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LM5025: typical application vs. PMP7756

Yen Ting Chu
Intellectual 1350 points
Part Number: LM5025

Team,

My customer is designing with LM5025 and leveraging PMP7756. They realize that the design at LM5025 REF pin is different. In LM5025 datasheet typical design, REF pin is connected to 0.1uF, while in PMP7756, REF pin is connected to an extra 23.2k ohm in parallel. Would you please explain why an extra resistor is connected in parallel in PMP7756? Thanks.

Best regards,

Andy Chu

  • 0
    TI__Mastermind 31580 points

    Hi Yen,

    I do not see the name of the original designer on the schematic so I cannot refer you to him directly.

    I believe the 23.2K resistor in PMP7756 connects from the REF pin to the CS2 pin and it will affect the length of of time required to charge the filter cap on the CS2 pin to 0.25V. If a lower value of resistor is used it will increase the time taken to charge the filter cap so the PSU will operate longer in overload condition and if a higher value is used it will reduce the time the PSU will operate in overload.

    Regards

    Peter