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TAS6584-Q1: TAS6584 Chips Burning Out on Power-up

Tom G.
Prodigy 60 points
Part Number: TAS6584-Q1

Tool/software:

Starting late June, we've been encountering issues where some TAS6584 chips are burning out spectacularly immediately upon power up and supplying it with 36V PVDD, 36V VBAT, 3.3V DVDD. It would leave the board burnt and charred. We also noticed that the impedance between the PVDD and GND pins is quite low (<50 Ohm) on our most recent batch of TAS chips.

Has anyone else encountered such a scenario?

  • 0
    TI__Mastermind 49740 points

    Hi Tom

    Let's capture the detailed power on sequence first. Including PVDD/VBAT, DVDD, STBY pin, and PD pin. 

    Did any I2C script been written into the IC? Please kindly provide the settings.

    And could you also share schematic and PCB? 

  • 0 in reply to Shadow He
    Prodigy 60 points

    Some units are failing immediately upon bootup so I doubt there's any register settings that could be causing this. Others will boot up without any issue but after power off and then fail when they're powered back on. Is there a particular power-on or power-off sequence that could trigger this kind of failure mode.

    I cannot share the full schematic and PCB without an NDA. But I can share just the relevant section if that helps?


    In case it helps, here's a snippet of our python script used on initialization of the TAS chips:

    self._register_map.set_property(self.address, "CLEAR_FAULT", 1)

    # Enable TDM Mode
    self._register_map.set_property(self.address, "TDM_EN", 1)

    # Set audio interface format to TMP/DSP
    self._register_map.set_property(self.address, "AFMT", 1)

    # Set word length to 32 bits
    self._register_map.set_property(self.address, "I2S_WL_1", 3)

    # Add appropriate offset for device
    tdm_shift = self.__calculate_tdm_shift()
    tdm_shift_msb = tdm_shift >> 8
    tdm_shift_lsb = tdm_shift & 0xFF
    logging.info(
    "Setting TAS {} tdm shift to {}".format(self.device_number, tdm_shift)
    )
    self._register_map.set_property(
    self.address, "REG_I2S_SHIFT1_MSB", tdm_shift_msb
    )
    self._register_map.set_property(
    self.address, "REG_I2S_SHIFT1_LSB", tdm_shift_lsb
    )

    # If the FSYNC pulse is shorter than 8 x SCLK
    self._register_map.set_property(self.address, "FS_PULSE_WIDTH", 1)

    # Set switching frequency to 440 KHz
    self._register_map.set_property(self.address, "FSW_SELECT", 1)

    # Set modulation scheme to 1SPW
    self._register_map.set_property(self.address, "MODULATION", 1)
    channels = range(1, 5)
    self.set_deep_sleep(channels)
    for channel in channels:
    self._register_map.set_property(
    self.address,
    "CH{}_AVOLUME".format(channel),
    int(Tas6584.ANALOG_DB * -4),
    )

    # Automatic DC Load Diagnostics disabled
    # According to TI, this is safe to do because the system has overcurrent
    self._register_map.set_property(
    self.address, "LDG_BYPASS", 0
    )
    self._register_map.set_property(self.address, "CLEAR_FAULT", 1)
  • 0 in reply to Tom G.
    TI__Mastermind 49740 points

    Hi Tom

    Tom G. said:
    Is there a particular power-on or power-off sequence that could trigger this kind of failure mode.

    Power on usually not too much to worry about. But Power off, would need to take care of.

    As datasheet requested below.

    Tom G. said:
    But I can share just the relevant section if that helps?

    Sure, only the TAS6584 part would be fine. The incorrect PVDD decoupling, will also increase the failure possibility.