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INA226-Q1: INA226-Q1

Vel V
Prodigy 10 points
Part Number: INA226-Q1
Other Parts Discussed in Thread: INA226
I Hope you are doing well.
We are facing some issues with the I2C lines of INA226-Q1 IC. 
Kindly find the below image for reference. The below profile is captured across the Rshunt of 5mΩ but in our design we are using Rshunt of 0.5mΩ.
When we are getting the above profile across Rshunt of 0.5mΩ, we are able to see 100A charging and 84.3A discharging current through Rshunt.
Due to the above profile the following issues are observed
1.INA226 IC stops communicating with microcontroller..
2.SCL line is pulled to 3V3.
Kindly go through it and help us troubleshoot as early as possible.
  • 0
    TI__Mastermind 32395 points

    Hello valued engineer,

    So I understand correctly, when the following charge & discharge profile occurs in your system, the INA226 stops communicating with MCU corect?

    To help us debug as best as possible can you provide the following:

    1. Circuit schematic for the INA226? Especially the pull up resistors on SCL and SDA?

    2. I2C clock speed

    3. Oscilloscope shots of the supply voltage, the SDA and SCL pin voltages, and the input common-mode voltage (VCM) at IN+ and IN- pins during when the shown charge & discharge profile occurs?

    4. Once the problem occurs, are you able to re-establish any communication with INA226 or is device permanently non-responsive?

    We need to ensure that a system load change is not causing transient voltage spikes that could violate the Absolute Maximum ratings of the INA226. Additionally, we want to make sure all device pin voltages and grounds are stable during the profile shown.

    Best,

    Peter

  • 0 in reply to Peter Iliya
    Prodigy 10 points

    Hello Peter,

    Sorry for late reply.

    Kindly find the answers for your queries in orange color.

    So I understand correctly, when the following charge & discharge profile occurs in your system, the INA226 stops communicating with MCU corect?

    >>Yes,INA226 stops communicating and SCL line is pulled to 3V3 at that time.

    To help us debug as best as possible can you provide the following:

    1. Circuit schematic for the INA226? Especially the pull up resistors on SCL and SDA?

    >>Kindly find INA226 schematic below

    >>Pull up resistors are 2.21kohms

    2. I2C clock speed

    >> 100kbps

    3. Oscilloscope shots of the supply voltage, the SDA and SCL pin voltages, and the input common-mode voltage (VCM) at IN+ and IN- pins during when the shown charge & discharge profile occurs?

    >> Oscilloscope shots for

    Supply voltage: we are working on 3V3

    >>the SDA and SCL pin voltages

    >>The input common-mode voltage (VCM) at IN+ and IN- pins during when the shown charge & discharge profile occurs.

    4. Once the problem occurs, are you able to re-establish any communication with INA226 or is device permanently non-responsive?

    >>Yes, we can able to communicate with MCU after MCU hardware reset. During the fault as mentioned earlier SCL is pulled to 3V3 only.

    We need to ensure that a system load change is not causing transient voltage spikes that could violate the Absolute Maximum ratings of the INA226. Additionally, we want to make sure all device pin voltages and grounds are stable during the profile shown.

    >>YES, all device pin voltages and grounds are stable during the profile shown.

  • 0 in reply to Vel V
    TI__Mastermind 32395 points

    Hello Vel,

    Thank you for the information, but I believe there will need to be some more in order to prove what is happening.

    I assume this is a low-side sensing application (VCM=0V = GND) because you provide the same waveform/image for the input VCM and input differential/shunt voltage even though the first image was detailed as being the shunt voltage across a 5mΩ, even though the INA226 is sensing across a 0.5mΩ shunt.

    Unfortunately, we really need the measurement of IN+ to INA226_GND pin and IN- to INA226_GND pin during the problematic load profile. This is the only way to know what the true absolute input voltage is for the device and whether or not there is a VCM violation of VCM< -0.3V, which the waveform is actually indicating albeit for a short duration.

    The other piece of information needed is that the INA226 ground is actually stable during the profile. To know this we need the differential voltage measurement between INA226 ground and system/load ground. Impedance between these grounds can lead ground loops during rapid transient. Here is a document explaining this phenomenon. 

    https://www.ti.com/lit/an/sboa536/sboa536.pdf?ts=1641845114720&ref_url=https%253A%252F%252Fwww.ti.com%252Fsitesearch%252Fdocs%252Funiversalsearch.tsp%253FlangPref%253Den-US%2526searchTerm%253Dsboa536%2526nr%253D1

    Sincerely,

    Peter