Multi-chemistry charge control in an 8-pin TSSOP
The Texas Instruments BQ24401PWR is a multi-chemistry battery charge controller that handles NiCd, NiMH, and Li-Ion chemistries through an external pass element. The charge algorithm is timer-based—you set the charge time with a single capacitor, and the chip terminates when the timer expires. No delta-V or dT/dt sensing needed, which keeps the BOM simple for cost-sensitive chargers in consumer electronics, portable instruments, and backup power systems.
If your charger sits in a 40°C ambient enclosure with self-heating from the pass transistor, you need to check the junction temperature derating; the controller itself stays within spec, but the external MOSFET and sense resistor will dominate the thermal budget.
Package and supply voltage realities
The maximum supply voltage is 6 V, so this part runs off a 5 V rail or a single-cell Li-Ion directly—no need for a separate regulator. The 8-TSSOP is a small outline, but the pin pitch is 0.65 mm, so a standard two-layer board with 0.3 mm traces can route it without a via farm.
For dual-sourcing planning, there is no published pin-compatible second source; the BQ24401 family is a Texas Instruments proprietary design, so any alternate would require a PCB spin or a different charge-control architecture.