Hi team,
I am the FAE of SZ AUTO team, supporting Desay SV. Our customer have the FB and Cboot short to GND condition. Now we have tested below condition, they need the theoretical explanations.
Test condition: Vin=12V, Fsw=479.5kHz
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FB short to GND: the Vout is a cyclic square wave, the Vhigh=11.678V for 100ms, Vlow=1V for 50ms. The Vlow time is match the overcurrent retry time 47ms, but the Vhigh time can’t match the overcurrent cycles time. Could you please explain this waveform condition. This condition would not damage the device.
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While FB shorting to GND, short the Cboot pin to GND: the Vout,SW,VCC,Vboot will be lowered to 0V, and then the device will be damaged. We tested after Vin power off, the VCC and Cboot shorted to GND, and sometimes the lower MOS breakdown to GND( SW short to GND). Could you please explain what cause those failure? Especially, we need a theoretical explanation to give customer for the lower MOS’s breakdown.
I am very sorry, I can not attach the waveform now. Our customers are in urgent need of a reply to convince their customer, so hope your reply ASAP.
Best Regards!
Kevin Cheng
