LM5642: LM5642 Schematic Review Request.

Nicky Lim

Genius 3195 points

Part Number: LM5642

Hello,

Make board as below schematic, but its output is not stable.

Could you review below schematic and let me know what is the problem ?

Regards,

Nicky

over 7 years ago

0 Nicky Lim over 7 years ago

Genius 3195 points

Hello,

Is there any updates?

Please let me get your answer ASAP.

Regards,
Nicky

0 JohnTucker over 7 years ago in reply to Nicky Lim

TI__Guru**** 191445 points

This was posted over the weekend. Let me see if I can find someone to review it this week.

0 Terry Allinder over 7 years ago in reply to JohnTucker

TI__Expert 3535 points

Nicky,
Can you tell me what your input voltage range is, min, typical, and maximum is, What's the load current for each output. Under what conditions is the output not stable.
Terry Allinder

0 David Baba over 7 years ago in reply to Terry Allinder

TI__Mastermind 26350 points

Also I would check the input filter stages to make sure they are well damped. typically to dampen an input filter stage you will need a capacitance that is at least 4 x greater than the existing input CIN. You may want to replace the 220uFs with lower value Cermaics and ensure these are located close to the Buck FETs. Then I would add a dampening Cin close to the input filter making sure Cdampen = 4 x Cin Buck. Also Make sure the Series ESR of the Cdampen >0.5ohm (typically).

Power management

Power management forum

LM5642: LM5642 Schematic Review Request.