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TI-SCB: TI-SCB IC Heat Up and INA226EVM Alert is ON

Choon Seang Tan
Prodigy 30 points
Part Number: TI-SCB
Other Parts Discussed in Thread: INA226EVM, INA226

Tool/software:

Dear TI,

I found that one of TI-SCB (mark with D) very hot at the big IC when connecting to PC/USB hub.

Same setup, another TI-SCB (mark with B) do not feel the heat when connected to same PC/USB hub.

Beside, the Alert LED D2 INA226EVM (C) is also light up when connect to TI-SCB (D). Either of the INA226EVM connected to TI-SCB (D) also will trigger the Alert LED D2.

Serial communication to both TI-SCB currently is normal,

I believe it is not normal when the TI-SCB big IC at high temperature when connected to PC (even without connect to any EVM sensor board), kindly advise was the TI-SCB (D) is faulty or else how to debug so that the IC wont be at high temperature.

  • 0
    TI__Mastermind 26345 points

    Hello Choon-Seang,

    This does seem very odd. What Alert settings did you program for the INA226? If you didn't set any alert settings, then there could be a short or other hardware error pulling the power to GND, which may explain the heating. If that is the case, you may be able to do a short test with the PCB off and see if the resistance between power and GND is low.

    Regards,

    Mitch

  • 0 in reply to Mitch M
    Prodigy 30 points

    Hi Mitch, 

    I did not program the alert setting, both of the pair of TI-SCB + INA226EVM are using the same register as below step and start perform measure to get bus voltage and shunt voltage

    1. initialize the INA226EVM - pointer address "00" with 8000h

    2. configure pointer address "00" with 4b7fh

    3. take measurement from bus and shunt voltage continuously

    I use a DMM and found below terminal and components have low resistance,

    1. Master to Slave Connector Pin 4 and Pin 6 ~ 33 ohm

    2. C15, C16, C28, C33, C12, C20, C36, C41, C10, C39, C40, C22 ~ all around 33 ohm, open load if measure capacitance

    3. C18 ~ 88 ohm, open load if measure capacitance

  • 0 in reply to Choon Seang Tan
    TI__Mastermind 26345 points

    Hello Choon-Seang,

    Does the SCB still get hot when there is no EVM connected? Since you are not configuring the ALERT, there is likely a hardware problem causing the ALERT to pull down. Can you try removing the ALERT BUS jumper and see if there is still an issue? (My guess is that the ALERT will not turn on, but the heating issue will still be there)

    Choon Seang Tan said:
    Master to Slave Connector Pin 4 and Pin 6 ~ 33 ohm

    This does look concerning, what is the resistance for the same pins on the SCB that does not heat up?

    Can you also check the resistance on the connector between Pin 8 and GND on both SCBs?

    Regards,

    Mitch

  • 0 in reply to Mitch M
    Prodigy 30 points

    Hello Mitch,

    Yes, SCB also get hot even no EVM was connected.

    As your guess, when Alert Bus jumper pull out, Alert LED will not light up and SCB still have heating issue.

    Resistance between pin 4 and pin 6

    >bad SCB, ~ 33 ohm

    >Good SCB, ~ 18.8k ohm

    resistance pin 2 and pin 4, ~ 15,6k ohm (same for both SCB)

    resistance between pin2 and pin 8,

    > bad SCB, 2 ohm shorted,

    > good SCB, ~ 324k ohm

  • 0 in reply to Choon Seang Tan
    TI__Mastermind 26345 points

    Hello Choon-Seang,

    In that case it definitely looks like there is a short on the bad SCB. Not sure what channel you bought it from, but you can try to see if it is returnable or refundable. 

    Regards,

    Mitch

  • 0 in reply to Mitch M
    Prodigy 30 points

    Hi Mitch,

    We brought from Mouser Electronic, will ask them to have replacement.

    Thank you.