A zero-crossing detection circuit for inductor current in a power switch chip

Abstract

A zero-crossing detection circuit of an inductor current in a power switch chip, comprising: a power switch tube, the drain of which is connected to the detected inductance, and its source is grounded through a sampling resistor; a first comparator, a positive phase input terminal connected to the power switch The source of the tube is connected, the inverting input terminal is connected to the first comparison voltage, and its output terminal is used to output the shutdown signal; the R input terminal of the RS flip-flop is connected to the output terminal of the first comparator for receiving the shutdown signal. signal, its output end is connected to the gate of the power switch tube through the driver stage; the output end of the zero-crossing comparator is connected to the S input end of the RS flip-flop to generate and output the start signal; the zero-crossing detection module is used for The zero-crossing detection of the inductor current on the secondary side is realized, and then the turn-off of the power switch tube is controlled. By utilizing the zero-crossing detection circuit of the inductance current in the power switch chip of the present invention, the technical solution of the integrable zero-crossing detection is realized.

Description

technical field [0001] The invention relates to a zero-crossing detection circuit of an inductance current in a power switch chip. Background technique [0002] The zero-crossing detection circuit of the inductor current in the existing power switch chip is as follows: figure 1 As shown, in the power switch chip, it is often used in discontinuous or critical operating mode applications, by detecting the peak current on the primary side inductance of the transformer 7 to control the shutdown of the power switch tube 4, and detecting the overcurrent on the secondary side inductance of the transformer 7 The zero control power switch tube 4 is turned on. like figure 1 As shown, during the conduction period of the power switch tube 4, the primary inductor current of the transformer 7 continues to increase, and the primary inductor current is sampled by the sampling resistor 5 (RCS) to generate a VCS signal, which is compared with the first reference voltage VREF by the comparat...

AI Technical Summary

Problems solved by technology

On the one hand, peripheral devices require device cost; on the other hand, it also increases the area of ​​the PCB board, which has a great impact on many applications that have strict requirements on the area (small volume LED lighting equipment)

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