Switch control circuit based on pin multiplexing, switch power supply system and frequency control method

Abstract

The invention discloses a switch control circuit based on pin multiplexing. The switch control circuit comprises a first pin and a second pin; the switch control circuit is coupled with the first circuit; the first pin is used for outputting a pulse width modulation signal to control the first circuit; the second pin is used for detecting and acquiring detection current flowing through the first circuit in a first time stage, and is used for detecting and acquiring element characteristics of the first circuit in a second time stage; and the switch control circuit controls the pulse width modulation signal according to the detection current and the element characteristic, wherein the element characteristic is used for controlling the system frequency of the first circuit. The invention also discloses a frequency control method and a switch power supply system. Through multiplexing of the same pin, the current change can be monitored and detected, and the frequency of the switch tube can be controlled. In other switching power supply systems applying the invention, the system frequency is controlled by controlling the frequency of the switch tube.

Description

technical field [0001] The present invention relates to the field of electronics, specifically but not limited to a switch control circuit based on multiplexing of pins, a switch power supply system and a frequency control method. Background technique [0002] The flyback voltage conversion circuit includes a transformer, and the circuit is divided into a primary circuit and a secondary circuit for isolation through the primary winding and the secondary winding of the transformer. The switching tube of the primary side circuit transmits the electric energy to the secondary side circuit through the switching action. When the switch tube is turned off to on, the original current in the primary circuit increases from zero, and the primary winding stores energy; when the switch tube is turned on to off, the original current is zero, and the induced current generates , the secondary winding outputs power to the load. Therefore, the turn-on / turn-off frequency of the switch tube ...

AI Technical Summary

Problems solved by technology

[0003] In the prior art, the turn-on / turn-off frequency of the switch tube is usually directly controlled by a fixed-frequency periodic signal, which cannot achieve flexible control of the frequency setting, nor can it monitor the change of the original current, and the structure is often complicated. There are many applications for the pins of the switch control circuit

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