2-cell Li-ion charger with programmable current and safety timer
The BQ24006PWPR from Texas Instruments is a linear charger IC designed for a 2-cell series Li-ion battery pack. 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. The 20-HTSSOP with its exposed thermal pad needs a good copper pour and vias to keep the junction below the 125°C absolute maximum during a full charge cycle. 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.
Package and thermal management
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.
Lifecycle and sourcing posture
No pin-compatible second source or official replacement is listed in the TI documentation.