BQ24295 Datasheet, PDF (26/45 Pages) Texas Instruments – I2C Controlled 3A Single Cell USB Charger

bq24295
SLUSBC1 – SEPTEMBER 2013
Voltage
5V
3.6V
3.4V
3.2V
3.18V
VBUS
SYS
BAT
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Current
3A
2.3A
2.0A
ISYS
ICHG
1.5A
IIN
1.0A
0.5A
-0.7A
DPM
DPM
Supplement
Figure 25. DPM Response
Supplement Mode
When the system voltage falls below the battery voltage, the BATFET turns on and the BATFET gate is
regulated the gate drive of BATFET so that the minimum BATFET V_DS stays at 30mV when the current is low.
This prevents oscillation from entering and exiting the supplement mode. As the discharge current increases, the
BATFET gate is regulated with a higher voltage to reduce R_DSON until the BATFET is in full conduction. At this
point onwards, the BATFET V_DS linearly increases with discharge current. Figure 26 shows the V-I curve of the
BATFET gate regulation operation. BATFET turns off to exit supplement mode when the battery is below battery
depletion threshold.
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
0
5 10 15 20 25 30 35 40 45 50 55
V(BAT-SYS) (mV)
Figure 26. BATFET V-I Curve
Battery Charging Management
The device charges 1-cell Li-Ion battery with up to 3A charge current for high capacity tablet battery. The 24mΩ
BATFET improves charging efficiency and minimizes the voltage drop during discharging.
Autonomous Charging Cycle
With battery charging enabled at POR (REG01[5:4]=01), the charger device complete a charging cycle without
host involvement. The device default charging parameters are listed in the following table.
26
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