Single-cell Li-Ion charger with USB input
The BQ24230RGTT is a linear charger IC for single-cell Lithium-Ion batteries, designed to draw power from a USB port. Its 500 mA maximum charge current suits portable devices where charge time is balanced against thermal budget in a small 3x3 mm QFN. The part integrates fault protection against over-temperature, over-voltage, reverse current, and short-circuit conditions — covering the common failure modes when a USB cable is hot-plugged or the battery is reversed.
Supply and charge-current boundaries
Maximum supply voltage is 6.4V — typical USB VBUS is 5V, but the 6.4V ceiling gives headroom for transients on the bus. If the input exceeds that, the over-voltage protection shuts down the charger. Charge current is constant and programmable via an external resistor. The 500 mA max is the ceiling; you set a lower current if the upstream USB port or thermal environment demands it. Battery regulation voltage is 4.2V — the standard termination for a single Li-ion cell. The timer-based programmable feature ends the charge cycle after a set period, preventing overcharge if the cell never reaches the termination voltage.
It is a current-design part, safe to specify for new builds.