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UCC2897A: UCC2897A上电异常

rich wang
Prodigy 10 points

Part Number: UCC2897A

UCC2897A: 基于UCC2897ARGPR设计的反激电路，给电路上电后，首先VREF正常出现5V的电压，然后测量VDD和PVDD（短接在一起）上的电，示波器显示电压一直反复震荡，类似三角波，电压幅值在11V-12.8V之间反复。测量OUT引脚无PWM输出，测量AUX引脚上电压和VDD一样反复震荡，幅值一致。请帮排查原因谢谢！

设计图纸：baihub-poe v2.pdf  图片：3ef7fbabb7eeebc4b31f086ff50fa928.jpg