Posted on March 22, 2017 at 14:35Hello everybody,
I'm working on a power supply with a LLC Stage in it. The LLC has following specifications:
Uin: 385V
Uout: 28V
Iout: 5.75A
Switching Frequency: 300kHz
For the secondary side rectification I want to use a SRK2000A but i have the Problem with a delayed Turn-off of the synchronous rectifier MOSFet's. My selected Turn_off_threshold is 25mV. In the attached Picture you can see in yellow the output of the SRK2000A in red the secondary current in blue the Vds over the MOSFET and in green the resonant current. My schematic is like in the Datasheet but with RD=2kohm. At the High output current of 5.5A the time between the SRK2000A turns off the MOSFET and the current in the MOSFET gets negative is only about 40ns. So there is only a little margin to current reversal. Has anybody an idea to get a smaller delay? Or would it be better if i use a SRK2001?
I'm grateful for any help,
Best regards
Stefan
#srk2000 #synchronous-rectifier
