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PGA2310: Loud pop on power up/down

David Lake
Intellectual 300 points
Part Number: PGA2310
Other Parts Discussed in Thread: TPS7A39

When the PGA2310 turns on or off it makes a loud pop peaking at 2v, how can I stop this happening? This is the power on waveform on the output:

  • 0
    Genius 3945 points

    The usual advice from us audio-production professionals is to turn the amplifiers and powered speakers on last, after all upstream things are on.

  • 0 in reply to Andy Peters
    Intellectual 300 points

    The problem with that is I'm using this in a DIY headphone amplifier and the PGA2310 uses the same dual 15v supply as the driver.

  • 0 in reply to David Lake
    TI__Expert 6400 points

    Hi David,

    Unfortunately, PGA2310 is not designed with pop-free architecture.
    Therefore, some customers insert a switch such as relays between PGA2310 and loudspeaker/headphone driver.
    While, I suppose the symmetrical supply ramping (e.g. TPS7A39)  may help to suppress popping noise during power on/off, but it is very difficult to completely eliminate it unfortunately.

    Thank you and Best regards,
    Iwata Etsuji

  • 0 in reply to David Lake
    Genius 3945 points

    A relay or a shunt FET is a common way of holding off the output connections until power supplies have stabilized.

  • 0 in reply to Andy Peters
    Intellectual 300 points

    The power down transient is also rather extreme, I would be relying on the relay or whatever it is I would use to turn off before the PGA2310.

  • 0 in reply to Iwata Etsuji
    Intellectual 300 points

    How would I stop the power down transient which is even more extreme?

  • 0 in reply to David Lake
    TI__Expert 6400 points

    Hi David,

    Is it difficult to turn off a relay or headphone driver before turning off PGA2310?


    If you are using the shared power supply for both PGA2310 and the headphone driver, the higher decoupling caps on PGA2310 supply pins may help to have more delay during headphone driver turning off. (but please note that higher decoupling cap causes higher popping on PGA2310 unfortunately.)
    If you are using the separated power supply for PGA2310 and the relay or headphone driver, it helps to turn off a relay or headphone driver before turning off PGA2310.

    Best regards,
    Iwata Etsuji

  • 0 in reply to David Lake
    Genius 3945 points

    An old trick used to mute audio outputs is a shunt (to ground) N-channel JFET. See, for example, here (and scroll down to section 2).

    The N-channel JFET is on when its gate is at 0 V, which means that the amplifier output is shunted to ground. To enable normal operation, that is, turn off the JFET by bringing its gate very negative, like to perhaps the negative rail.

    As the article notes, JFET on resistance is on the order of single- or double-digit ohms (not milli-ohms like a MOSFET) so this limits the amount of attenuation. I would imagine that 40 dB of attenuation suffices for power-on/off muting.

  • 0
    Intellectual 300 points

    I got a TE D3023 5v relay for the amplifier output and powering it from the +15v supply via a 10v zener diode it turns on after the power on pop has settled and powers off before the power off pop begins so problem solved!