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LM4562: LM4562 oscillation

richard wiskin
Prodigy 60 points
Part Number: LM4562

I have a problem with oscillation. This is a simple buffered volume control for a line stage audio pre amplifier.

Can anyone see the cause. I have played around with the feedback resistors. The gain should be quite low 4 x currently shown. Tried 27pF across the feedback resistors and values of 10k  and 1K for the gain resistors.

 

  • 0
    TI__Genius 16645 points

    Hi Richard,

    After reviewing the schematic you provided, there is nothing that really stands out. Could you provide the layout, there might be some layout concerns causing the instability you are seeing. Also, is it possible to probe what you are seeing as well as the input signal? Could you also clarify the values you have for your decoupling caps for the supplies. We have seen an effect at the output due to improper decoupling in the past. Although it is unlikely.

    Best Regards,

    Ignacio

  • 0
    Prodigy 60 points

    Hi Ignacio

    Decoupling is 100n and 10uf.

    Thanks Richard 

  • 0 in reply to richard wiskin
    TI__Genius 16645 points

    Hi Richard,

    The decoupling caps your implementing should work for this amplifier. Could you please specify what you are seeing with the circuit. Are you seeing oscillations from each channel or just one of them? Is it possible to share scope shots of what you are seeing and the input you are sending in?

    Best Regards,

    Ignacio