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Original question:

BQ25730: The BQ25730 cannot enter PTM mode

BQ25730: power on without battery

lei zhou1
Intellectual 260 points
Part Number: BQ25730
Other Parts Discussed in Thread: EV2400, TEST2,

Hi teams

    I have received BQ25730EVM, test diagram as below, I don't have EV2400 Communication Kit, so BQ25730EVM work in the default hardware configuration. I have do three test and CELL_BATPRESZ is configed as 3cell.

    Test1: When I connect battery,then power on external 12V, VSYS output voltage is equal to VBAT, I think it's normal operation.

    Test2: When I remove battery, and short JP4, then power on external 12V, VSYS output only 3.63V;

    Test3: When I remove battery, and open JP4, then power on external 12V, VSYS output 9.1V~9.35V when Iload<4A, VSYS and Iload test result as below table. This is the result I want, but CELL_BATPRESZ configuration is confict, so when battery is removed, CELL_BATPRESZ can still be set as 3CELL? If YES, after MCU power on, can I set BQ25730  VSYS output voltage>10.3V Current>6A through IIC interface?

    If CELL_BATPRESZ must be set to 0 when battery removal, how can I do let BQ25730 VSYS output voltage>10.3V, current>6A before MCU power on?

Test3 result:

Iload(A) VSYS(V) 　
0 9.35 　
1 9.21 　
2 9.19 　
3 9.17 　
4 9.16 max36.49W
5 7.24 　

Test diagram:

 

  • +1
    TI__Mastermind 33035 points

    HI, Lei,

    What you observed is normal behavior of the part. When battery is removed, you can keep it as 3S configuration. The charger will treat it as zero-voltage battery, and startup correctly. When you have I2C communication established, you can modify the registers and settings as you wish. 

    Hope this helps. 

    Regards,

    Tiger

  • 0 in reply to Tiger Zhou
    Intellectual 260 points

    Hi Tiger

        Your reply is very useful for me, sometimes our device battery removal, and load typical working voltage is 10.3V~12.3V, max load current is 6A, after MCU power up and  I2C communication established, can you tell me which register need to be configure and the register value is?

  • +1 in reply to lei zhou1
    TI__Mastermind 33035 points

    Hi Lei,

    I am glad it helps. The registers were loaded with default settings during power up. The charging operation could start with only two or three registers or commands. 

    1) disable watchdog timer, if charge current was not written periodically.

    2) set max charge voltage, if different from default value. 

    3) set charge current.

    For more details, see below user guide. 

    https://www.ti.com/tool/BQ25730EVM

    Regards,

    Tiger