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Negative Output LDO PSRR test method？

junji ge
Prodigy 10 points

How to measure PSRR and Noise of Negative Output LDO?

  • 0
    TI__Mastermind 37065 points

    Hi Junji,

    Please see this application note: https://www.ti.com/lit/an/slaa414a/slaa414a.pdf.
    In general, the most common PSRR measurement of an LDO requires an AC injection source into the LDO input, typically 100mVpp or so.
    The frequency response analyzer (Venable, Ridley, Omicron, Moku, etc) or a network analyzer will measure the gain difference between ripple on the input of the LDO and the output of the LDO.  The application note uses a specific high bandwidth voltage feedback amplifier.  You can use any high bandwidth op-amp as long as the op-amp can provide the current under test, has sufficient bandwidth of your needs, and has sufficient dynamic voltage to drive the input of the LDO.

    Thanks,

    - Stephen