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TPA6111A2 with split supply - (150-mW STEREO AUDIO POWER AMPLIFIER)

Arn Roatcap
Prodigy 50 points
Other Parts Discussed in Thread: LM4881, TPA6111A2, TPA6130A2, TPA6132A2

I want to use a TPA6111A2 with a split supply. As you may know, it's pin-for-pin compatible with the old Nat'l LM4881.

It's designed to be used with a single 5V supply - along with output capacitors.

Why I like this old chip is that it can easily drive 16 ohm loads - even small 8 ohm speakers!

But I'm looking for someone who has successfully accomplished this (using it with a split supply).

Here is what I have done so far - will this really work?:

  • 0
    TI__Guru**** 189399 points

    Hi, Arn,

    That will probably work, but be careful with the shutdown pin. You will need to tie it to the +2.9V supply to activate the chip, and -2.9V supply to deactivate it.

    But, being really lazy, I would just use one of our existing parts with a charge-pump to eliminate the need for the output blocking caps. Look at TPA6132A2 or TPA6130A2 for example.

    -d2

  • 0 in reply to Don Dapkus
    Prodigy 50 points

    Mr Dapkus,

    Thank you so much! So that is why I could not get the chip to turn on!

    (I had the shutdown pin tied to the negative supply rail!)

    Corrected, this is the essential circuit:

  • 0 in reply to Don Dapkus
    Prodigy 50 points

    Don,

    I think the original circuit I posted is correct. It should be a logic LOW, in this case -2.9V

    not a logic HIGH which enables the chip.

    Have you actually run this chip from a split supply?

  • 0 in reply to Arn Roatcap
    TI__Guru**** 189399 points

    Hi, Arn,

    Of course, you are correct. About 10 years ago, we inverted our logic on the SD pins since it didn't make a lot of sense the way we did it in the beginning (that was my old bosses idea...). So, yes, you need to tie the SD pin to -2.9V to get it to be enabled.

    This part is really old, and my memory is a little bit fuzzy, but I think the problem may be the fact that you don't have a cap from pin 3 to the negative supply. There is a comparator on the BYPASS pin that has to sense a certain voltage for it to work.

    I have not personally run this device in split supply, but logically, it should work, as ground is merely a concept...

    -d2

  • 0 in reply to Don Dapkus
    Prodigy 50 points

    Don,

    Thanks again for your attention. Actually, I DID run it with a split supply a few years ago - but had no success recently!

    Howsomever, I am certainly open to ideas for something newer that could also drive small speakers. Is their really

    anything else as husky as this old Nat'l chip (for headphones primarily)?