The BQ24157SYFFT is a single-cell Lithium Ion/Polymer battery charger IC from Texas Instruments. It delivers a programmable charge current up to 1.25 A to a battery pack voltage of 4.44 V max. The I²C interface lets the system microcontroller set the charge current and termination voltage without external resistors, saving board space.
1.25 A charge current — thermal and layout impact
At the 1.25 A maximum charge current, the power dissipation in the 20-DSBGA package becomes the limiting factor. The 0.5 mm pitch BGA has no exposed thermal pad; heat conducts through the solder balls and the top-layer copper. The constant-current charge phase is programmable via I²C, so the charge current can be reduced to stay within the thermal budget of a given PCB layout.
The part is ROHS3 compliant. For volume requirements, the Tape & Reel (TR) packaging option is standard; Cut Tape (CT) is available for prototyping.
Supply rail and protection features
The IC operates from a supply voltage up to 6 V and includes over-temperature and over-voltage fault protection. The -30°C to 85°C ambient temperature range covers industrial and consumer portable applications.