Single-cell fuel gauge with impedance tracking
The Texas Instruments BQ27505YZGT-J1 is a single-cell Li-Ion battery monitor from the Impedance Track™ series, designed to report state-of-charge with an algorithm that learns the battery's impedance over charge/discharge cycles. It communicates over an I²C interface to the host, making it a drop-in for portable systems that already use that bus for battery management.
NRND — plan a transition for new BOMs
This part carries a Not Recommended for New Designs (NRND) status. It is still available for existing production runs, but TI advises against qualifying it into a new BOM. For a new design, look across the BQ2750x family for a current-generation replacement with the same Impedance Track™ core and I²C interface. The board footprint must match TI's recommended land pattern; the small body (roughly 2.0 × 1.5 mm) leaves little margin for misalignment.
Temperature grade and operating envelope
This is not a part for under-hood automotive or extended 105°C industrial applications — the gauge IC itself may survive, but the battery model accuracy degrades outside the characterised range.