BQ24292I Datasheet, PDF (25/42 Pages) Texas Instruments – I2C Controlled 4.5A Single Cell USB/Adapter Charger With Narrow VDC Power Path Management and USB OTG

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bq24292i
SLUSBI4 – APRIL 2013
If the charger device is in DPM regulation or thermal regulation during charging, the actual charging current will
be less than the programmed value. In this case, termination is temporarily disabled and the charging safety
timer is counted at half the clock rate.
Regulation Voltage
(3.5V – 4.4V)
Fast Charge Current
(500mA-4020mA)
VBAT_LOWV (2.8V/3V)
Battery Voltage
Charge Current
VBAT_SHORT (2V)
IPRECHARGE (128mA-2048mA)
ITERMINATION (128mA-2048mA)
IBATSHORT (100mA)
Trickle Charge Pre-charge
Fast Charge and Voltage Regulation
Figure 28. Battery Charging Profile
Safety Timer
Expiration
Battery Path Impedance IR Compensation
To speed up the charging cycle, we would like to stay in constant current mode as long as possible. In real
system, the parasitic resistance, including routing, connector, MOSFETs and sense resistor in the battery pack,
may force the charger device to move from constant current loop to constant voltage loop too early, extending
the charge time.
The device allows the user to compensate for the parasitic resistance by increasing the voltage regulation set
point according to the actual charge current and the resistance. For safe operation, the user should set the
maximum allowed regulation voltage to REG06[4:2], and the minimum trace parasitic resistance (REG06[7:5]).
( ) ^V_{BATREG_ACTUAL} ^{= V}_{BATREG_I2C} ^{+ lower of I}_{CHRG_ACTUAL}^{× R}_COMP ^{and V}_CLAMP
(1)
Thermistor Qualification
The high capacity battery usually has two or more single cells in parallel. The device provides two TS pins to
monitor the thermistor (NTC) in each cell independently.
Cold/Hot Temperature Window
The device continuously monitors battery temperature by measuring the voltage between the TS pins and
ground, typically determined by a negative temperature coefficient thermistor and an external voltage divider. The
device compares this voltage against its internal thresholds to determine if charging is allowed. To initiate a
charge cycle, the battery temperature must be within the V_LTF to V_HTF thresholds. During the charge cycle the
battery temperature must be within the V_LTF to V_TCO thresholds, else the device suspends charging and waits
until the battery temperature is within the V_LTF to V_HTF range.
Copyright © 2013, Texas Instruments Incorporated
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