2.5 A single-cell Li-ion charger with I²C and USB control
The Renesas R2J20052NS#W0 is a single-cell lithium-ion battery charger IC that delivers up to 2.5 A programmable charge current to a 4.2 V termination voltage. The I²C and USB interface lets a host microcontroller set the charge current, monitor charging status, and negotiate USB bus current limits — making this part suitable for portable devices, power banks, and handheld instruments where the charging profile must adapt to the input source. The 5.8 V maximum supply voltage means the IC accepts standard 5 V USB bus power directly, with headroom for cable drop. Over-temperature fault protection shuts down the charger if the die temperature exceeds the safe operating limit, protecting both the IC and the battery during high-current charging in confined enclosures.
Package and thermal management for board integration
Housed in an 18-PowerUFDFN package (3.4 x 4.5 mm, 18-DFN), the IC exposes a large thermal pad on the bottom side. The supplier device package 18-DFN (3.4x4.5) requires a matching copper land and via array under the pad to conduct heat into the PCB ground plane — critical for sustaining the full 2.5 A charge current without thermal foldback.