A primary side feedback constant current constant voltage control circuit and method

Abstract

The present invention provides a primary side feedback constant current and constant voltage control circuit and method, comprising: a voltage input module; a transformer; a voltage output module; an output voltage feedback module; an energy control module for generating an energy control signal according to a feedback signal; A peak current detection module; a constant current and constant voltage control module that controls a power switch tube according to a feedback signal and an energy control signal; a driving module. The input voltage is output through the transformer and the feedback signal is obtained; the energy control signal is obtained according to the feedback signal, and the sampling current is detected; if the sampling current reaches the peak value, the power switch tube is turned off; if the sampling current does not reach the peak value, the constant current or constant voltage control is performed. The invention adopts the principle of primary side feedback, the circuit structure is simple and the cost is low, which can effectively avoid the deviation or instability of the energy control signal caused by the node leakage or noise burr in the feedback signal being amplified by the error amplifier, and effectively improve the system stability and resistance. Interference ability.

Description

technical field [0001] The invention relates to the field of constant current and constant voltage control, in particular to a primary side feedback constant current and constant voltage control circuit and method. Background technique [0002] In recent years, with the substantial increase in the demand for consumer electronics products and the upgrading of various electronic products, people have higher and higher requirements for power supplies, especially in terms of output current, voltage stability, and system anti-interference capabilities. The requirements are particularly stringent. [0003] The AC / DC (AC / DC) control technology of Primary Switching Regulator (PSR) is a new type of AC / DC control technology developed in the past 10 years. Compared with the traditional constant current and constant voltage control structure of secondary feedback , the biggest advantage of the primary-side feedback constant current and constant voltage control structure is that the two...

AI Technical Summary

Problems solved by technology

[0005] The sampling signal of the existing primary side feedback constant current and constant voltage control circuit is often disturbed by noise, and the parasitic leakage current of the system itself will also have a greater impact on the control signal. Therefore, the output current, voltage stability and system The anti-interference ability still needs to be further improved

Images