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LM7322: LM7322 high input bias current

nataut
Prodigy 40 points

Part Number: LM7322

I'm using the LM7322QMA/NOPB operation amplifier in a project, The opamp is powered with 24 V single supply, I measure 0.5 mA to the inverting and non inverting input pins. Based on the LM732x datasheet indication the input bias current has to be less than 0.002 mA. I tried the LM7322MAX/NOPB but the measured value is the same.

How is it possible?

TI field application engineer, could you explain me why?

Many thanks

Regards

  • +1
    TI__Guru**** 174096 points

    Hello Nataut,

    Do you have close to 8V difference between the two input pins? There are Zener diodes that protect the inputs form high input voltage difference.

    This chart is input currents versus input voltage difference, [Vin+] - [Vin-] 

  • 0 in reply to Ron Michallick
    Prodigy 40 points

    Hello Ron,

    many thanks for your kindly response.

    Yes, in my case, the maximum differential voltage is 8V. In the LM7322 datasheet there isn't the chart you show me or any other equal information. It seems to me there is only the maximum differential voltage value, that is +/- 10V, which in any case is greater than 8V.

    I think the datasheet should be clearer

    Regards