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OPA1662: issues with opa1662

RIGAS MAKROPOULOS
Prodigy 20 points
Part Number: OPA1662
Other Parts Discussed in Thread: OPA134, OPA1642

Are there any special precautions that have to be considered while dealing with OPA1662s? I am an electrical engineer designing hi-end audio preamplifiers for the past 20 years. Recently, while dealing with 1662s , I came up with a few damaged prototypes (damaged 1662s). In fact, the prototypes was working perfectly for a while and then just unbearable distortion came up, while other two working parts became completely dead. I never had such issues in the past with e.g. 1642s, opa134s etc.Any suggestions??.

  • 0
    TI__Guru* 93105 points

    Hi Rigas,

    That is not expected for the OPA1662. The OPA1662 went through a rigorous product qualification just as the OPA1642 and OPA134 did to prove their reliability. They are different from a technology standpoint in that the OPA1662 is a bipolar input op amp, and the other two are JFET input op amps. But that shouldn't make any difference with regard to reliability. 

    Would it be possible to share the schematic of the circuit in which the OPA1662 has failed? If that can be done, please provide the power supply voltages, input drive conditions, and output load conditions. We can review the circuit and see if anything catches our eye.

    Do you know if the OPA1662 devices that have failed were obtained directly from TI, or one of our authorized distributors? I expect so, but do have to ask to make sure that didn't come from some other source.

    Regards, Thomas

    Precision Amplifiers Applications Engineering

  • 0 in reply to Thomas Kuehl
    Prodigy 20 points

    Hi Thomas,

    thank you for the reply,

    You see it is also strange to me that this happened, mostly because the circuit is a simple Shallen Key high pass filter,

    followed by a preamp stage. Below you 'll find the circuit just for reference.

    I wonder (because it is supposed to be battery powered) if battery misuse (e.g. the wrong polarity) is capable to fry the IC instantly.

    Let me know your thoughts.

  • 0 in reply to RIGAS MAKROPOULOS
    TI__Guru* 93105 points

    Hello Rigas,

    Thank you much for providing your OPA1662 circuit. I find nothing about the electrical design of the two stages that would lead to the catastrophic failure you have experienced.

    A reversed battery would almost certainly destroy the OPA1662 op amps. They are fabricated on a junction isolated bipolar process and there is a substrate diode between the supply pins that is in normal operation reverse biased. If the battery is reversed that diode becomes forward biased and other than the diode forward resistance and the battery current capacity, there is nothing to limit the current. The net result is catastrophic damage to the silicon or blown power supply wire bonds inside the package.  

    I would expect that the OPA134 and OPA1642 could be damaged by a reversed battery connection, but they are JFET input op amps and maybe the two different processes they are fabricated on are more tolerant of a momentary battery reversal than the OPA1662.

    The addition of a robust, unipolar TVS diode from the +9 V supply line to ground would clamp the supply line to the forward voltage of the TVS if the battery is momentarily reversed.

    Regards, Thomas

    Precision Amplifiers Applications Engineering

  • 0
    TI__Genius 10850 points

    Hello Rigas,

    We hope your issue is resolved. I am going to close this thread now. Feel free to reply to to re-open if you have any questions moving forward.

    -Tamara