SLUSB85E May 2013  – January 2016


  1. Features
  2. Applications
  3. Description
  4. Revision History
  5. Device Comparison Table
  6. Pin Configuration and Functions
  7. Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Supply Current
    6. 7.6 Digital Input and Output DC Characteristics
    7. 7.7 LDO Regulator, Wake-Up, and Auto-Shutdown DC Characteristics
    8. 7.8 ADC (Temperature and Cell Measurement) Characteristics
    9. 7.9 Integrating ADC (Coulomb Counter) Characteristics
    10. 7.10Integrated Sense Resistor Characteristics, -40°C to 85°C
    11. 7.11Integrated Sense Resistor Characteristics, -40°C to 70°C
    12. 7.12I2C-Compatible Interface Communication Timing Characteristics
    13. 7.13Typical Characteristics
  8. Detailed Description
    1. 8.1Overview
    2. 8.2Functional Block Diagram
    3. 8.3Feature Description
    4. 8.4Device Functional Modes
    5. 8.5Programming
      1. 8.5.1Standard Data Commands
      2. 8.5.2Control(): 0x00 and 0x01
      3. 8.5.3Extended Data Commands
      4. 8.5.4Communications
        1. Interface
        2. Time Out
        3. Command Waiting Time
        4. Clock Stretching
  9. Applications and Implementation
    1. 9.1Application Information
    2. 9.2Typical Applications
      1. 9.2.1Design Requirements
      2. 9.2.2Detailed Design Procedure
        1. Voltage Sense Input
        2. LDO Capacitor
        3. Resistor Selection
      3. 9.2.3Application Curves
  10. 10Power Supply Recommendation
    1. 10.1Power Supply Decoupling
  11. 11Layout
    1. 11.1Layout Guidelines
    2. 11.2Layout Example
  12. 12Device and Documentation Support
    1. 12.1Documentation Support
      1. 12.1.1Related Documentation
    2. 12.2Community Resources
    3. 12.3Trademarks
    4. 12.4Electrostatic Discharge Caution
    5. 12.5Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

Refer to the PDF data sheet for device specific package drawings

Mechanical Data (Package|Pins)
  • YZF|9
Orderable Information

1 Features

  • 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.

Device Information(1)

bq27421-G1YZF (9)1.62 mm × 1.58 mm
  1. For all available packages, see the orderable addendum at the end of the data sheet.

Simplified Schematic

bq27421-G1 typ_app_bq27421.gif

4 Revision History

Changes from D Revision (July 2015) to E Revision

Changes from C Revision (December 2014) to D Revision

Changes from B Revision (November 2014) to C Revision

  • Changed simplified schematic by adding 1-µF capacitorGo
  • Added description for connecting a 1-µF capacitorGo
  • Added information for connecting GPOUTGo
  • Changed connection description for BAT pinGo
  • Changed "recommend" to "required"Go