LM20145-Q1; the voltage value of capacitor at VCC pin

Takao Yamamoto

Genius 4135 points

Dear all,

At WEBENCH, why you select 25V capacitor?

Could you teach me the reason?

*see attached file

LM20145WEBENCH.pdf

At data sheet, you select 6.3V capacitor.

What is this difference?

Which one should we choose?

Best regards,

over 8 years ago

0 Clancy Soehren over 8 years ago

TI__Mastermind 23810 points

Takao,

This post belongs in the non-isolated DC/DC forums, so I moved it there for you.

-Clancy

0 Takao Yamamoto over 8 years ago

Genius 4135 points

Dear all,

Could someone answer this?

From data sheet, VCC is 2.95V(max).
So, should we select more than 3.0V capacitor?

I think 25V capacitor is too large.
How appropriate value of this capacitor?

Best regards,

0 JohnTucker over 8 years ago in reply to Takao Yamamoto

TI__Guru**** 191445 points

You should select a somewhat higher voltage rating capacitor than 3 V. Ceramic capacitors are subject to dc bias effect where the actual capacitance decreases as the applied dc voltage increases towards the rated voltage. I would probably use a 10 V capacitor in that application. the datasheet examples specify 6.3 V rating, so I'm sure that is acceptable as well. No need whatsoever to use 25 V rating.

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LM20145-Q1; the voltage value of capacitor at VCC pin