Part Number: UCC28780
Dear sir
I have some issues about UCC28780, I'd like to need help.
SPECS: VIN=100VAC, VOUT=20VDC 2.25A , Fsw=500kHz , L=60uH,
When Start up at no load, I confirmed that UCC28780 outputs only about five pulses at 1.5ms interaval.
I can not find above problem and solve written in datasheet shows 1.4.10 System Fault Protections.
But, at 1A Load, it suddenly starts up and it seems work correctly.
And, Load becomes 2Amps and more, it makes some audible noises and I comfirmed below waveform.(Mazenta:Secondary SR gate, blue:lowside Vds, green:PWMH)
Then, I tried to measure main loop current waveform,which is HB node at several times.
However, try to above,some noises are Superimposed on Vds and PWMH waveforms,
it makes unstable operation.
At worst case, it made some semiconductor`s device destroy by EOS.
Thanks.
Best Regards.
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