LMR12015: Feedforward Capacitor

Shuji Ishiwata

Part Number: LMR12015

Hi All,

I have a question about Feedforward Capacitor.

The formula below does not match the capacity of the CFF in Figure 37.
Are there any other conditions or recommended capacitor capacities?

Also, depending on the temperature conditions, the capacity value may not be met. Is there any problem if the capacity cannot be met?

Best Regards,
Ishiwata

over 2 years ago

0 Nancy Zhang over 2 years ago

TI__Mastermind 46850 points

Hi Ishiwata,

Cff as 0.18uF in Figure 37 of datasheet is incorrect and should be typo. 0.18uF is too big and doesn't make sense. The Cff should be lower than 36nF based on equation. Please refer to Figure 41. Fig 41 should be reasonable. Will update the datasheet in next revision.

Hope this helps,

Thanks,

Nancy

0 Shuji Ishiwata over 2 years ago in reply to Nancy Zhang

Mastermind 6125 points

Hi Nancy

Thank you for your reply.
I understand that it is a typo.

There were no comments on the last question below.
Can you give us any comments?

" Also, depending on the temperature conditions, the capacity value may not be met. Is there any problem if the capacity cannot be met? "

Thank you very much for your support.

Best Regards,
Ishiwata

+1 Nancy Zhang over 2 years ago in reply to Shuji Ishiwata

TI__Mastermind 46850 points

Hi Ishiwata,

The feedforward capacitance tolerance or variation should not affect the performance. Our equation is equal or less than. You can place Cff as placeholder on the board. You may not need to populate it if the transient performance can meet your requirement.

Hope this helps,

Thanks,

Nancy

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LMR12015: Feedforward Capacitor