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DRV134: Excessinve THD + N on random parts

CHARLES MAPLES
Prodigy 10 points
Part Number: DRV134

I have an issue with about 10% of the DRV134  Audio-Balanced Line Drivers.  On about 5 to 10% of the units tested the THD + N level is an order of 10 times higher than the published specification.  Most of the parts perform as published with a nice flat noise floor when swept from 20 to 20KHz.  

We are testing the parts with a Audio Precision System one audio analyzer.   The test frequency is 1,000 Hz with the bandwidth set from 22 to 22,000 Hz at 0 dBm level.   For good parts we are measuring a THD + N on the average of 0.001 %  while bad parts are typically 0.01 % tested at 1,000 Hz.

Confidentially, we had the same issue back in 2004 when the part was available from Analog Devices as the SSM2142  At that time Analog Devices stated " We did have a serious manufacturing problem with the part last year which should be resolved by now ".  Analog Devices had then resolved the problem and all the parts after that date until now worked as expected.  Since they resolved the issue in 2004 we have continuously used 10,000 + of this part with no issues.  I do not know if your DRV134 is the SSM2142 rebranded but it sure seems to have the same issue.

Please get back to me on that as soon as possible as we have a production run shut down awaiting a response.

  • 0
    TI__Prodigy 715 points

    Hi Charles,

    ADI's SSM2142 is a competing device, but TI has no affiliation with ADI.  So I'm afraid their manufacturing miscue circa 2004 is unrelated to the issue you are facing today on the DRV134.  By the way you put "confidentially" but this is a public forum, so you might want to modify your original post if possible (though I'm not sure if that is truly confidential information or not).    

    Regarding your issue with the DRV134, can you please provide a few more details?

    - Can you confirm that you've done an ABA swap and shown 'good' units pass in a 'bad' board and vise versa (alleviates test setup root causes)?  Does returning 'bad' units back to the 'bad' board cause the issue to return (alleviates solder mishaps)? 

    - Have you been able to look at noise separately from THD+N to determine if the degradation is coming from THD or Noise? 

    - Have you noticed any pattern in your 10% of poor performing units?  e.g. they all came from this one lot, or it seems evenly spread across all orders, etc

    - Can you provide more details such as power supplies, loads, signal magnitude, etc?  A schematic can be shared confidentially in a private E2E message if need be.

    Thanks,
    Scott