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OP2277 Noise

Ian Mantle
Prodigy 80 points
Other Parts Discussed in Thread: OPA2277, OPA277

Hi

I'm using OP2277 SO8 parts in a low noise design that we have been producing for around 10 years.  I have recently produced a batch that uses 2 x OP2277 parts per channel and have experienced intermittent low frequency 'popcorn' noise which has disappeared when I have substituted devices.  Apart from the noise the devices appear to function correctly.

Is this a problem that you have seen before that might be a batch problem?  Can you test the parts if I return them?

Thanks

Ian

  • 0
    TI__Guru 63700 points

    Ian,

    All bipolar input op amps like OPA2277 are prone to exhibit a popcorn noise which is caused by electrons being intermittently trapped as they travel across a p-n junction and thus it is a function of a wafer lot (defect density in the silicon crystal).  However, we have experienced very few cases of OPA2277 having this issue which I expect is a result of the large size of the input transistors used that tend to attenuate the effects of any pops.

    All in all, we are in a process of adding a popcorn noise screen to the production final test solution that should identify vest majority of the suspect units.  What is the percentage of defective units you experience in the latest batch?  If the number is significant and you wish to get them replaced, please contact the distributor where you acquired the units.

  • 0 in reply to Marek Lis
    Prodigy 80 points

    Hi Marek

    Thanks for your response regarding the OPA2277 popcorn noise.  Can you tell me whether the additional screening test has been introduced as I am shortly going to build more units which use them.

    Thanks

    Ian

  • 0 in reply to Ian Mantle
    TI__Prodigy 10 points

    Hi Ian,

    The popcorn noise screen has been implemented at final test.

    Thanks,

    Pooja

  • 0 in reply to Pooja Singh1
    TI__Mastermind 20387 points

    Ian,

    One additional comment.  Popcorn noise is generally a bias current noise.  So, reducing the impedance connected to the OPA277 input and feedback network can reduce the impact of the popcorn noise.  Attached is an article to provide some additional background.

    Thanks

    Art Kay, Op Amp Apps Manager

    noise8-Feb 2008.pdf