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LMP91000: About maximum external gain resistor

Michael Jeong1
Expert 2630 points
Part Number: LMP91000

Hello Expert,

We want to know about maximum value of external gain resistor.

We already checked maximum value in the data sheet like below captured.

Depending on the type of gas, we may need a high amplification ratio.

Test results show that the amplification is good up to 2M ohm externally.

I would like to know if there are any problems when using up to 2M ohms as an external resistance.

Do we have to use by 350Kohm?

Could you please check and give us your feedback?

Best Regards,

Michael

  • 0
    TI__Genius 12255 points

    Hi Michael,

    We recommend sticking to the maximum external gain resistor value of 350Kohm. Larger resistance values will cause distortion, oscillations, and instability. Up to 2Mohms may have worked for you in a few parts but it's likely that you would see failures in your system when moving to higher quantities. You may find it helpful to instead increase Rload to bring the measured sensor current up as it enters the transimpedence amplifier.

    Regards

    -Alex Thompson