A primary-side regulation (PSR) constant current (CC) output and constant voltage (CV) output AC–DC converter is proposed and an adaptive high-precision closed-loop constant current control scheme is put forward in this paper. In the CC mode, the converter adopts the closed-loop control strategy to realize that the switching period adaptively converges to twice the demagnetization time, which realizes the CC output. In addition, exactly detecting the demagnetization time is a prerequisite for obtaining a high-precision output current. Therefore, a demagnetization time detection circuit is designed to provide accurate and reliable demagnetization information. The control IC was fabricated with the Nuvoton 0.5um BCD process, and a 5 V/2 A prototype circuit was implemented to verify its performance. Experimental results show that the CC deviation is within ± 1.4%, which is lower than the target value of ± 2.0%. Under different loads and AC inputs, the conversion efficiency in the CC mode varies between 76.3% and 80.7%.

本文提出了一种初级侧调节(PSR)恒流(CC)输出和恒压(CV)输出的AC-DC转换器，并提出了一种自适应高精度闭环恒流控制方案。CC模式下，转换器采用闭环控制策略，实现开关周期自适应收敛到两倍退磁时间，实现CC输出。此外，准确检测退磁时间是获得高精度输出电流的前提。为此，设计了退磁时间检测电路，提供准确可靠的退磁信息。控制IC采用Nuvoton 0.5um BCD工艺制造，并实现了5 V/2 A原型电路以验证其性能。实验结果表明CC偏差在±1.4%以内，低于目标值±2.0%。在不同的负载和交流输入下，CC 模式下的转换效率在 76.3% 和 80.7% 之间变化。