Hi,

based on DER-294 (PFS) and DER-368 (TFS) we have designed a a complete PS.

TFS primary clamp design is identical with DER-368.

VR3=P6KE150A

R6=100R 1/2W

C2=2,2nF/1kV

Measure DSB level to 595-600Vp, well below DSBmax 725Vp.

Recommended DSBworking <= 675Vp given a margin of 50Vp (DSBmax)

But the clamp overheat at 1A main load.

Measure approx. 188Vp over VR3+R6.

Can a higher Vbr for VR3 be selected ?

P6KE180A or perhaps P6KE200A ?

PFS safegard the Vbus (HD) to 395Vmax+30Vpmax=425Vpmax ( according to spec.)

If the answer is no, kindly describe a methode to lower the voltage stress of VR3+R6.

Any particular critical board design check up´s ?

Kindly advise.

BR/tomasf