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TPA6111A2: Shutdown behaviour.

Norm Bain
Prodigy 50 points
Part Number: TPA6111A2
Other Parts Discussed in Thread: TPA6132A2

How quickly does the TPA6111A2 turn off when the shutdown pin is pulled high?  Does is turn off without loud clicks or pops from the outputs?  And how quickly does it turn back on when the shutdown pin is returned to ground? 

If the venerable TPA6111A2 is slow to turn off, or delivers a loud pop when turning off or on I will need to hunt around for an alternative (in SOIC) with very quick off-on switching at least similar audio quality and low quiescent current. 

  • 0
    TI__Guru* 95175 points
    Hi Norm,

    Welcome to e2e.
    The turn off is pretty much immediate, as soon as shutdown pin is pulled high the output is reduced, after the output is reduced there is only a variation in the DC level at the output during a short time due to the bypass discharge.
    Regarding the turn on, it takes some more time, in the order of hundreds of miliseconds. This time is related to the value of the bypass capacitor (connected to pin 3). It is recommended to set a reasonable time for turn on so the pop noise is reduced or eliminated.

    If you need a device without pop and quick shutdown response you would like to take a look at the GND centered output devices, like TPA6132A2.

    Best regards,
    -Ivan Salazar
    Applications Engineer - Low Power Audio & Actuators
  • 0 in reply to Ivan Salazar
    Prodigy 50 points

    Thank you Ivan.  I have decided to go with the TPA6132A2 despite the difficulty of hand-soldering these tiny critters, because the advantages of the quick clean shutdown and no need for large output capacitors are worth the effort.  And somehow the engineers have kept the quiescent current to 3.1mA maximum.  Bravo.  I have ordered a little bunch of these amps, and some adaptor PC boards in case I need them.  Let's hope my 77 year old eyes are up to the challenge. My only concern is that the output power may not be quite enough for my very unusual (inefficient) custom headphone arrangement but the only way to know that is to build one and try it.  Running it from maximum recommended voltage will help. 

  • 0 in reply to Norm Bain
    Prodigy 50 points

    I have designed a circuit board but I have one question.  Must the gain pins be connected either high or low, or may they be left floating?  If floating is permissible, what gain results?

  • 0 in reply to Norm Bain
    TI__Guru* 95175 points
    Hi Norm,

    The best practice is to connect them to either high or low. Leaving them open would not set a known state and the gain could be different each time.

    Best regards,
    -Ivan Salazar
    Applications Engineer - Low Power Audio & Actuators