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LM741: Op-Amp Failure

Adam Torrance
Prodigy 20 points
Part Number: LM741

I have encountered multiple failures of the LM741CH operational amplifier ICs. In operation, these ICs are configured for a voltage follower configuration as part of a most negative input voltage auctioneering circuit. The failures observed were not hard failures in that they were still providing an output however, the output did not correspond to the input voltage and was out of tolerance for the voltage follower configuration. I was wondering what failure mode for this op amp was possible in order to produce an output that did not equal the input when set up for a follower configuration. I know they do have offset null pins that could impact the output, however, these pins are not used or connected when in use in this application. Both diodes were checked to be functioning properly. Thank you.

  • 0
    TI__Guru**** 153686 points

    Hello Adam, Welcome to the e2e forums.

    What are the voltages at all the nodes? Do all inputs have a good input common mode voltage?

  • 0 in reply to Ron Michallick
    Prodigy 20 points

    Hi Ron. Thank you! The voltages at the non-inverting inputs, pin 3 of each IC varies from -8 to -10VDC and the output is measured to ensure that it equals the most negative input voltage. It is also tested at inputs of 0 to 2 VDC to pin 3 and again the output is measured to ensure it equals the least positive input in this case. The supply voltages to the ICs are at +/-15VDC with a +/- 0.1 VDC tolerance for each. All input voltages, differential inputs, and supply voltages are within those listed on the datasheet. Thank you.

  • 0 in reply to Adam Torrance
    TI__Guru**** 153686 points

    Adam,

    The bad output is a voltage that is not the same as the lower of the inputs. Higher or lower, I don't know. The inputs are claimed to be good so pin 3 is OK. Pin 6 is protected by pin 2. Therefore something could be happening to pin 2. Where does pin 2 go. Does it go to a connector?