LM5176: How to design dithering cap for LM5176

Shaquille Chen

Intellectual 1770 points

Part Number: LM5176

Hi Team,

As title, How to design dithering cap for LM5176?

Datasheet only show equation but didn't show what's the definition of FMOD.

If customer use 400k switching frequency, what should FMOD value?

How many maximum percentage of modulation frequency recommend for design?

BTW, I try to use Webench to enable this function.

But either 200kHz or 400kHz switching frequency, Cdith are 47nF. How to calculate this value?

Shaq.

over 5 years ago

0 Brian (CPM-USA) Cheng over 5 years ago

TI__Prodigy 270 points

Hi Shaq.,

Due to an unexpected event, our apps team will get back to you tomorrow. Thanks.

Regards,

Brian

0 Youhao Xi over 5 years ago in reply to Brian (CPM-USA) Cheng

TI__Guru* 78430 points

Hi Shaq,

FMOD should not be faster than you look crossover frequency, or your loop will not catch up and the FMOD will show up on the output voltage as a low frequency ripple. In other words, you would keep you loop to be fast enough to regulate under the variable switching frequency.

Thanks,

Youhao