LMR33640: VCC capacitor

Kazuki Itoh

Genius 10760 points

Part Number: LMR33640

Hi team,

My customer wonders if it is allowed to reduce VCC capacitor from 1uF to 0.1uF for a size and cost reason.

I know it is not recommended in the DS.

Could you please let me know the risk to reduce VCC capacitor?

Regards,

Itoh

over 4 years ago

+1 Andy Chen over 4 years ago

TI__Mastermind 34605 points

Hi Itoh,

VCC cap will provide current for driving low side MOSFET, current peak may over 1A, so VCC cap should has enough capacitance to reduce VCC voltage noise, 10V rating should be OK for minor cost down.

B R
Andy

0 Kazuki Itoh over 4 years ago in reply to Andy Chen

TI__Genius 10760 points

Hi Andy,

Do you mean the 10V cap is OK considering voltage derating?

For instance, 0402X105K100CT(1uF/10V/1005/±10% tolerance) is a 10V-rated capacitor, but when 5V is applied, the effective capacitance is 0.4uF. Do you think this capacitor is OK?

Regards,

Itoh

+1 Andy Chen over 4 years ago in reply to Kazuki Itoh

TI__Mastermind 34605 points

Hi Itoh

This cap is OK!

B R

Andy

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LMR33640: VCC capacitor