PFS4 Vfb(off)

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Looking at the datasheet for the PFS4 I see the specs for Vfb(off) as 0.57 Vmin. If I understand this correctly, the PFS can be forced into a shutdown if this pin is pulled low.

Can someone please confirm this is correct, and also advise if there would be any problem in doing so, or alternatively advise another way to turn off the switching of the PFS (appart from open Vcc I mean).


Hi subx99,

Thank you for your interest in using Power Integrations' part.
Regarding your question, instead of using Vcc to turn-off PFS switching it is recommended to use Vpin instead. Pulling it down to ground will turn-OFF the PFS, then releasing will turn-ON back the PFS. The Vfb 0.57Vmin is just a start-up fault protection, when it didn't exceed the Vmin threshold when there's AC input or at start-up, it will trigger fault which indicates that there's something wrong possibly with the fb loop or the output itself.