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opa544: OPA544 drops 4dB gain

Peter Pfeiffer
Prodigy 30 points
Part Number: OPA544
Other Parts Discussed in Thread: OPA544

I have a device that use the opa544 as audio amp. This device is manufactured for for several years with no problems.

Some devices of the last produced batch accidental have a too low output level.

The opa544 is used as non-inverting buffer with a gain of 10dB  (1 + 100K/47K). From time to time the gain drops by 4dB.

Up to now I can not identify any reason for that. So my questions:

1. The opa544 has the production code 53Z02SV. Is this a valid code ?

2. Is there any known issue about opa544 with this code

Best regards

Peter Pfeiffer

  • 0
    TI__Intellectual 1095 points
    Hi Peter,

    I try to understand your issue but I have to get some information. Can you please share:
    - a schematic of the application
    - which frequency/frequencies, load, supply voltage is used
    - what is the operating temperature range

    Since the OPA544 is a power op amp it can face high temperatures. Looking at the datasheet this can lead e.g. to changes in Gain-Bandwidth Product and thus in the resulting gain. At high frequencies the output voltage is additionally limited by the slew rate. Exceeding this range can cause a distorted signal.
    To reassure: you said the gain drop happens from time to time. Do you mean that in the initial state there is a gain of 10dB changing so far randomly to 6dB and after a certain time back to 10dB? Or do you have to switch off the device and wait for it to recover? Or does it even stay at 6dB after it changed once? Does it drop at once or does it take some time till it settles at 6dB?
    Did you monitor the temperature of the device during this occurrence?

    Best,
    Miriam
  • 0 in reply to Miriam Mesek
    TI__Intellectual 1095 points
    Hi Peter,
    do you still face this issue? If you need more help, please reach out.
    Best,
    Miriam