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INA226EVM Showing Strange Bus Voltage and Can't Disable Alerts

Simon Judge
Prodigy 20 points
Other Parts Discussed in Thread: INA226EVM

I have a new INA226EVM. I have configured as low side shunt as per the user guide, reading voltage across 10 ohm resistor with 1K ohm load. VBUS is regulated 5v. A multimeter shows a shunt voltage of 30mV. 

I have installed the software and it connected ok. I get the attached screen

The bus voltage says 81.92v ! Power is always 0W when I 'Read All Reg'. All the registers seem to be FFFF. The power jumper is set to INT. Also I can't change Stage 6 which always stays as shown above irrespective of what I set. I am also not sure the Alert should be green at the bottom of the screen.

Is this user error or a faulty card?

Thanks

Simon

  • 0
    TI__Genius 15760 points
    Hi Simon,

    Let me get an EVM and try this in the lab. I will get back to you soon.

    Mayrim
  • 0 in reply to Mayrim Verdejo
    TI__Genius 15760 points

    Hi Simon,

    I replicated your scenario and I don't see this error.  I noticed also that you are not adding Current LSB value in the GUI, that's why you don't see Current or Power Calculations results .  See my results below.

     

    Please test the EVM for me:

    1. Disconnect the shunt and load resistors.

    2. Make sure A0 and A1 have the jumpers connected to GND (both).

    3. Make sure VS jumper is connected to INT

    4. Apply 25mV or 30mV between Vin+ and Vin- (Simulated shunt voltage directly to the Vin pins)

    5. Apply 5V to Vbus

    6. Use the same settings as before in the GUI but please add the Current LSB value. ( Current LSB = Maximum Expected Current / 2^15)

    You should see similar results as below, if not then there might be something wrong with the setup or hardware. Please verify and let me know what you see.

  • 0 in reply to Mayrim Verdejo
    Prodigy 20 points

    Hi Mayrim 

    Thanks for looking into this. I have entered Current LSB but it's the same as before. I have also removed resistors and it's the same. Sorry I don't have bench PSU to supply 30mV.

    I have attached the screen with Current LSB set.

    I have also noticed that when I do 'Read All Reg' I get ERROR COMMUNICATING WITH DEVICE in red in the progress bar, it disappears very quickly and then it goes to blue as shown above. Is that normal?

    Here's what's in the Debug windows after I do a 'Read All Reg'...

    Command: I2C CH1 S 0x80 ACKS 0x00 ACKS S 0x81 ACKS R ACKM R ACKM P
    ACKS: 01 01 01
    Result: FF FF

    Command: I2C CH1 S 0x80 ACKS 0x01 ACKS S 0x81 ACKS R ACKM R ACKM P
    ACKS: 01 01 01
    Result: FF FF

    Command: I2C CH1 S 0x80 ACKS 0x02 ACKS S 0x81 ACKS R ACKM R ACKM P
    ACKS: 01 01 01
    Result: FF FF

    Command: I2C CH1 S 0x80 ACKS 0x03 ACKS S 0x81 ACKS R ACKM R ACKM P
    ACKS: 01 01 01
    Result: FF FF

    Command: I2C CH1 S 0x80 ACKS 0x04 ACKS S 0x81 ACKS R ACKM R ACKM P
    ACKS: 01 01 01
    Result: FF FF

    Command: I2C CH1 S 0x80 ACKS 0x05 ACKS S 0x81 ACKS R ACKM R ACKM P
    ACKS: 01 01 01
    Result: FF FF

    Command: I2C CH1 S 0x80 ACKS 0x06 ACKS S 0x81 ACKS R ACKM R ACKM P
    ACKS: 01 01 01
    Result: FF FF

    Command: I2C CH1 S 0x80 ACKS 0x07 ACKS S 0x81 ACKS R ACKM R ACKM P
    ACKS: 01 01 01
    Result: FF FF

    When I set Step 6, it always goes back to 'Shunt Voltage Over' when I do 'Read All Reg' Again. Here's what is in the Debug log:

    Command: I2C CH1 S 0x80 ACKS 0x6 ACKS 0x07 ACKS 0xFF ACKS P
    ACKS: 01 01 01 01
    Result: <none>

    Command: I2C CH1 S 0x80 ACKS 0x7 ACKS 0x00 ACKS 0x00 ACKS P
    ACKS: 01 01 01 01
    Result: <none>

    I have checked all the jumpers and they are already as you describe. LED D2 is also On.

    Thanks

    Simon

  • 0 in reply to Simon Judge
    TI__Genius 15760 points

    Hi Simon,

    I get the exact same results as you when the EVM is not connected to the USB DIG. There is error in communication. Did you verify all pins are connected properly (EVM and USB DIG?)

    Another thing you can try is switching the addresses. Move A0 and A1 jumpers to VS in the GUI and the EVM and verify if you can read.

    If you tried all this and your connections are good then it could be that the EVM is bad. Contact me so we can send a replacement.

    Regards,

    Mayrim