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INA300: INA300 Hysteresis greater than expected.

Umar Khan
Prodigy 10 points
Part Number: INA300

Hello,

          I am currently using the INA300 for over current detection.  The limit resistor is set to 836 ohms and the sense resistor is 0.291 ohms. The hysteresis pin is floating so the hysteresis value should be 2 mV.

Given his information, the current threshold is set at 57.46 mA and due to hysteresis the transitions of the ALERT signal should occur at 63.44 mA and 49.69.

However I have observed that the transitions occur at 72 mA and 48 mA. 

The upper limit is far higher that what it should be.

Can you please let me know why this may be the case?

Thanks.

  • 0
    TI__Mastermind 26660 points

    Hello valued engineer,

    Would you please post a schematic and possibly a picture of the shunt resistor layout?

    I am looking over this in the mean time and will respond shortly.

    Best,

    Peter

  • 0
    TI__Mastermind 26660 points

    Hey Umar,

    You're correct that this range of tripping values should not be. To best determine this we definitely will need schematic and any basic layout information.

    I would recommend checking the double checking the system by also trying to measure shunt voltage with accurate >6 digit multimeter and double check how load current is being measured.

    Is there input filter?

    Is there any fluctuation in the input common-mode voltage over course of measurements?

    Does the device have a stable ground plane?

    Sincerely,

    Peter