PMP21495: PMP21495 frequency

choo523l

Part Number: PMP21495

Hi, I'm Jiyeon Choo.
I have a question about PMP21495.
This DC DC converter has a resonant frequency at 500kHz.
The switching frequency you set is 300-700kHz. Is there a reason you set it like this?

over 1 year ago

0 Sheng-yang Yu1 over 1 year ago

TI__Expert 3650 points

Hi Jiyeon,

We set the resonant frequency and switching frequency high mainly because we want to shrink the board dimension to increase power density. Detail design considerations of this design can be found in the following Power Supply Design Seminar presentation.

https://www.ti.com/seclit/ml/slup399/slup399.pdf

Regards,

Sheng-Yang Yu

0 choo523l over 1 year ago in reply to Sheng-yang Yu1

Prodigy 60 points

Oh, thanks.
I understand why you use high frequencies.
What I was curious about was the frequency range.
I understand that the frequency range of the converter is usually 20% different from the resonant frequency.

0 Sheng-yang Yu1 over 1 year ago

TI__Expert 3650 points

Hi Jiyeon,

When LLC resonant converter has large Lm/Ls ratio, the input/output voltage gain curve will get flat. In order to cover the gain range you need, you will have to have a wider operational frequency range. This is common in LLC resonant converter with high resonant frequency.

Regards,

Sheng-Yang Yu

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PMP21495: PMP21495 frequency