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BQ76PL536-Q1: Communication problem

Eiz Po
Prodigy 30 points
Part Number: BQ76PL536-Q1
Other Parts Discussed in Thread: BQ76PL536A-Q1

Hello,

I am using BQ76PL536-Q1 in my project. I was successfully started communication with it. However after few minutes BQ76PL536-Q1 stopped responding. After restart or voltage removal from IC, I was again able to communicate with it, then again, it stopped, seemingly completely randomly. I then started measuring regulator output voltage and found some strange patterns. When it communicates with controller LDOD voltage is 4,7,REG50 is 5 V, VREF is 2,5V. But when its its not working then LDOD is 2,3, REG50 is somewhere between 1V and 3V, VREF is from 0.5V to 1.4V.

I am using STM32 microcontroller  to communicate with BQ76PL536-Q1, but STM32 communication voltage is 3.3V. Could that be the cause of the problem? 

  • 0
    TI__Genius 10785 points
    I think you are working with bq76pl536A-Q1, right?

    Remember, you can use either 3.3V or 5V communication voltage but PL536A-Q1
    SDO is 5V output so you need to consider for your design.

    Questions/comments for you.
    1. Are you using TI evm or your own design.
    2. Does IC works okay if you remove the cell and connect back?
    3. LDOD 2.3V is definitely not going to work. IC is not working properly.
    4. Do you think I can review the schematic if you are using your own schematic?
    5. I'd like to know what you did to device to stop working. Did you change the cell voltage, unplug cells, debugging on PCB and etc... It's little bit hard to digest that PL536A-Q1 just stop working. I want to understand so I can support you.

    You can invite me as your friend privately if you don't want to share the schematic to public.
  • 0 in reply to Roger Hwang
    Prodigy 30 points
    Thank you for your answer, but it's seems that I have found the problem. Today I again ran some tests, because it was not working, when I noticed that there was some type of fluid under the chip. I think it might be the flux I used for soldering . I then measured resistance of the flux and the resistance was 500k for 1cm. Flux was shorting pins. Afterwards I heated the chip so the flux vaporizes and it seems to have resolved the initial problem and now the chips works as expected.
  • 0 in reply to Eiz Po
    TI__Genius 10785 points
    glad that you fixed the problem..