Datasheet

bq24278
SLUSB04 –JUNE 2012 www.ti.com
These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam
during storage or handling to prevent electrostatic damage to the MOS gates.
DESCRIPTION (CONTINUED)
The power path management feature allows the bq24278 to power the system from a high efficiency DC to DC
converter while simultaneously and independently charging the battery. The charger monitors the battery current
at all times and reduces the charge current when the system load requires current above the input current limit.
This allows for proper charge termination and timer operation. The system voltage is regulated to the battery
voltage but will not drop below 3.5V. This minimum system voltage support enables the system to run with a
defective or absent battery pack and enables instant system turn-on even with a totally discharged battery or no
battery. The power-path management architecture also permits the battery to supplement the system current
requirements when the adapter cannot deliver the peak system currents. This enables the use of a smaller
adapter.
The battery is charged in three phases: conditioning, constant current and constant voltage. In all charge phases,
an internal control loop monitors the IC junction temperature and reduces the charge current if the internal
temperature threshold is exceeded. Additionally, the bq24278 offers a voltage-based battery pack thermistor
monitoring input (TS) that monitors battery temperature for safe charging .
ORDERING INFORMATION
NTC MONITORING JEITA MINIMUM SYSTEM
PART NUMBER IN OVP PACKAGE
(TS) COMPATIBLE VOLTAGE
bq24278YFFR 10.5 V Yes No 3.5 V WCSP
bq24278YFFT 10.5 V Yes No 3.5 V WCSP
bq24278RGER 10.5 V Yes No 3.5 V QFN
bq24278RGET 10.5 V Yes No 3.5 V QFN
ABSOLUTE MAXIMUM RATINGS
over operating free-air temperature range (unless otherwise noted)
(1)
MIN MAX UNIT
IN –2 20 V
PMID, BYP, BOOT –0.3 20 V
Pin voltage range (with respect to
SW –0.7 12 V
VSS)
SYS, BAT, BGATE, DRV, PG, CHG, CE, CD, TS, DRV_S, ILIM, ISET,
–0.3 7 V
VDPM
BOOT to SW –0.3 7 V
SW 4.5 A
Output current (continuous)
SYS 3.5 A
Input current (continuous) IN 2.75 A
Output sink current PG, CHG 10 mA
Operating free-air temperature range -40 85 °C
Junction temperature, T
J
-40 125 °C
Storage temperature, T
STG
–65 150 °C
Lead temperature (soldering, 10 s) 300 °C
(1) Stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. These are stress ratings
only, and functional operation of the device at these or any other conditions beyond those indicated under recommended operating
conditions is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. All voltage
values are with respect to the network ground terminal unless otherwise noted.
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