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INA228: VBUS reading gets stuck

Pelle Lund
Prodigy 40 points
Part Number: INA228

I'm having a PCB where I'm having a few INA228.

Some of the INA's are getting stuck on the same VBUS voltage. Reading is good for a few minutes but later it's just giving the same value all over. Between different runs it happens with different INA's so it's not the same ones every time. Current and vshunt looks fine even though the VBUS is stuck.

Any idea what can cause this?

  • 0
    TI__Expert 6602 points

    Hi Pelle, 

    What type of variance are you expecting in your VBUS measurement? Is it possible that the VBUS levels seem to level out and really consistent after a while? If you could share any information that would help me troubleshoot, that would be great. Any schematic, or register values would help. At first glance however, this seems like it may be a system level issue. 

    Best,

    Mohamed 

  • 0 in reply to Mohamed Hamida
    Prodigy 40 points

    The node VBUS is a stepping function which is in this case stepping from 0v -> 0.6v -> 1v -> 1.5v -> 2v. The INA's that get stuck is stuck on a value around 0.6v, they're stuck at different voltage levels so its different every time, but always around 0.6v. This tells me it get stuck between 5-60 seconds from the initial turn on.

    Can provide register outputs and schematic tomorrow.

  • 0 in reply to Pelle Lund
    TI__Expert 6602 points

    Is every instance of the current sensor getting stuck or are there just a few bad units? 

  • 0 in reply to Mohamed Hamida
    Prodigy 40 points

    There is a few units, maybe 2-3 out of 24 at every run. Although the bad readings is not the same units between runs so it's not the unit itself. I mean the current and vshunt is fine, is updating and giving me reasonable values, but vbus is stuck. First i read current, then vbus, then vshunt, so i guess the I2C communication is fine as well?

    Wonder what can cause this error that this register seems to lock while the other registers not.

  • 0 in reply to Pelle Lund
    TI__Expert 6602 points

    Hi Pelle, 

    Do you mind supplying me with the register readouts at the time of the issue? Also, to verify the I2C communication you could attach a scope to the I2C SDA and SCL lines and verify the values are what you expect. 

    Best,

    Mohamed