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INA219: Measured current too low

Franz Schellhase
Expert 3605 points

Part Number: INA219

Hi team,

Can you have a look at my customers technical request regarding INA219A?

We have installed 4 pieces of the INA219A as current sense monitor on our board. Unfortunately these ICs do not work as desired. We measure 0 Volt voltage although 5V are applied and the current value is much too low.

Thank you,

Franz

  • 0
    TI__Mastermind 32395 points

    Hello Franz,

    Has successful communication been established? Can customer read back default register values and write to device?

    Is customer trying to read back a bus voltage, shunt voltage or current value or both?

    Is the INA219 measuring positive or negative currents?

    Did they program the calibration register? If so, to what value and with what current LSB?

    What gain did they program the INA219 to?

    Can customer correctly read back the calibration register after writing to it to check if it is being programmed correctly?

    What is the level of current they are trying to sense? What is the INA219A incorrectly reporting?

    Can customer measure the input shunt/sense voltage while power applied to load?

    Thank you.

    Best,

    Peter

  • 0 in reply to Peter Iliya
    Prodigy 30 points

    Hello Franz, hello Peter,

    we have found the error :)

    In our application (LED display boards) there are different power supplies for VLogic and VLED necessary.
    The shunt resistor measures the current to the LED boards on the VLED rail.
    To ensure that the currents flow cleanly and to minimize possible interference from GND currents on the logic onto the control board, the two GNDs for VLED and Vlogic are not connected on the control board (on which the INA219 measures the currents).
    Instead of this, the two GNDs of VLED and VLogic are connected with a jumper at the two sepreate switching mode power supplies.
    This is the normal operating state of the LED display unit.
    Unfortunately the prototype was built up without this necessary GND bridge between the power supplies.
    This is the reason for the malfunction of the INA219A.
    After doing the GND bridge the function of the INA219A is given.

    Best regards,
    Oliver