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SN74AUP2G08: SN74AUP series parts consume more power than expected

Todd Shelton
Prodigy 100 points
Part Number: SN74AUP2G08

I am using multiple parts from the SN74AUP family to implement some logic that is powered from a battery source. I have included two SN74AUP2G08DCUR, two SN74AUP2G32DCUR, and one SN74AUP3G04DCUR in my design. I had expected the total current draw for the five devices to be less that 5uA since the datasheet indicated that the static-power consumption was 0.9uA maximum. The circuit does drive a single load that requires ~3.5uA of current, and with the implemented logic, I was expecting a total current draw for this circuit to be less that 10uA. Using a series resistor to measure the current, I am seeing ~35uA of current draw for this circuit. I have confirmed this current draw on two different implementations. I have also confirmed that the input signals are not transitioning. I have attached a copy of my schematic implementation. Can you provide additional support in idnetifying why I am observing a higher than expected current draw from these devices? Battery voltage is 3.61V. Is this VCC voltage the source of my extra current consumption? With a battery voltage of 3.54V, I still measure a current draw of 32.5uA.

I can provide a schematic for the E2E representative, but I would rather not post it publicly.

Thanks,

Todd

  • 0
    TI__Guru* 96591 points
    Hi Todd,
    Can you send me your design via email? If you have a layout as well it would be helpful.

    My email is Emrys (at) ti.com
  • 0 in reply to Emrys Maier
    TI__Guru* 96591 points
    Hey Todd,
    Thanks for sending over the schematic.

    I don't see any problems with your design. You mention that you expect 1uA per device for supply current, but that's the _absolute maximum_ rating. You shouldn't be seeing even half that for typical operation (abs max at 25C is 500nA). It's likely that there's something else going on in the system - as you mentioned, something down-stream from the AUP device could be drawing current from the output of the AUP devices, and that would add to the Icc numbers under normal operation.

    Same thing for leakage -- these devices typically have leakage in the very low nA range. If you're seeing more than 1uA of leakage, there's probably something else going on. I've seen this kind of thing happen from residual flux on boards or other debris.

    If you find that there's no possible other culprit, you can start a Failure Analysis return (FA) with your distributor to send the devices back to us for analysis. They should definitely not be eating that much power in static operation.