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The bq27200 can't communication after program?

Suren Zhou
Intellectual 385 points
Other Parts Discussed in Thread: BQ27200

Hello Everyone,

 

I meet one case that bq27200 can't communication after program (I have eliminate the PCBA factor.) Could you please tell us the possible events cause the bq27200 no communication?

 

Thanks a lot.

Suren

  • 0
    TI__Genius 14985 points

    What hardware are you using to program the bq27200?

    A typical problem is if the rise and fall times of the 21V programming pulses do not meet the specifications in the datasheet.  If they are too fast then the high energy can be coupled to other EEPROM locations which you did not intend to write.  This can cause hidden factory trim data in EEPROM to become corrupted.  If you mess up certain locations you can affect the communication and could see a problem like you have seen.  You can also affect your accuracy if you mess up the factory trim data, even if you don't lost communication.  Therefore it is critical to measure your 21V programming pulse with an oscilloscope and ensure it meets the rise/fall time specifications.  If it does not meet the specifications you will need to shape the pulse with a simple filter.  The schematic on the bq27200 EVM shows an example programming circuit.

    This picture is of bq27x00EVM RevC and adds R19, R20, and C6.  The actual user guide (SLUU210) still shows RevB which is missing this filter, but the document will be updated.  The bq27x10EVM does show the latest schematic.

    You could also use this bq27x00 test/program system:

    http://focus.ti.com/docs/toolsw/folders/print/bq27x00-tester.html

  • 0 in reply to dMax
    Intellectual 385 points

    Dear dMax,

     

    Thanks for your feedback, i will verify the rais and fall time first.

    Whether we can read the trim data and confirm the trim data whether corrupted? Could you please provide the tool or the address of trim data to me?

    My email address: 57672208@qq.com

     

    Thanks a lot.

    Suren

  • 0 in reply to Suren Zhou
    Prodigy 65 points

    Hello Suran,

    If you have programmed other units that still communicate, you should verify that temperature, voltage, and current read correctly.  The trim values may be different for every unit, so reading trim data may not be productive.  The other issue is that both the trim data and EEPROM data are both subject to a poor lifetime if not written correctly, so it is important to write the data with slower rise and fall times..

    Bill J