UCC256301搭配PFC:UCC28180,上电经常不正常,后来改了环路上供给光耦的电流,空载电压为45V,稍微带100mA电流就没有输出,改了一下TL431的反馈RC数值后,启动又不正常了,感觉像是反复自动,是什么原因呢?波形如附件,CH1是低管驱动脚,CH2是软起动脚,CH3是FB脚。
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Hi
首先PFC是否正常输出?
如果是UCC256301输出不正常,也就是完全带不动负载,是吗? 确认一下变压器和保护电路?
PFC工作正常,UCC256301工作不正常,输出跳变,也带不起载。变压器参数如:励磁电感270uH,谐振电感57uH,谐振电容47nF。感觉在启动的过程中都不怎么对劲,请见附件下管驱动波形及VCR脚的波形。