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LM5642: LM5642 Schematic Review Request.

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

  • Hello,

    Is there any updates?

    Please let me get your answer ASAP.

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

  • 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
  • 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).