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BQ76PL455A-Q1: Usually have communication error when test on car

user5195153
Intellectual 450 points
Part Number: BQ76PL455A-Q1

Dears,

We use 6PCS bq76pl455a-Q1 series connection in one battery PACK,for HEV BMS application,daisy chain connect witih  Cap isolate.

When test on car,it is easily to get interference,make the uart communication error ,even when the car motor work,it will be worse,we need help to solve,thanks!

  • 0
    TI__Genius 10785 points

    Hi user5195153

    Did you follow our guidelines in the datasheet?

    You can check the section 8.1.2.

    Cap isolation is for same PCB.

    If not the cap +choke is the requirements.

    Roger

  • 0 in reply to Roger Hwang
    Prodigy 40 points

    Hi:

    Thanks so much for response.

    We use 6PCS bq76pl455a-Q1 series connection in same PCB.

    We  followed the section 8.1.2 of the datasheet. Cap isolation(2.2nf).

    Do you have  any Suggestions other than guidelines in the datasheet.

    Thanks!

  • 0 in reply to user5998122
    TI__Genius 10785 points

    Hi user5195153,

    Pl455A-Q1 is very mature device and we have many cars on the road now.

    It's hard for me to provide inputs.

    Do you think you can share schematic with us?

    I like to review it 1st.

    roger

  • 0 in reply to Roger Hwang
    Prodigy 40 points

    Thank you for reply! Schematic diagram is as follows. 6PCS bq76pl455a-Q1 series to connect 96 cells in same PCB,daisy chain connect witih  Cap isolate.

     

  • 0 in reply to user5998122
    TI__Mastermind 19795 points

    Hello,

    Based on your description of a UART communication error, the issue is likely from the isolation device used between the microcontroller and the PL455.

    Please probe both sides of the isolation device and see if there are any issues with slew-rate, pulse-width consistency, and frequency. Compare the input and output carefully to make sure no issues are being introduced on the lines.

    If you are seeing issues between the device communication lines, we recommend using the datasheet values for the COMM lines components.

    For the TVS diode, we recommend an extremely low capacitance diode, in order to not affect the rise-time of the communications. Our datsheet recommendation is the NXP PES5V0U1UA. Please probe the rise-time of the communication lines and make sure they are within datasheet spec. If you have an EVM available, comparing the rise-time to that will help visualizing the differences!

    Let me know if this solves your issue!

    Regards,

    Vince