4A synchronous buck charger for 1–3 cell Li-ion packs
The Texas Instruments BQ24172RGYR is a synchronous buck battery charger designed for one to three series Lithium Ion or Polymer cells, with a programmable constant-current charge up to 4 A and a maximum input supply of 17 V. The 24-VQFN with exposed pad (5.5x3.5 mm) pulls heat into the board plane, which matters when you're pushing 4 A into a deeply discharged pack and the die is dissipating several watts. On-chip fault protection covers over-current, over-temperature, and over-voltage — the scorch mark you'd otherwise find around a blown sense resistor or a cooked MOSFET gets caught before it happens.
Charge current programming and cell count flexibility
Charge current is constant and programmable via an external sense resistor and the ISET pin — you set the full-scale current with a resistor to ground, no I2C bus required. The 1 to 3 cell range means the battery pack voltage termination point shifts from 4.2 V (single cell) up to 12.6 V (three cells), all handled by the same IC with the appropriate resistor divider on the BAT pin. Operating temperature from -40 to 85°C covers most industrial and automotive cabin environments — outdoor telecom cabinets, portable instrumentation, and battery-backed UPS controllers are typical fits.