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DAC5681Z Current consumption @ 3V3 power supply

Other Parts Discussed in Thread: DAC5681Z, DAC5681EVM

Hello,

Please, ¿Which is the current consumption over 3V3 (AVDD) voltage for the DAC5681Z part number?

According to page 6 from the datasheet it should be 68mA (I_AVDD) but I have a current around 1A @ 3V3 in my PCB board.

I only apply the 1V8 and 3V3 voltages for the DAC chip.

I thing there is something brong but I have checked my layout several times and I have no shortcut con power supplies.

My schematic and layout is based on the DAC5681EVM schematic except I apply 3V3 volts at terminals 60 and 61 (part DAC5681Z is a single channel DAC):

Please, Any help will be great.

Regards
Ismael

  • Hi Ismael,

    1 A is definitely too much for the 3.3 V supply. My guess would be a short between the QFN pins and the powerpad. It's possible that too much solder was used on the powerpad and it has shorted out the 3.3 V supply. Have you tested for a short between the 3.3 V supply and GND? Use an ohm meter to check the impedance between these nets when the board is powered off.

    Regards,
    Matt Guibord 

  • Hello Matt,

    Thank you for your reply.

    The first check I did was to look for a short between AVDD (3V3) and GND and no short was found. In fact, the impedance between AVDD and GND is >3M Ohms. 

    Once I connect power supply (first 1V8V and then 3V3 as recommended in the dastasheet) current consumption goes up to 1.1A @3V3  and voltage from my power supply does not go down so current is not limiting. It seems something connected to configuration or whatever makes the DAC consume 1A @ 3V3.

    I have disassembled the balun at the output and the power consumption is still the same.

    If I do not aply 3V3 (AVDD) to pins 60 and 61 (Outputs from package for a a DAC with a second channel) the current consumption is the same.

    Thank you one more time for your help.
    Regards
    Ismael