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BQ24195充电状态切换问题

Other Parts Discussed in Thread: BQ24195, BQ24195L

最近在用BQ24195做项目,发现如下问题;

1、在升压模式工作切换到充电模式后,STAT指示灯亮起,但是不能立马进入充电状态(电池端电流表无充电电流)

表现如下:CEpin 一直是拉低的状态,然后检测OTG被硬件拉低后关闭BOOST模式,使能CHARG BAT模式,这时候电池无充电电流;但是此时如果拔掉电池再插上或者单片机重启后(单片机启动过程中执行了初始化代码)就可以立即进入充电状态(电池端电流表出现充电电流);

2、在数据手册种看到使能充电条件如下:

A new charge cycle starts when the following conditions are valid:
Converter starts
• Battery charging is enabled by I2C register bit (REG01[5:4]) = 01 and CE is low
• No thermistor fault on TS1 and TS2
• No safety timer fault
• BATFET is not forced to turn off (REG07[5])

其中条件2 3 4 5均以满足,但是不清楚条件1如何启动?请求TI技术解答,谢谢!

以下是BQ24195初始化代码:


/* Set REG00 EN_HIZ = Disable; VINDPM = 4.2V; IINLIM = 3A */
BQ24195_Write_Register(0x00, 0x27); // 0 0 1 0 0 1 1 1

/* Set REG04 VREG = 4.2V; BATLOWV = 3.0V; VRECHG = 100mV */
BQ24195_Write_Register(0x04, 0xB2); // 1 0 1 1 0 0 1 0

/* Set REG02 ICHG = 2.048A; Reserved = 0; FORCE_20PCT = 0 */
BQ24195_Write_Register(0x02, 0x60); // 0 1 1 0 0 0 0 0

/* Set REG05 EN_TERM = 1; TERM_STAT = 0; WATCHDOG = Disable; EN_TIMER = Enable; CHG_TIMER = 5hours; Reserved = 0 */
BQ24195_Write_Register(0x05, 0x88); // 1 0 0 0 1 0 0 0

/* Set REG01 REGISTER RESET = 0; WATCHDOG TIMER RESET = 0; CHG_CONFIG = CHARGE BAT; SYS_MIN = 3.5V; Reserved = 0 */
BQ24195_Write_Register(0x01, 0x1B); // 0 0 0 1 1 0 1 1

  • Hi

        可能是操作顺序上的问题

        先将OTG pin HIGH and REG01[5:4] = 10 改过来,改为充电模式下设置。  再设置电流限制,CE拉低。

  • 谢谢您的解答;刚才仔细查看数据手册,发现了问题;数据手册种有这么一段话;

    8.3.3.5 Charging Safety Timer
    The bq24195L, bq24195 has safety timer to prevent extended charging cycle due to abnormal battery conditions.
    In default mode, the device keeps charging the battery with 5-hour fast charging safety timer regardless of
    REG05[2:1] default value. At the end of the 5 hours, the EN_HIZ (REG00[7]) is set to signal the buck converter
    stops and the system load is supplied by the battery. The EN_HIZ bit can be cleared to restart the buck
    converter.

    之所以重新配置就生效,很可能就是因为重写REG00寄存器时,重新给EN_HIZ位为0;重新启动了升压转换器;现在问题已解决!

  • 对于BQ24195这个料,一个忠告就是,各种状态切换或初始化时,最好都首先对HIZ进行置位,确保芯片得到确定的状态。