BQ24295 Datasheet, PDF (27/45 Pages) Texas Instruments – I2C Controlled 3A Single Cell USB Charger

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SLUSBC1 – SEPTEMBER 2013
Table 4. Charging Parameter Default Setting
DEFAULT MODE
Charging Voltage
Charging Current
Pre-charge Current
Termination Current
Temperature Profile
Safety Timer
bq24295
4.208 V
1.024A
256 mA
256 mA
Hot/Cold
12 hours⁽¹⁾
(1) See section Charging Safety Timer for more information.
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 TS
• No safety timer fault
• BATFET is not forced to turn off (REG07[5])
The charger device automatically terminates the charging cycle when the charging current is below termination
threshold and charge voltage is above recharge threshold. When a full battery voltage is discharged below
recharge threshold (REG04[0]), the device automatically starts another charging cycle.After the charge done,
either toggle /CE pin or REG01[5:4] will initiate a new charging cycle.
The STAT output indicates the charging status of charging (LOW), charging complete or charge disable (HIGH)
or charging fault (Blinking). The status register REG08[5:4] indicates the different charging phases: 00-charging
disable, 01-precharge, 10-fast charge (constant current) and constant voltage mode, 11-charging done. Once a
charging cycle is complete, an INT is asserted to notify the host.
The host can always control the charging operation and optimize the charging parameters by writing to the
registers through I²C.
Battery Charging Profile
The device charges the battery in three phases: preconditioning, constant current and constant voltage. At the
beginning of a charging cycle, the device checks the battery voltage and applies current.
VBAT
V_BAT < V_SHORT
(Typical 2V)
V_SHORT ≤ V_BAT < V_BATLOWV
(Typical 2V ≤ V_BAT < 3V)
V_BAT ≥ V_BATLOWV
(Typical V_BAT ≥ 3V)
Table 5. Charging Current Setting
CHARGING CURRENT
REG DEFAULT SETTING
100mA
–
REG03[7:4]
256mA
REG02[7:2]
2048mA
REG08[5:4]
01
01
10
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