LM65625-Q1: Input Capacitor Selection In 48V System

Eileen Hu

Intellectual 1980 points

Part Number: LM65625-Q1

Hi team,

I'd like to how to select input capacitor in 48V system application. In datasheet, there is only a example of 24V input.

VIN: 36~64V

VOU: 5V

IOUT: 50mA

Ripple rate: 30%

FSW: 2.2MHz

Regards,

Eileen

4 months ago

0 Tony Koulong 4 months ago

TI__Genius 10090 points

Hi Eileen,

You can used the same input capacitors for your 48V system. Also, plan to add a damping electrolytic cap on your input to filter all the input ringing. Thanks.

0 Eileen Hu 4 months ago in reply to Tony Koulong

TI__Intellectual 1980 points

Thank you Tony,

Could you help to review this schematic of LM65625-Q1? Thank you.

Regards,

Eileen

0 Tony Koulong 4 months ago in reply to Eileen Hu

TI__Genius 10090 points

Hi Eileen,

I think they might be an error while you uploaded the schematic.

0 Eileen Hu 4 months ago in reply to Tony Koulong

TI__Intellectual 1980 points

Hi Tony,

Is this one OK?

Regards,

Eileen

0 Tony Koulong 4 months ago in reply to Eileen Hu

TI__Genius 10090 points

Hi Eileen,

Your schematic looks okay. Just couple of suggestions for you;

1- I would encourage to add a damping electrolytic cap on your input. That would help to suppress the input filter resonance. if space is an issue, you can used a ceramic cap in series with a low a ESR resistors in mΩ.

2- You can change C8 on the output to 100nF.

0 Eileen Hu 4 months ago in reply to Tony Koulong

TI__Intellectual 1980 points

Hi Tony,

I'd like to check with you if X7S capacitor can be used at C9 (for VCC)? Datasheet recommends X7R, but the customer doesn't have it.

Regards,

Eileen

0 Tony Koulong 4 months ago in reply to Eileen Hu

TI__Genius 10090 points

It should be okay. The big difference is just the tolerance. That should be okay.

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LM65625-Q1: Input Capacitor Selection In 48V System