I2C-controlled multi-cell charger for portable and industrial gear
The Texas Instruments BQ25792RQMR is a switch-mode battery charger IC that handles 1 to 4 series Li-Ion or Li-Polymer cells with a programmable charge current up to 5 A. It accepts an input voltage up to 24 V, which covers USB PD adapters and higher-voltage wall warts without an extra pre-regulator. The I²C interface lets the system microcontroller set the charge current, voltage, and timer thresholds on the fly — useful for multi-chemistry packs or adaptive fast-charge profiles.
5 A charge current and cell-count flexibility
The 5 A maximum charge current is the headline number, but the real-world limit depends on the thermal design of the 29-VQFN-HR (4x4 mm) package and the board’s copper pour. For a 2-cell pack at 5 A, the power dissipation in the internal FETs will push the junction temperature — plan for adequate thermal vias under the exposed pad. The 1-to-4 cell range means the same BOM can serve a single-cell power bank and a 4-cell power tool charger with only firmware changes. Fault protection covers over-current, over-voltage, and short-circuit conditions on the battery and input rails. The constant-current / constant-voltage profile is standard Li-Ion charging, but the programmable timer prevents a stuck cell from cooking if the termination current is never reached.