Single-cell Li-Ion fuel gauge in a 12-DSBGA package
The Texas Instruments BQ27505YZGR-J4 is a single-cell Lithium Ion battery monitor from the Impedance Track™ series. It reports remaining capacity and state-of-charge over an I²C interface, and is designed for portable devices where accurate fuel gauging extends run time. The 12-DSBGA package (0.5 mm pitch, 2.0 mm × 2.5 mm body) saves board area but demands careful solder-paste stencil design and X-ray inspection for reliable reflow.
For a single-source fuel gauge on a production BOM, this means no forced redesign cycle in the near term.
What the I²C interface and Impedance Track™ mean for the BOM
The I²C interface lets a host MCU read voltage, current, temperature, and state-of-charge without an ADC pin. The Impedance Track™ algorithm learns battery impedance over discharge cycles, so the reported remaining capacity stays accurate as the cell ages — a clear advantage over voltage-only gauges that drift with temperature and load. Because this is a monitor (not a protector or charger), the BOM still needs a separate battery protection IC and a charger front-end. The gauge sits on the cell side of the protection FET, drawing its supply from the battery itself.