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INA240: Offset after Power up

Christoph Keiner64843
Intellectual 270 points
Part Number: INA240

Hello,

i'm using INA240 for High-Side current measurement (DC-Supply Current, no PWM). 

The Devices will be factory Calibrated, but i found, that the Offset of the INA240 can change.

A: I found the behavior, that the Offset, which is in the Range of the datasheet,  is stable after Power up the 3.3V Supply and didn't change until the next Power up.

b: I also found, that the Offset more or less change between two different Values.

My Question is: can i rely on the Facts i found, or can the Offset (Assuming constant Temperature and environmental state) change arbitarily, even after Power up? 

regards,

Chris

  • 0
    TI__Mastermind 34250 points

    Hi Christoph,

    This is an issue with the commercial version of INA240, however it was already identified and fixed by the factory. What you received are probably residue units in the supply chain.

    Your observations are real:

    A - the offset is within data sheet limits. It is stable and will not change until next power up.

    B – The offset takes on one of two values. Both are within limits.

    Therefore, the offset will not change arbitrarily. After power up, it will be a constant and can be calibrated if desired.

    I don’t have a time line when we can be 100% sure such units will all be purged from supply channels. If this is an issue, as a temporarily solution you may use INA240-q1 automotive version where the offset will always take on just one value regardless of power cycle. 

    Regards, Guang

  • 0 in reply to Guang Zhou
    Prodigy 10 points
    i found it last year,but i have no time to find reasion,today i know it .