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Power an IC directly from a GPIO (MSP430G2444)?

Ryan Daly79
Prodigy 50 points

I've never seen applications where this is done, but the IC in question (ACS7222) only requires 9mA of power and has no "enable" pin.  So we're thinking of just supplying power to the IC directly from an MCU output.  That way we can disable the device by simply turning off its power.  However, I would like some input on possible (if any) issues that might come up.  Thoughts?

  • 0
    Guru 74080 points
    Hi Ryan!

    The datasheet has a graph that shows the voltage drop of the output over current consumption. This is not a constant value, so with higher consumption the device gets less voltage. I would not recommend to use a GPIO as a power pin. You could use an external P-FET if you want to completely remove the power. Or just use the enable pin if it acts as a power off. What is an ACS7222?

    Dennis
  • 0 in reply to Dennis Eichmann
    Prodigy 50 points
    Sorry, too many '2's in the part name. The ACS722 is a current transducer (Hall Effect type) with a 9mA operating current draw. Vcc is what determines the output voltage vs. current, so an unstable supply would be a big issue. I knew about the voltage drop, but I guess I was hoping it would not be significant at 9mA. I will look at the datasheet for this graph.
  • 0 in reply to Ryan Daly79
    Guru 74080 points

    If the output is ratiometric to the input, you should not do it. Or also feed this voltage into the ADC's reference input.

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