Linear charger with I²C control — BOM-fit for single-cell portable gear
The Texas Instruments BQ25125YFPT is a multi-chemistry linear battery charger IC for single-cell packs, packaged in a 25-bump DSBGA. It handles a 20V maximum input supply and delivers up to 300mA charge current, programmable via I²C. The wide input tolerance means it can sit directly on a 5V USB bus or a 12V rail without a front-end buck regulator — a BOM simplification for space-constrained designs like wearables, hearing aids, or medical patches.
300mA charge ceiling — sizing the charge time and thermal budget
At 300mA max, this part is sized for small-capacity cells. A 200mAh cell charges in roughly 40 minutes at the full rate. The linear.
I²C programmability — dynamic charge profiles without resistor swaps
Charge current and voltage are set over I²C, not by pin-strap resistors. That lets firmware adjust the charge profile on the fly — taper current during thermal throttling, switch between Li-ion and LiFePO4 termination voltages, or reduce current when the system load is high. The interface also supports reading fault and status registers, which simplifies system-level charge management without an extra ADC pin.
Protection set — over-voltage and short-circuit
Built-in fault protection covers over-voltage on the input and output short-circuit conditions. For a single-cell charger, the over-voltage lockout prevents damage from a mis-wired or faulty adapter, and the short-circuit protection keeps the battery path safe during assembly or a cell fault. No external protection FETs needed for basic safeguarding.