Tracks the state of charge of a single-cell Li-ion battery and reports it over I2C as a percentage, remaining capacity, voltage, and more. It uses TI's Impedance Track algorithm to stay accurate as the battery ages and across temperature, without the runtime learning cycles older gauges needed, and it integrates the sense element so an external sense resistor sets the current range. A GPOUT pin flags low-battery or state-of-charge events. The standard small fuel gauge for handhelds and wearables.

Pinout

Pin	Name	Type	Function
1	SDA	bidirectional	Slave I2C serial data. Open-drain; requires an external ~10-kΩ pull-up to VDD (typical). If external pull-ups can be disconnected during normal operation, add a 1-MΩ pull-down to VSS to avoid floating inputs.
2	SCL	bidirectional	Slave I2C serial clock from system master. Open-drain; requires an external ~10-kΩ pull-up to VDD. Add a 1-MΩ pull-down to VSS if external pull-ups can be disconnected.
3	VSS	power_in	Device ground (0 V) reference pin.
4	NC	unconnected	No internal connection. May be left floating or tied to VSS.
5	VDD	power_out	1.8-V internal LDO regulator output. Decouple with a 0.47-µF ceramic capacitor to VSS. Not intended to power other devices in the system.
6	BAT	power_in	LDO regulator input and battery voltage measurement input (analog). Kelvin sense connect to the positive battery terminal (PACKP). Decouple with a 1-µF capacitor to VSS placed close to the gauge.
7	SRN	input	Coulomb-counter differential input (negative). High-side connection expecting an external 10-mΩ, 1% sense resistor. Kelvin sense connect to the opposite side of the sense resistor from SRP (positive connection to system VSYS).
8	SRP	input	Coulomb-counter differential input (positive). Kelvin sense connect SRP to the positive battery-terminal (PACKP) side of the external 10-mΩ sense resistor.
9	NC	unconnected	No internal connection. May be left floating or tied to VSS.
10	BIN	input	Battery insertion detection digital input. With OpConfig [BI_PU_EN]=1 (default) a logic low indicates battery insertion. For removable packs, connect BIN to VSS through a pack thermistor (typ. 10-kΩ) with an internal-side 1.8-MΩ pull-up to VDD; for embedded batteries use a 10-kΩ pull-down to VSS. Must connect only to VDD and not an external rail; never short directly to VCC or VSS.
11	NC	unconnected	No internal connection. May be left floating or tied to VSS.
12	GPOUT	output	Open-drain multipurpose output. Configurable via OpConfig [BATLOWEN]: when set, indicates BAT_LOW; when cleared (default), acts as SOC interrupt (SOC_INT) pulsed on events such as SOC changes. Requires an external 10-kΩ pull-up; do not leave floating. Recommended to route to a host-MCU GPIO so the host can wake the gauge from shutdown.

Key specifications

Parameter	Value
Type	Single-cell Li-ion fuel gauge
Algorithm	Impedance Track
Reports	State of charge, remaining capacity, voltage, temperature
Interface	I2C
Alert	GPOUT (SOC / low-battery)
Supply	2.45-4.5 V (from battery)
Package	SON-12

Ordering variants

BQ27441DRZR-G1A (SON-12)
BQ27441DRZR-G1B (different chem profile)

CAD (KiCad official)

Symbol: Battery_Management:BQ27441-G1 (KiCad official)
Footprint: Package_SON:Texas_S-PDSO-N12
3D model: SON-12 (KiCad packages3D, STEP)

Provenance

Data extracted from the manufacturer datasheet, not a distributor listing:

Datasheet: Texas Instruments datasheet (28 pp, sha256 8779b67adfe7683f, retrieved 2026-08-17, tier: manufacturer)
Extractor: ds2sf (Claude). Every pin and dimension is cited to a datasheet page; it refuses to fabricate.
CAD: KiCad official libraries (CC-BY-SA 4.0).

Datasheet PDF