2 A charge current — sizing the charge path
The BQ24105RHLRG4 is a multi-chemistry battery charger IC from the bqSWITCHER series, capable of delivering a programmable constant charge current up to 2 A. That 2 A ceiling sets the charge-time floor for a 1- to 3-series cell pack — a 2000 mAh cell charges in about an hour at full current, assuming the input supply and thermal design can sustain it. The current is set via an external resistor; the IC regulates the charge current to that programmed value until the battery reaches its voltage regulation threshold.
Supply and pack voltage — input and output limits
The maximum supply voltage is 16 V, and the battery pack voltage ceiling is 15.5 V. This means the charger can handle a 12 V adapter or a 5 V USB input (boosted internally) and charge up to three series Li-ion cells (12.6 V full) or a 4-cell LiFePO4 pack (14.4 V full). The 16 V input rating gives about 3 V of headroom above the pack voltage — enough for the internal buck converter to regulate without dropout.
Package and thermal — 20-VQFN with exposed pad
At 2 A charge current, the power loss in the internal FETs can reach 1-2 W depending on input-to-battery voltage differential; the pad-to-ambient thermal resistance is dominated by the PCB copper area.