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TPA6203A1 Application Issue

Other Parts Discussed in Thread: TPA6203A1

Hi All,

In a portable, battery powered design, we're using the TPA6203A1 audio amplifier to drive an 8 ohm speaker. It's set up using the application schematic shown in figure 30 of the data sheet. I've attached the section of the relevant schematic diagram.

The "DAC" input as shown is fed by the onboard DAC of the freescale MK20DX256VLH7, configured using in the internal voltage reference (and hence the output is biased at 1.2V / 2 = 0.6V).

However, we are finding that whilst initially the design works fine, after some time, the audio amplifier starts exhibiting artefacts and dips in volume, followed by ceasing working completely. 

Any help would be greatly appreciated.

  • Hello Lestyn

    Welcome to E2E, thanks for your interest in our products.
    I think that you could have a power dissipation problem. That could be happening because the device is activating the thermal protection due to bad PCB layout or to the load, have you tried to use different loads?

    Best Regards
    Jose Luis Figueroa
    Audio Applications Engineer | A-Team
  • Hi Jose,

    Thanks for your reply. This was my initial thoughts too, however, when cold-starting the device (having been turned off for more than an hour), it is continuing to exhibit the same behaviour. It appears as though the chip itself is being damaged. De-soldering and replacing the amplifier appears to fix it, albeit temporarily, until the new IC continues exhibiting this behaviour.
    The PCB layout is using a small copper pour on the top layer, with thermal vias through to a ground plane on the bottom layer (it is a two-layer board).

    I haven't tried with a different load; I only have 8 ohm speakers to hand currently.

    Investigating it with an oscilloscope, I've found some interesting behaviour whereby the application of the oscilloscope probe on the input signals sometimes briefly corrects the issue.

    Kind Regards

  • Lestyn

    If It is possible, you could try with a different load in order to discard a problem with the used load.
    What kind of behavior does the device have? You could be more specific or provide me a graph of that behavior.

    Best Regards
    Jose Luis Figueroa
    Audio Applications Engineer | A-Team