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LM51551-Q1: Application Note Diode Rating D3

Part Number: LM51551-Q1


I am currently investigating LM51551-Q1 for an application.

When studying Application Note SNVA866 I was wondering about Diode D3.

You are writing this is an design with attempted operation in CCM. Therefore I would assume D3 is used as freewheeling path for the transformer current during (1-D)T. This would mean it needs to be able to carry the max. average current of IL. during (1-D)T.

With calculation above, I would assume:

I_D,av=(Pout,tot)/(V_sup,min*d)*(1-d)=20,2W/(18V*0,357)*0,643=2 A

You selected a 1 Amp Diode. ES1C-13-F

Is this current rating still sufficient? Did make any false assumptions about the operation of LM51551-Q1?

Would be very grateful for any help!

Thank you very much!