Single-cell fuel gauge with Impedance Track
The BQ27542DRZR-G1 is a single-cell Li-Ion battery monitor from Texas Instruments' Impedance Track™ series. It reports state-of-charge through either an HDQ or I²C serial interface. The 12-VFDFN exposed-pad package keeps the footprint small — 2.5x4 mm in the 12-SON variant — which matters when the battery pack PCB has no room for a larger QFN. It does not cover the automotive under-hood band — that is the BQ79612PAPRQ1's territory with its -40°C to 125°C rating.
What the single-cell spec means for your BOM
The BQ27542DRZR-G1 is hard-limited to one series cell. If your pack is 2-cell or higher, this part will not work — you need a multi-cell gauge like the BQ2084DBT-V143, which handles 2 to 4 cells. The interface choice (HDQ vs I²C) is a firmware fork: HDQ is TI-proprietary and needs a dedicated GPIO bit-bang, while I²C is standard and shares the bus with other peripherals.
The base product number is BQ27542, so future die revisions or package variants will carry the same base number — watch for a suffix change if TI issues a PCN.