ADAU1772 Codec got Reset at high volume if headset plug/unplug

Hi,

Used ADAU1772 codec on our board, using in Ain0/1 (Stereo input J2 jack) and HPOUTLP/HPOUTRP (Stereo output J8 jack), simple pass-through audio (DSP is not used).

Observed if plug/unplug headset at output stereo 3.5mm jack J8 with full volume (0dB gain), ADAU1772 codec got reset (register value goes to Reset default value).

If we do above at somewhat less volume (-5dB gain), plug/unplug works fine (no codec reset).

Also, observed if 0x0043 (OP_STAGE_CTRL) value 0x0 "Line Output mode", it is able to drive 16 ohm or 32 ohm headset without any issue.

I was expecting to drive 16/32 ohm headset only in "Headphone Output mode" (i.e. 0x0043=0x30). Audio output with 16/32 ohm headset has no difference/effect of 0x0043 = 0x0 (line out) or 0x30 (Headphone out).

Attached is our board schematic for reference.

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Thanks,

Ashvin

  • Analog Devices Support Team,

    Please help with your suggestions or comments.

  • +1
    •  Analog Employees 
    on Jul 6, 2021 7:30 PM

    Hello Ashvin,

    It seems like there is a spike that is getting through the power supply to the part that is great enough to trigger the internal reset circuits. I see that this is a separate board that is getting power through connector pins. Since the power supply is further way you probably need to increase the bulk capacitors on the AVDD and IOVDD pins to handle the surge locally. You currently have 10uf in those locations. I would try 47uf or even as high as 100uf to see if this will make a difference. 

    Then there is a possibility that PCB layout might be part of the problem. Generally you do not need to have the larger 10uf caps really close to the pins but there may be coupling from other traces. Is this a four layer PCB? If it is only two layers then the ground traces may also be part of the issue. If there is a long shared trace then you can get a spike on the ground that will reduce the voltage to the part and cause a reset. 

    Dave T

  • Hello Dave T,

    Thank you for the reply.

    We observed AVDD (VDD_3P3V) supply coming from the other carrier board has an issue, that power regulator output voltage dips from 3.3V to ~2.9V up on plug/unplug the headset (surge current) with input supply of 1.8V, if input supply of that power regulator is 3.3V, no issue. Also, we had a voltage supervisor on this codec board to monitor AVDD (VDD_3P3V) voltage for threshold of 3.07V before it release PD# (Reset of Codec).

    We lower the voltage supervisor threshold and see this issue resolved.

    Thanks,

    Ashvin