1 Features
1• Single-Cell Li-Ion Battery Fuel Gauge
– Resides on System Board
– Supports Embedded or Removable Batteries
– Powered Directly from Battery with Integrated
LDO
– Low-Value Integrated Sense Resistor
(7 mΩ, Typical)
• Easy-to-Configure Fuel Gauging Based on
Patented Impedance Track™ Technology
– Reports Remaining Capacity and State-of-
Charge (SOC) with Smoothing Filter
– Automatically Adjusts for Battery Aging, Self-
Discharge, Temperature, and Rate Changes
– Battery State-of-Health (Aging) Estimation
• Microcontroller Peripheral Supports:
– 400-kHz I2C Serial Interface
– Configurable SOC Interrupt or
Battery Low Digital Output Warning
– Internal Temperature Sensor or
Host-Reported Temperature

2 Applications
• Smartphones, Feature Phones, and Tablets
• Digital Still and Video Cameras
• Handheld Terminals
• MP3 or Multimedia Players

3 Description
The Texas Instruments bq27421-G1 fuel gauge is a
minimally configured microcontroller peripheral that provides system-side fuel gauging for single-cell Li-
Ion batteries. The device requires very little user
configuration and system microcontroller firmware
development.
The bq27421-G1 fuel gauge uses the patented
Impedance TrackTM algorithm for fuel gauging, and
provides information such as remaining battery
capacity (mAh), state-of-charge (%), and battery voltage (mV).
Battery fuel gauging with the bq27421-G1 fuel gauge requires connections only to PACK+ (P+) and PACK–
(P–) for a removable battery pack or embedded
battery circuit. The tiny 9-ball, 1.62 mm × 1.58 mm,
0.5-mm pitch NanoFree™ chip scale package
(DSBGA) is ideal for space-constrained applications.