Charge profile and cell-count flexibility
The MAX1645EEI handles 1 to 4 series cells at up to 18.4 V pack voltage, covering single-cell Li-ion portables through 4-series power-tool packs. Multi-chemistry support means Li-ion, Li-Poly, NiMH, and NiCd all charge from the same IC — the host selects the termination algorithm via the I²C/SMBus interface. Charge current is programmable up to 3 A max, set by an external sense resistor and pass transistor. The 28 V supply max gives margin above a 4-series Li-ion full-charge voltage of 16.8 V, and handles 24 V industrial rails without an external pre-regulator.
Housed in a 28-SSOP narrow-body (0.154-inch / 3.90 mm width) with a 0.0256-inch pitch. The small footprint saves board space in space-constrained portable designs.