BQ24133 Datasheet, PDF (16/35 Pages) Texas Instruments – 1.6-MHz Synchronous Switch-Mode Li-Ion and Li-Polymer Stand-Alone Battery Charger with Integrated MOSFETs and Power Path Selector

bq24133
SLUSAF7B – DECEMBER 2010 – REVISED MAY 2011
DETAILED DESCRIPTION
Regulation Voltage
V_RECH
I _CHRG
Precharge
Current
Regulation
Phase
Fastcharge Current
Regulation Phase
Fastcharge Voltage
Regulation Phase
Charge
Current
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Termination
V_LOWV
10% I_CHRG
Charge
Voltage
Precharge
Timer
Fast Charge Safety Timer
Figure 17. Typical Charging Profile
BATTERY VOLTAGE REGULATION
The bq24133 offers a high accuracy voltage regulator on for the charging voltage. The bq24133 uses CELL pin
to select number of cells with a fixed 4.2V/cell. Connecting CELL to AGND sets 1 cell output, floating CELL pin
sets 2 cell output, and connecting to VREF sets 3 cell output.
Table 2. bq24133 CELL Pin Settings
CELL PIN
AGND
Floating
VREF
VOLTAGE REGULATION
4.2V
8.4 V
12.6 V
BATTERY CURRENT REGULATION
The ISET input sets the maximum charging current. Battery current is sensed by current sensing resistor RSR
connected between SRP and SRN. The equation for charge current is:
I_CHARGE =
V_ISET
20 ´ R_SR
(1)
The valid input voltage range of ISET is up to 0.5V. With 10mΩ sense resistor, the maximum output current is
2.5A.
The charger is disabled when ISET pin voltage is below 40mV and is enabled when ISET pin voltage is above
120mV. For 10mΩ current sensing resistor, the minimum fast charge current must be higher than 600mA.
16
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