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Offset Voltage adjustment for OP177

Kaos
on Jan 19, 2016

Dear Sir/Madam,

Our customer asked th following question to me.

As for your OPAMP OP177GSZ,

your datasheet shows the adjustable offset voltage adjustment range is +/-3mV typ by adding 20kohm POT on Rp.

So if we need it +/-6mV, then what is the external Rp value?

10kohm POT?

V+,V-=+/-15V

Maybe this was shown in past sled here but I could not find it sorry

Thanks Kaos

  • 0 on Jan 20, 2016 11:56 PM

    Thanks Harry,

    Good advice. I will know the temperature problem to our customer.

    Does Autozero-AMP means current Zero-drift AMP?

    I will recommend your ADA4522-2 to our customer if so.

    Thanks Kaos

  • 0 on Mar 15, 2016 1:49 AM

    Hi Harry,

    Our customer did the following schematic circuit that you instructed.

    But the adjustable offset voltage became narrow range around +/-2.7mV.

    VR5=10kohm

    Can your instructed way apply for the following circuit too?

    Please advice us thanks Kaos

  • 0 on Mar 15, 2016 3:05 PM

    Hi Harry,

    Customer have put your OP177 on their inspection device and it have fixed so it cannot replace it to another recommended new device like a ADA4638.

    Therefore customer followed your instructed way adjust the output offset voltage.

    You commented to put the 10k ohm POT on the 1-8 pin, but customer could not bring the expected result.

    So he asked why the adjustment result not so good to us.

    This is the reason why he ask again for OP177.

    As for Instructed way adjustment offset voltage, does it support for V/I converting circuit or not?

    Thanks Kaos

  • 0 on Mar 15, 2016 3:38 PM

    Here is additional info.

    Customer is using as X1 buffer amp.

    Thanks Kaos

  • 0 on Mar 17, 2016 7:34 PM

    Hi Harry

    Here is additional question.

    Which is correct?

    Resistor value between pin1-pin8

    become small value=reduce the offset voltage or growth the offset voltage ?

    become large value=reduce the offset voltage or growth the offset voltage ?

    I could not simulate your ADIsimPE due to that there are not pin1 and -pin8 OP177 symbol mark.

    Thanks Kaos