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LM25085: Rfb resistor

Moon Wang
Intellectual 1285 points
Part Number: LM25085


Tool/software:

Hi Expert,

I found the content in datasheet said the value of Rfb typically lower than 20kOHM as below picture:

Does the value of Rfb1 and Rfb2 have potential negative impact if they are larger than 20kOHM? 

My customer selected hundreds of Ohm for the resistor and the overall function is normal. Could you please help check if there are some potential issue?

BR,

Moon

  • +1
    TI__Mastermind 22300 points

    Hi Moon,

    Generally, larger resistor values may couple more noise into the FB node. Smaller resistors will impact the light load efficiency. Those are the main risks of having resistors which are too large, and resistors which are too small.

    If they see no issue, it will probably be OK. However, we do recommend staying within the datasheet limits.

    Since they are using larger resistors, their feedback my be a noisier than is typical.

    Best regards,

    Ridge