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TPA2006D1 parallel operation

Jonathan Bischof
Prodigy 60 points

Other Parts Discussed in Thread: TPA2038D1, TPA2037D1, TPA2039D1

Hi community

I'm designing an audio amp for cellular phone application which will need two amps - it's a security device which has a very powerful rear speaker in addition to the standard speaker you'd put on your ear. Due to the high current consumption, I can't use an audio switch, so I need two separate amps connected to the same audio source (see schematic below). These will be switched with the respective amp enable signal.


Now, I'm not sure if I can just connect the two inputs together in this way. Would there be any interference from the other amp (which is in shutdown mode) when using one amp at a time in this configuration?

Inputs are connected together after the input Gain conrol / HPF to save components. I'd like to keep it that way, but if it helps I could interconnect the amps before the gain / hpf circuit and add one circuit for each amp.

The Audio source signal is the output from an audio voice codec IC (MAX9860).

Any help is much appreciated!

regards

Jonathan Bischof

  • 0
    TI__Genius 16645 points

    Hi Jonathan:

    I do not suggest connecting the two devices together in the manner suggested in the drawing.

    The connections between IN+ and its resistor and IN- and its resistor should be minimum length to avoid noise pickup, GSM buzz, etc.  It would be best to use separate input resistors for each amplifier.  You could use the same DC blocking caps, but generally, it is preferable to keep them separate.

    Please let me know if you have further questions.

    Also, take a look at one of our newer amps like the TPA2038D1.

    Rgds,

    Fred

  • 0 in reply to Fred Shipley
    Prodigy 60 points

    Hi Fred

    Thanks for your quick response! I had a look at your suggested newer amp. It seems to be a very good replacement having a much smaller footprint and eliminating four input resistors (on the two devices used).

    If we don't need the option to select the gain, are the fixed gain models TPA2037D1 and TPA2039D1 a better or worse choice regarding future availability and maybe stability of operation (e.g. noise immunity due to the additional GND connection)?

    regards

    Jonathan

  • 0 in reply to Jonathan Bischof
    TI__Genius 16645 points

    Hi Jonathan:

    The TPA2037D1 and TPA2039D1 are both good choices, too.

    All three amps are used in current portable devices and should be available for a long time.

    The TPA2038D1 is as stable as the other two choices due it its internal layout being able to accomodate one less GND pin.

    Thanks,

    Fred