Valley-switching digital control circuit of switch power source

Abstract

The invention discloses a valley-switching digital control circuit of a switch power source, and belongs to the technical field of switch power source circuit design. The valley-switching digital control circuit comprises a voltage feedback detection module, a current feedback detection module, an arithmetic unit, a valley-switching digital control module, a and gate device and a PWM generating module, wherein the voltage feedback detection module is used for collecting switch power source voltage feedback signals, the current feedback detection module is used for collecting drive switch tube currents, the arithmetic unit is used for obtaining drive switch tube breakover signals according to voltage feedback detection module output signals and current feedback detection module output signals, the valley-switching digital control module is used for obtaining valley-switching signals according to the voltage feedback detection module output signals, the and gate device is used for conducting and operation on the drive switch tube breakover signals and the valley-switching signals, and the PWM generating module is used for generating actual duty ratio signals according to the operation result of the and gate device. By means of the valley-switching digital control circuit, the switch loss is effectively reduced while accurate valley switching is achieved, the valley-switching mode is switched into the real-time breakover mode when the resonant period is abnormal, and the valley-switching digital control circuit is suitable for discontinuous-mode switch power source chips in the PWM mode and PFM mode.

Description

technical field [0001] The invention discloses a valley conduction digital control circuit of a switching power supply, which belongs to the technical field of switching power supply circuit design. Background technique [0002] With the popularity of portable electronic devices, switching power supplies have become the main power supply solutions for such electronic devices. figure 1 A traditional switching power supply chip structure is given. The chip mainly includes: voltage feedback detection module, current feedback detection module, arithmetic unit, PWM generation module. figure 2 A system scheme of a traditional switching power supply chip structure is given. The system mainly includes: rectifier bridge D0, filter capacitor C1, transformer TR1, power chip IC1, switch tube connected to the OUTPUT pin of the power chip IC1, and switch tube connected The CS sampling circuit, the DC output stage connected to the secondary side of the transformer (composed of diode D4 a...

AI Technical Summary

Problems solved by technology

[0006] The technical problem to be solved by the present invention is to address the above-mentioned deficiencies in the background technology and provide a valley conduction drive circuit for switching power supplies, which can solve the valley bottom caused by the large switching loss of the driving switch tube, the constant operating frequency when stable, and the vibration of the resonance period in the resonance area. Inaccurate conduction position, non-operation when resonance is abnormal, and limited design of switching power supply drive circuit

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