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Query about OP467

Hi, there

Seeking your technical advice regarding part OP467 applied in my circuit, please see the following problem statement.

Refer schematic below, U38A & U38B is Analog Devices part (OP467), I facing problem where the standby voltage at line ‘X_Temp’ is as high as -1.6V, whereas voltage measured from a  good part is at the range from

-0.051V to -0.081V. With the higher voltage at ‘X_Temp’, my test will definitely failed.

The reject quantity is 8 out of 10 boards. The 2 boards that passing the test are using same OP467 with same date code (1331).

By the theory explanation, the Op Amp should be able to work as a buffering circuit and always ensure the voltage Vout feedback to Vin- to be always near to zero volt.

Please see the following table of voltage comparison in between a good board and bad board.


Voltage from pass and Golden board

Voltage from a few failed boards


‘- 0.055V to -0.081V

-0.8V to -1.6V









-0.85V to -1.6V








  1. 0.36V
  2. 0.85V to 1.6V





  1. 0.83V
  2. 0.37V

Performed evaluation to swap the OP467 in between a good board and failed board, the failure is follows the OP467. So I can conclude the test failure is coming from OP467 itself.

Anyway, haven’t say the part OP467 is defective but could be the reason of component matching or tolerance issue. (Seeking your advice on this)

Be noted that, the part has been run in mass production and this is the first time facing this problem.

And the resistance for R133 with 499Kohm is pre-designed and run for quite some time and it is in the mass production now. This problem is a recent case.

Could you please help give some comments on the issue?




  • WayneQ,

      You probably have some "golden" parts where the input bias current is maybe 100 nA.

    Then you get some parts that are maybe 400 nA.

      The max input bias current for the OP467 is 600 nA.  Times the 499k is 0.3V.

    This is a poor design.  If you really want to build an integrator with 499k and 0.47uF,

    you have to use an op amp with very low input bias current.

    We have seen designs from other customers that were in production for two years,

    five years, or in one case, eight years, and then they got a batch of parts that

    were a little different, but still within the min/max numbers in the spec table.

    You have another problem:  Clamping the output of an op amp (U3B) running on +/-15V

    with a diode to +5V will result in the op amp going into short circuit current limit which

    will greatly affect long term relliability.

    Another possible problem would be if V+ comes up before V- and the V- pin is pulled above

    ground.  This will forward bias the base-collector junction of the input transistor and result

    in excess current flow with R325 and R326 equal to zero ohms.  They should be at least 5-10k.


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