Single-cell Li-Ion charger with USB input and 1.5A ceiling
Charge current and programmable features — sizing the BOM
The 1.5A maximum charge current sets the thermal design target: at full current the 16-VQFN exposed pad must be soldered to a sufficient copper area to keep junction temperature within the 0°C to 125°C operating range. The charge current is constant and programmable, meaning an external resistor sets the rate — the BOM should include the sense resistor and a programming resistor, both 1% tolerance for repeatability. The timer is also programmable, which allows setting a safety timeout for charge termination independent of the current taper.
Package and thermal — layout consideration
The exposed pad (3x3 mm) is the primary thermal path. The layout must stitch vias from the pad to an inner ground plane to spread heat; without that, junction temperature rises quickly above 1A continuous charge.
The BQ24079TRGTR is an active product per TI's lifecycle status. It is ROHS3 compliant.