2-cell Li-ion charger with 1.2 A ceiling
The BQ24005PWP is a linear Li-ion charger IC from Texas Instruments designed specifically for 2-cell series packs. It delivers a constant charge current up to 1.2 A and terminates at a battery pack voltage of 8.4 V, which is the standard full-charge voltage for a 2S stack. The constant-current profile simplifies the charge algorithm — no need for external current-sense resistors or complex loop compensation.
Programmable current and timer for charge control
Charge current and a safety timer are programmable via external resistors, letting you set the charge rate to match the battery capacity and the timeout to prevent overcharge if termination is missed. The maximum supply voltage is 10 V, so the input rail must be regulated — a 5 V USB port alone won't reach the 8.4 V pack voltage; a boost converter or 9–10 V wall adapter is required.
Over-temperature protection and fault handling
The IC includes over-temperature fault protection that shuts down the charger if the die exceeds the thermal limit — a critical safeguard when charging at 1.2 A in a compact 20-HTSSOP footprint without active cooling. The battery chemistry is lithium ion, so it is not compatible with LiFePO4 or NiMH cells without a different termination voltage.