Single-cell Li-Ion charger with I²C control
The Texas Instruments LP3921SQE/NOPB is a single-cell Lithium Ion battery charger IC from the Boomer® series, designed for constant-current, constant-voltage charging with a programmable charge current up to 950 mA. It communicates over an I²C interface, making it a good fit for portable devices where the host microcontroller manages the charging profile. The 32-WFQFN Exposed Pad package (5x5 mm) keeps the footprint small, and the -40°C to 85°C operating range means it can live in outdoor or industrial gear, not just a phone.
Package and mounting
The 950 mA max charge current is programmable via the I²C bus, so you can dial it down for smaller cells or slow charging. That constant-current phase is the bulk of the charge cycle for a single Li-Ion cell at 4.2 V. The fault protection covers over-temperature and reverse current — handy if the battery is connected backwards or the charger sees a thermal event. The 5.5 V max supply voltage is typical for USB-powered or 5 V rail designs.
Package and mounting — field-swap reality
It is a 32-lead WFQFN with an exposed pad, surface-mount only. No lab, no bench — if you are swapping this on site, you need a hot-air station and a steady hand. The exposed pad is the main thermal path; the datasheet layout shows the recommended via pattern under the pad. The Tape & Reel or Cut Tape option covers both production and prototype volumes.
Lifecycle — no LTB risk
The LP3921SQE/NOPB is listed as Active in production and ROHS3 compliant. For a BOM line that needs a single-cell charger, this part is safe to qualify for new designs.