SLUSBN7D January   2014  – April 2017

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Device Comparison Table
  6. 6 Pin Configuration and Functions
  7. 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 I2C-Compatible Interface Communication Timing Characteristics
    11. 7.11 Typical Characteristics
  8. 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. 8.5.4.1 I2C Interface
        2. 8.5.4.2 I2C Time Out
        3. 8.5.4.3 I2C Command Waiting Time
        4. 8.5.4.4 I2C Clock Stretching
  9. 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. 9.2.2.1 High-Side or Low-Side Sense Resistor
        2. 9.2.2.2 BAT Voltage Sense Input
        3. 9.2.2.3 Sense Resistor Selection
        4. 9.2.2.4 Communication Interface Lines
      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. 12.1.2 Community Resources
    2. 12.2 Trademarks
    3. 12.3 Electrostatic Discharge Caution
    4. 12.4 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

9 Applications and Implementation

NOTE

Information in the following application section is not part of the TI component specification, and TI does not warrant its accuracy or completeness. TI’s customers are responsible for determining suitability of components for their purposes. Customers should validate and test their design implementation to confirm system functionality.

9.1 Application Information

The bq27411-G1 device is a fuel gauging solution for single-cell Li-Ion battery packs. The device requires minimal configuration and uses One Time Programmable (OTP) Non-Volatile Memory (NVM) to avoid an initialization download by the system processor. To allow for optimal performance in the end application, special considerations must be taken to ensure minimization of measurement error through proper printed circuit board (PCB) board layout. Such requirements are detailed in Design Requirements.

9.2 Typical Applications

bq27411-G1 bq27411_DS_Schematic.gif Figure 5. Typical Application with High-Side Current Sense Resistor
bq27411-G1 bq27411_DS_Schematic_Low.gif Figure 6. Typical Application with Low-Side Current Sense Resistor

9.2.1 Design Requirements

As shipped from the Texas Instruments factory, many bq27411-G1 parameters in OTP NVM are left in the unprogrammed state (zero) while some parameters directly associated with the CHEMID are preprogrammed. This partially programmed configuration facilitates customization for each end application. Upon device reset, the contents of OTP are copied to associated volatile RAM-based Data Memory blocks. For proper operation, all parameters in RAM-based Data Memory require initialization—either by updating Data Memory parameters in a lab/evaluation situation or by programming the OTP for customer production. Chapter 5 in the bq27411-G1 Technical Reference Manual (SLUUAS7) shows the default value and a typically expected value appropriate for most applications.

9.2.2 Detailed Design Procedure

9.2.2.1 High-Side or Low-Side Sense Resistor

The bq27411-G1 device can be used with a high-side current resistor, as shown in Figure 5 or a low-side current resistor, as shown in Figure 6.

9.2.2.2 BAT Voltage Sense Input

A ceramic capacitor at the input to the BAT pin is used to bypass AC voltage ripple to ground, greatly reducing its influence on battery voltage measurements. It proves most effective in applications with load profiles that exhibit high-frequency current pulses (that is, cell phones) but is recommended for use in all applications to reduce noise on this sensitive high-impedance measurement node.

9.2.2.3 Sense Resistor Selection

Any variation encountered in the resistance present between the SRP and SRN pins of the fuel gauge will affect the resulting differential voltage, and derived current, it senses. As such, it is recommended to select a sense resistor with minimal tolerance and temperature coefficient of resistance (TCR) characteristics. The standard recommendation based on best compromise between performance and price is a 1% tolerance, 50-ppm drift sense resistor with a 1-W power rating.

9.2.2.4 Communication Interface Lines

A protection network composed of resistors and capacitors is recommended on each of the serial communication inputs to protect the fuel gauge from dangerous ESD transients.

9.2.3 Application Curves

bq27411-G1 D003_SLUSBH1.gif Figure 7. Voltage Accuracy
bq27411-G1 D002_SLUSBH1.gif Figure 9. Current Accuracy
bq27411-G1 D001_SLUSBH1.gif Figure 8. Temperature Accuracy