A Constant Current Regulation for Primary-side Controlled Flyback Converter

Abstract

This article proposes a constant current regulation design for pri­mary-side controlled flyback converter. The regulation circuit consists of two parts: an OSC circuit and an adaptive primary side peak current thresh­old compensation circuit. The OSC circuit generates a switching cycle sig­nal with a fixed ratio to the demagnetization time, and the adaptive primary side peak current threshold compensation circuit. To verify the feasibility and accuracy of the proposed constant current regulation design, the de­signed chip was fabricated and tested. Under 12V/1.9A configuration, the test results showed that the line regulation and load regulation of the output current can achieve within ±1.7% and ±0.15%, respectively.