Single-cell fuel gauge with Impedance Track™
The BQ27505YZGT-J3 is a battery monitor IC from Texas Instruments' Impedance Track™ series, designed to report state-of-charge for single-cell Lithium-Ion packs over an I²C bus. This is the part you reach for when you need a fuel gauge that compensates for battery aging and temperature — the Impedance Track algorithm learns the battery's impedance over time rather than relying on a fixed lookup table. The I²C interface keeps the BOM simple — just two pull-up resistors to the host MCU's bus.
Package and hand-solderability
Housed in a 12-bump DSBGA (0.5 mm pitch, no leads), this is a fine-pitch BGA that requires a stencil and reflow oven — not a hand-solder-friendly part. The 12-DSBGA supplier device package is the same as the 12-UFBGA case code; the bumps are under the die, so inspection needs an X-ray or a microscope on the side fillets. For a weekend prototype, you'd want a breakout board or a pre-assembled module. In production, the package saves board area — the 12-bump array fits in roughly 2 mm × 2 mm, leaving room for the rest of the power management section.
It is ROHS3 compliant, so it ships into EU and California markets without exemption paperwork. The base product number BQ27505 covers multiple package and tape options; the -J3 suffix denotes the specific DSBGA variant in tape-and-reel or cut-tape format. No official second-source cross-reference exists — the BQ296217DSGT is a battery protection IC (over-voltage monitor for 2-4 cells), not a fuel gauge, and does not drop into the same socket.