Multi-chemistry charger in an 8-pin SOIC
The Texas Instruments BQ2000TSN-B5TR is a multi-chemistry battery charger controller that handles 1 to 4 cells in series, supporting NiCd, NiMH, Li-Ion, and Li-Pol chemistries without needing a different IC for each cell type. Charging current is constant and programmable via an external sense resistor, and the device also lets you set the charge termination voltage and a safety timer — three programmable parameters that give you control over the charge profile without firmware.
Supply headroom and temperature range
Maximum supply voltage is 6 V, so the input rail must stay below that — a 5 V USB bus or a regulated 5 V wall adapter fits, but a raw 12 V supply needs a pre-regulator.