UCC28950: Pmp8740 ADEL setting

Nidheesh BR

Part Number: UCC28950
Other Parts Discussed in Thread: PMP

Hi,

In PMP 8740 design why to make the adaptive delay (ADEL) as static as it is supplied from Vref. So ADEL voltage is 1.8v, which means minimum delay.

So if I want to make it dynamic I have to populate R8 and make R1 DNP.

If so, I will get a delay around 400-500nS at no load and which may reduce during loading(As CS pin voltage increases). Which is according to datasheet description.

So I want to know that, why the designer has not adapted to this scheme. are there any chances of issues?

over 5 years ago

0 Teng Feng over 5 years ago

TI__Genius 13660 points

Hi Nidheesh, an expert will get back to you tomorrow.—— Teng

0 Bliss Zhou over 5 years ago

TI__Expert 3470 points

HI Nidheesh

The designer uses this function or not. I think it depends on whether he needs it. you can use it if you want. you just need to control the dead time is suitable at all condition. there is no issue.

thanks

0 Nidheesh BR over 5 years ago in reply to Bliss Zhou

Expert 1295 points

Thank you, Bliss & Teng, for your valuable replays.

I have varied the ADEL resistor in the prescribed range and getting dead time variation as explained in the datasheet. So if I am adding this adaptive delay I can counteract the regulation voltage dip of the transformer by adding some extra duty cycle at higher loads.

Thanks&Regards

Nidheesh.

0 Bliss Zhou over 5 years ago in reply to Nidheesh BR

TI__Expert 3470 points

Nidheesh，

if you don't have more questions, I will close this thread.

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UCC28950: Pmp8740 ADEL setting