Multiple PSUs - single Y1 cap

Posted by: Kris Verbeeck on 06/09/2011

Hi,

I'm putting 10 Linkswitch-PH LED drivers on single PCB and I'm looking to avoid redundancy as much as possible. So I'm combining input filter, bridge rectifier etc. However, now I'm looking at the Y1 cap between secundary and primary. I'd say that if all RTN of all secundaries are the same I can get away with a single Y1 cap? Thoughts?

br,

Kris Verbeeck

Comments

We have not tried to do such thing. I believe if you need to do that, you need to short all the output returns and all the +DC high voltage bus. The Y cap is not the only factor for EMI. You have to consider PCB layout, transformer construction, and so on. If the whole system pass your EMI requirements with a single Y cap. Then I do not see why not to use only one Y cap.

Thanks for the reply. Not sure what you mean by connecting the +DC HV bus? This is a single stage PFC corrected LED current driver?

ok, I understand now, The DC bus will be common to all the power supplies. So you need to connect all the OUTPUT Returns together to connect them to the Y cap