Tool/software:
Hi,
Vin=36-75V
Vout1=12V
Iout1=1A
Vout2=12V
Iout2=3A
Fsw=100KHz
We are using the LM5020 as a flyback converter. The MOSFET seems to be trying to turn on during the off period, and the voltage across the drain-to-source is also increasing. We suspect this may be due to a malfunction or switching issues, so we tested various conditions to resolve the problem.
Case 1: Adding a capacitor between the gate and source terminals
Case 2: connected 10K resistor between the gate and source terminals.
Case 3: connecting 12V Zener diode between the gate and source terminals.
Case 4: Tuning of gate resistor.
Case 5: Tuning RCD snubber.
We did not observe any improvement in the waveforms for the above cases. I have attached the waveforms of the gate and the Vds across the MOSFET for your reference and understanding.
The first waveform gate pulse and second waveform drain to source @ Vin=48V Iout1=1A, Iout2=2A
