time when the auxiliary voltage is up to a preset voltage and outputting a second monitoring signal according to the second time, a delay time controller used for calculating a delay time according to output time difference of the first monitoring signal and the second monitoring signal and outputting a start signal after receiving the second monitoring signal and the delay time is up, and a gate electrode signal generator used for generating a gate electrode control signals to a power switch of the power adapter according to the start signals of the delay time controller. By the control circuit, the power adapter has low power consumption.

Description

technical field [0001] The invention relates to a control circuit applied to a power converter and an operating method thereof, in particular to a control circuit capable of reducing power consumption of the power converter and an operating method thereof. Background technique [0002] Please also refer to figure 1 and figure 2 , figure 1 It is a schematic diagram of a known power converter and a control circuit, figure 2 for figure 1 Schematic diagram of the relevant signals of the power converter and the control circuit. Such as figure 1 As shown, the power converter 10 includes a primary winding PR, an auxiliary winding AUX, a power switch N, a diode D, and a capacitor C1. The power switch M is coupled between the primary winding PR and the ground. The diode D and the capacitor C1 are coupled to the output terminal OUT. The control circuit 100 is coupled to the auxiliary winding AUX and the control end of the power switch M. The control circuit 100 is used to t...

AI Technical Summary

Problems solved by technology

[0003] The known control circuit 100 pre-determines the time point Ton when the auxiliary voltage Vaux reaches the first valley after starting to resonate according to the ideal values ​​of the circuit components of the power converter 10. However, the parameters of the circuit components all have error tolerances, which further affect the auxiliary The resonance frequency of the voltage Vaux, that is, the time point when the auxiliary voltage of different power converters reaches the first valley after resonance may be different

The known control circuit 100 cannot accurately determine the time point Ton when the auxiliary voltage Vaux reaches the first valley after the resonance begins, which in turn causes the known power converter 10 to have relatively large power consumption

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