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INA143: Does the drop in the CMRR correlate to a drop in the PSRR for this INA143AU device?

Marvin Cantos
Expert 3525 points
Part Number: INA143

Hi Team, 

Good day. I am posting this inquiry on behalf of the customer.

"We are currently using the INA143U amplifier in our design and looking to use the INA143UA as a substitute device due to availability issues.  In comparing the two devices I see the CMRR is 80db for INA143UA and 86db for the INA143U.  I also see the PSRR at 20khz for both devices is at -30db.  Does the drop in the CMRR correlate to a drop in the PSRR for this INA143AU device?

Specifically, if the CMRR for the INA143UA is 6db less than the INA143U, does the PSRR also drop 6db for the INA143UA in comparison to the INA143U?"

Please help to advise. Thank you for extending your help.

Kind regards, 

Marvin

  • 0
    Guru 140200 points

    Hi Marvin,

    be careful, you compare a DC minimum specification given in the "specifications" with a typical AC specification given in the "typical performance curves". Between DC and AC specifications there's usual no clear correlation. Or would you expect a higher bandwidth from a chip showing a lower input offset voltage?

    Also keep in mind that the curves are only showing typicals. They don't give you any guarantee.

    Kai 

  • 0
    TI__Mastermind 48226 points

    Hi Marvin,

    The CMRR differences at DC are mainly contributed from the grade differences. As Kai indicated, the listed minimum specification is a typical and possible low end figure; there are no clear correlation in AC performance can be concluded between CMRR and PSRR in two grades. The typical AC performances are represented by the captured graphs shown below.    

    If you have additional questions, please let us know. 

    Best,

    Raymond