PMP10395: Purpose of MOSFET

Nesh Johny

Expert 1310 points

Part Number: PMP10395

Dear Sr,

Could you please share the detail about the operation of R3 (0.1E) resistor and Q6 MOSFET.

How it helps the forward active clamp converter.

Thanks and Regards,

Nesh

0 Robert Taylor1 over 6 years ago

Hi Nesh,

Q4 and Q6 are in parallel, it is a bit deceiving the way it is drawn. Those are the main forward FETs.

R3 is the reset resistor for the current sense transformer and it also serves a purpose of damping the current spike from the primary FETs.

Hopefully this helps.

Thanks,

Robert

0 Nesh Johny over 6 years ago in reply to Robert Taylor1

Expert 1310 points

Dear Sir,

Is R3 as reset resistor for the current sense transformer really mandatory?

Because many other designs I'm not finding that as shown below:

thanks and regards,

nesh

0 Robert Taylor1 over 6 years ago in reply to Nesh Johny

Nesh,

Yes it is necessary to prevent the transformer from saturating. Including it on the primary side just helps to damp the circuit also.

Thanks,

Robert

Simulation, hardware & system design tools forum