Solution Finder

150W Topswitch flyback from 385VDC input (24V, 5A)

Posted by: treez on Mon, 05/03/2021


We wish to do a TOPswitch flyback for 150W from 385VDC PFC output.

Why does much literature say this is unadviseable? (not PI literature)

Efficiency doesnt matter, this PSU will rarely get above 10W load most of the time......mind you, on rare occasions it may need to do 150W for 1 hour and not fail due to overheating.

Can we use a HiperPFS PFC stage?...the one with fet and diode incorporated?

If so, can we disable  the HiperPFS as most of the time we will be on light load.

Also, what is VAC input goes up to does HiperPFS/Topswitch solution look then?

Log in or register to post comments


Submitted by PI-csbabu on Tue, 05/04/2021

Hi Treez,

          If efficiency not primary,  PFC plus flyback combined architecture can be used for your application. As you know HiperPFS-3, the switch and diode both rated to 530V maximum voltage stress. So at 300VAC, the transient load may stress the device. HiperPFS3 doesn't have disable function based on load but you can still keep PFC on at light load, if you are not looking for efficiency.