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INA212: Power Consumption with no V+ Applied

Andrew Kuikman
Prodigy 130 points
Part Number: INA212

Hi,

We have designed in the INA212 into our system, and are noticing the devices are drawing power when we have V+ grounded.

Essentially we are powering the device V+ through a 3.3V GPIO, so are able to ground V+ when needed. REF always has 1.5VDC applied to it. IN+ and IN- always have 0V/3.3V toggling. Do we expect the INA212 to consume power when V+ is grounded, and there is a voltage on VREF?

I have physically removed the 2 INA212 devices from our boards, and can observe a drop in power of ~16mW when they are removed. Without knowledge of the internal workings of the devices, are the devices expected to draw power with V+ set to 0V, and REF set to 1.5VDC? Any help you can offer would be greatly appreciated.

Thanks,

Andrew

  • 0
    TI__Mastermind 29740 points

    Hi Andrew,

    The device does draw power with V+ set to 0V. Please see this typical curve in the data sheet:

    The 16mW number is a bit high. To reconcile the difference, you may want to measure the input bias currents drawn by INA212. They should align with above curve.

    Regards, Guang

  • 0 in reply to Guang Zhou
    Prodigy 130 points

    Hi Guang,

    Thank you for the quick reply. I did see that chart in the DS, but unfortunately it does not explain our issue. The devices on our board each look to be drawing ~2.5mA each with V+ set to 0V. The output is connected directly to an ADC input, so I dont expect there to be any issue there.

    I will try to modify our boards to monitor the input bias current. Are there any other potential causes for the high current (potentially from REF)? 2.5mA is very high to be input bias current.

    Thanks,

    Andrew

  • 0 in reply to Andrew Kuikman
    TI__Mastermind 29740 points

    Hi Andrew,

    The device shouldn’t draw ~2.5mA under any circumstance, REF pin voltage shouldn’t matter. Something is obviously wrong. I’m equally curious to learn what caused this phenomenon.

    Are the devices still working normally if power to them is restored?

    You may also monitor the Vs pin voltage.

    Regards, Guang