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INA228AQDGSRQ1-IIC Communication issue

ms zhang
Prodigy 10 points
Other Parts Discussed in Thread: INA228

Dear,

I used MCU to communication with TI-INA228.

But it looks the TI chip do NOT response .

The iic oscilloscope and sche diagram picture as attachment.

Pls give some feedbal ASAP . 

  • 0
    TI__Expert 7680 points

    Hi Zhang,

    From your scope measurement is seems like the logic LOW for the SCL line only goes down to 0.725V with respect to GND.

    From the data sheet, the Max voltage on the SCL/SDA lines for the device to detect a logic LOW is 0.4V with respect to ground. 

    ΔY is only 4.5V when it should be closer to 5V according to the schematic. 

    If this is the case then INA228 will not be able to identify that the SCL line has transitioned to a logic LOW, thus no I2C data will be clocked and the device NACKS on the acknowledge bit. 

    Is the system properly grounded? Is ISO_5V0 referenced to a different ground from ISO_GND? Is ISO_GND the same ground as your MCU GND?

    From the scope shot it doesn't appear to be a timing issue, so verifying the ground connections is worth taking a look into to see if it fixes the issue. 

    Best Regards,

    Angel