LMR23625-Q1: Bootstrap capacitor and feed forward cap

Masayuki Uchihara

Intellectual 1635 points

Part Number: LMR23625-Q1

Hello Team,

I have schematic review about LMR23625-Q1 from customer. I write it down could you check and give me feedback?

I am awaiting your reply

Masayuki,

************

Questions,

-Our customer wants to add 2 ohm resistor between Boot pin and Boot cap. How do you think about it?

- In my calculating, the Cff (Feed forward cap) is 16pF. But our customer selected 10pF. Is it too small? Could you tell me if we selected too small Cff, how does the device behave?

over 5 years ago

0 Arief Hernadi over 5 years ago

TI__Mastermind 23815 points

Hi,

2 ohm on the boot capacitor should be ok.
Generally converter should be stable even without the CFF value.
If the customer choose a lower CFF probably the transient response it less optimum
Therefore CFF value is only for adjustment dependent upon the transient response (Bandwidth, etc)

Thanks
-Arief

0 Masayuki Uchihara over 5 years ago in reply to Arief Hernadi

TI__Intellectual 1635 points

Hi Arief,

Thanks you for your quick response. I understand these answer. But I have other question about this product.

-Our customer wants to use the inductor of 2.2uH. Our customer's design requirements are almost same as the typical application of the datasheet except output current. In our case, output current is 1A. I think 2.2uH is too low inductance value. I'd like to recommend at least 4.7uH.
How do you think about it?

I am awaiting your reply.
Thanks,
Masayuki

0 Arief Hernadi over 5 years ago in reply to Masayuki Uchihara

TI__Mastermind 23815 points

Hi,

I think the 2.2uH should be ok

Thanks
-Arief

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LMR23625-Q1: Bootstrap capacitor and feed forward cap