Single-cell Li-Ion fuel gauge with Impedance Track™
The Texas Instruments BQ27520YZFT-G4 is a single-cell Lithium Ion battery monitor from the Impedance Track™ series. It uses TI's learning-based algorithm to report state-of-charge, state-of-health, and remaining capacity over an I²C interface — no external current-sense resistor needed because the gauge integrates the coulomb counter on-chip.
I²C interface and single-cell topology
Communication with the host processor runs over a standard I²C bus. The gauge reports voltage, current, temperature, and accumulated charge — the host reads these registers to compute remaining run time. No proprietary protocol or extra GPIOs are required. The part is designed for exactly one series cell (1S). For multi-cell packs (2S or higher), an external cell-balancing circuit and a different gauge variant are needed. The BQ27520 does not include internal balancing FETs.
The base product number is BQ27520; the YZFT-G4 suffix denotes the 15-DSBGA package and the tape-and-reel / cut-tape shipping options. No official second-source or pin-compatible alternate is listed in the TI portfolio — the BQ27520 family is the only Impedance Track gauge in this footprint.