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TAS5414A CP/AVDD Undervoltage

Other Parts Discussed in Thread: TAS5414A

I'm using the TAS5414A with a circuit identical to the typical application schematic provided in the datasheet. It's being powered by a 12V DC source.

I2C Fault Register 1(0x00) returns 0x30 and External status register 1(0x04) returns 0xc0. Both seem to indicate a AVDD undervoltage and Charge-pump undervoltage scenario. Voltage at the CP pin is 12.57V while the voltage at the A_BYP pin is 0.11V. I believe AVDD is generated internally, so is this a fault with the IC? Is there some documentation I can read to further diagnose and fix this issue if possible?

A_BYP and D_BYP both have 100nF capacitors to GND. CP is connected to PVDD with a 1uF capacitor in between and CPC_TOP and CPC_BOT also have a 1uF capacitor in between.

Voltage at other relevant pins:

PVDD - 12.94V

CP - 12.57V

CPC_TOP - 12.51V

CPC_BOT - 0.11V

D_BYP - 3.44V

A_BYP - 0.11V

Thanks,

Bharath

  • Bharath,

    The fault indication in register 0x00 is correct.  The voltage on the CP should be over 20Vdc in the case.  The CPC_BOT pin should have a switching waveform with a frequency equal to Fsw (417kHz is the default setting).  With a voltage of 0.11Vdc on the CPC_BOT, I suspect this is the issue.  Please check your pcb layout for proper connections and for a proper solder connection to the CPC_BOT pin.  The A_BYP will not have a voltage until the CP has a proper voltage.

  • Gregg,

    Thanks a lot for getting back. I've double checked to ensure that CPC_BOT and CPC_TOP have no other traces but to the 1uF capacitor that connects them. Similarly CP is only connected to the 1uF capacitor to PVDD. I've also tried replacing the capacitors to see if that helps, but the same fault is reported.
    Now, I get a voltage of -0.03V on CPC_BOT. CP is at 11.99V while PVDD is at 12.5V. I don't have an oscilloscope with me at the moment so I can't look at the waveform.

    I'll also try a combination of another board and another TAS5414A IC to see if the issue is specific to this chip or board.

    Once again, appreciate your assistance.

    Bharath