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Cannot charge with BQ24735EVM-710

Other Parts Discussed in Thread: BQ24735

Dear support team,

Now I am using a MCU to connect with your board(BQ24735EVM-710) by I2C.

Set up on My Board:

J1: connect to 22V

J2(BAT-GND): connect to my battery

SDA: connect to SDA of MCU

SCL : connect to SCL of MCU

3V3: connect to 3v3 of MCU

I can get DeviceID and ManufactureID. I can read and write CHARGE_OPTION(0x12)

But it doen't charge. (bit[0] of CHARGE_OPTION REG is 0)

I try many ways, but it doesn't help

Please help me



  • For more information.
    I set: 0xF952 to CHARGE_OPTION reg
    I set: 0x4000 to CHARGE_VOL reg
    I set: 0x1000 to CHARGE_CURRENT reg
  • Hi Tam,

    Did you mean that your MCU communicates with the EVM using SMBus? The BQ24735 uses an SMBus interface, not I2C.

    Your adapter voltage is 22 V, and from looking at your register settings, it looks like you're trying to set the battery charge voltage to 16.384 V and the charge current to 4.096 A. What kind of battery are you connecting, and are the previous steps in the User's Guide procedure (Sections 2.4.1 and 2.4.2) working correctly?

    Best Regards,
  • Dear Angelo,

    Thanks for your hints.

    We can use MCU to communicate with BQ24735 by using I2C. Just follow 

    Notes: SLAVE ADDRESS = 0x12

    For example: 

    To Get Device ID: 

       1. Write: 0xFF (Device_ID_COMMAND) to Slave Address (0x12)

       2. Read data from slave address(0x12)

    I followed this guide, every thing is oke, But my battery is broken, I replace new battery, It works.