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. 7.10 Integrated Sense Resistor Characteristics, -40°C to 85°C
    11. 7.11 Integrated Sense Resistor Characteristics, -40°C to 70°C
    12. 7.12 I2C-Compatible Interface Communication Timing Characteristics
    13. 7.13 Typical Characteristics
  8. Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
    4. 8.4 Device Functional Modes
    5. 8.5 Programming
      1. 8.5.1 Standard Data Commands
      2. 8.5.2 Control(): 0x00 and 0x01
      3. 8.5.3 Extended Data Commands
      4. 8.5.4 Communications
        1. I2C Interface
        2. I2C Time Out
        3. I2C Command Waiting Time
        4. I2C Clock Stretching
  9. Applications and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Applications
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. BAT Voltage Sense Input
        2. Integrated LDO Capacitor
        3. Sense Resistor Selection
      3. 9.2.3 Application Curves
  10. 10Power Supply Recommendation
    1. 10.1 Power Supply Decoupling
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Documentation Support
      1. 12.1.1 Related Documentation
    2. 12.2 Community Resources
    3. 12.3 Trademarks
    4. 12.4 Electrostatic Discharge Caution
    5. 12.5 Glossary
  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
Thermal pad, mechanical data (Package|Pins)
Orderable Information

12 Device and Documentation Support

12.1 Documentation Support

12.1.1 Related Documentation

  • bq27421-G1 Technical Reference Manual (SLUUAC5)
  • bq27421 EVM: Single-Cell Technology User's Guide (SLUUA63)
  • Quickstart Guide for bq27421-G1 (SLUUAH7)
  • Single Cell Gas Gauge Circuit Design (SLUA456)
  • Key Design Considerations for the bq27500 and bq27501 (SLUA439)
  • Single Cell Impedance Track Printed-Circuit Board Layout Guide (SLUA457)
  • ESD and RF Mitigation in Handheld Battery Electronics (SLUA460)

12.2 Community Resources

The following links connect to TI community resources. Linked contents are provided "AS IS" by the respective contributors. They do not constitute TI specifications and do not necessarily reflect TI's views; see TI's Terms of Use.

    TI E2E™ Online Community TI's Engineer-to-Engineer (E2E) Community. Created to foster collaboration among engineers. At, you can ask questions, share knowledge, explore ideas and help solve problems with fellow engineers.
    Design Support TI's Design Support Quickly find helpful E2E forums along with design support tools and contact information for technical support.

12.3 Trademarks

Impedance Track, NanoFree, E2E are trademarks of Texas Instruments.

All other trademarks are the property of their respective owners.

12.4 Electrostatic Discharge Caution


This integrated circuit can be damaged by ESD. Texas Instruments recommends that all integrated circuits be handled with appropriate precautions. Failure to observe proper handling and installation procedures can cause damage.

ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may be more susceptible to damage because very small parametric changes could cause the device not to meet its published specifications.

12.5 Glossary

SLYZ022TI Glossary.

This glossary lists and explains terms, acronyms, and definitions.