2-cell Li-ion charger with programmable current and safety timer
It regulates the charge voltage to 8.4V and delivers a constant charging current programmable up to 1.2A. A programmable safety timer prevents overcharging if the termination current is never reached, and the built-in over-temperature protection shuts down the pass element if the die exceeds the safe junction limit.
Charge current and pack voltage — sizing the power path
The 1.2A maximum charge current sets the heat dissipation floor in the linear pass element. At 1.2A with a 5V input and an 8.4V pack, the dropout across the pass transistor is about 1.6V, so the thermal power is roughly 1.9W. For faster charging than 1.2A, you would need a switching charger — this part is a linear regulator, so the current limit is thermal, not electrical. The 8.4V full-charge target matches the standard termination voltage for two Li-ion cells in series. If the pack chemistry is LiFePO4 (3.6V per cell nominal) or the cell count is different, this charger will overvoltage the battery. Confirm the pack configuration before committing the BOM line.
Surface-mount assembly requires a solder-paste stencil aperture covering at least 50% of the pad area for reliable solder-joint formation and heat transfer.