Single-cell Li-Ion charging with USB input
The Texas Instruments BQ24072TRGTT is a linear battery charger for single-cell Lithium-Ion packs, accepting power from a USB port and delivering a programmable constant charge current up to 1.5 A. The termination voltage is fixed at 4.2 V, matching the standard 1S Li-Ion cell profile.
Charge current and thermal budget in a 3×3 mm package
The maximum charge current of 1.5 A is set with an external resistor; the charge current is constant and programmable, with a separate timer resistor setting the safety timeout. The 16-VFQFN package with exposed pad (3×3 mm body) dissipates the pass-element heat — at 1.5 A the input-to-battery voltage drop times current lands in the pad's thermal budget, so board layout with adequate copper area on the pad is necessary to keep junction temperature below the 125 °C TJ max. Supply voltage range goes up to 6.4 V, which covers the 5 V USB bus with margin for cable drops and hot-plug transients.
Protection set covers the common failure modes
On-chip fault protection includes over-temperature, over-voltage, reverse-current blocking, and short-circuit — the charger shuts down or limits current without an external supervisor or series diode.