ZHCSIF0N September   2008  – October 2021 BQ24072 , BQ24073 , BQ24074 , BQ24075 , BQ24079

PRODUCTION DATA  

  1. 1 特性
  2. 2 应用
  3. 3 说明
  4. 4 Revision History
  5. 5 说明（续）
  6. 6 Device Comparison Table
  7. 7 Pin Configuration and Functions
  8. 8 Specifications
    1. 8.1 Absolute Maximum Ratings (1)
    2. 8.2 ESD Ratings
    3. 8.3 Recommended Operating Conditions
    4. 8.4 Thermal Information
    5. 8.5 Electrical Characteristics
    6. 8.6 Typical Characteristics
  9. 9 Detailed Description
    1. 9.1 Overview
    2. 9.2 Functional Block Diagram
    3. 9.3 Feature Description
      1. 9.3.1 Undervoltage Lockout (UVLO)
      2. 9.3.2 Power On
      3. 9.3.3 Overvoltage Protection (OVP)
      4. 9.3.4 Dynamic Power Path Management
        1. 9.3.4.1 Input Source Connected (ADAPTER or USB)
          1. 9.3.4.1.1 Input DPM Mode (VIN-DPM)
          2. 9.3.4.1.2 DPPM Mode
          3. 9.3.4.1.3 Battery Supplement Mode
        2. 9.3.4.2 Input Source Not Connected
      5. 9.3.5 Battery Charging
        1. 9.3.5.1 Charge Current Translator
        2. 9.3.5.2 Adjustable Termination Threshold (ITERM Input, BQ24074)
        3. 9.3.5.3 Termination Disable (TD Input, BQ24072, BQ24073)
        4. 9.3.5.4 Battery Detection and Recharge
        5. 9.3.5.5 Battery Disconnect (SYSOFF Input, BQ24075, BQ24079)
        6. 9.3.5.6 Dynamic Charge Timers (TMR Input)
        7. 9.3.5.7 Status Indicators ( PGOOD, CHG)
        8. 9.3.5.8 Thermal Regulation and Thermal Shutdown
      6. 9.3.6 Battery Pack Temperature Monitoring
    4. 9.4 Device Functional Modes
      1. 9.4.1 Sleep Mode
      2. 9.4.2 Explanation of Deglitch Times and Comparator Hysteresis
  10. 10Application and Implementation
    1. 10.1 Application Information
    2. 10.2 Typical Application
      1. 10.2.1 Design Requirements
      2. 10.2.2 Detailed Design Procedure
        1. 10.2.2.1 BQ2407x Charger Design Example
          1. 10.2.2.1.1 Termination Disable (TD) (BQ24072, BQ24073 only)
          2. 10.2.2.1.2 System ON/OFF (SYSOFF) (BQ24075 or BQ24079 only)
        2. 10.2.2.2 Calculations
          1. 10.2.2.2.1 Program the Fast Charge Current (ISET):
          2. 10.2.2.2.2 Program the Input Current Limit (ILIM)
          3. 10.2.2.2.3 Program the Termination Current Threshold (ITERM) (BQ24074 only)
          4. 10.2.2.2.4 Program 6.25-hour Fast-Charge Safety Timer (TMR)
        3. 10.2.2.3 TS Function
        4. 10.2.2.4 CHG and PGOOD
        5. 10.2.2.5 Selecting IN, OUT, and BAT Pin Capacitors
      3. 10.2.3 Application Curves
    3. 10.3 System Examples
      1. 10.3.1 Standalone Charger
      2. 10.3.2 Disconnecting the Battery From the System
  11. 11Power Supply Recommendations
  12. 12Layout
    1. 12.1 Layout Guidelines
    2. 12.2 Layout Example
    3. 12.3 Thermal Considerations
  13. 13Device and Documentation Support
    1. 13.1 Device Support
      1. 13.1.1 第三方产品免责声明
    2. 13.2 接收文档更新通知
    3. 13.3 支持资源
    4. 13.4 Trademarks
    5. 13.5 Electrostatic Discharge Caution
    6. 13.6 术语表
  14. 14Mechanical, Packaging, and Orderable Information

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9.3.5.5 Battery Disconnect (SYSOFF Input, BQ24075, BQ24079)

The BQ24075 and BQ24079 feature a SYSOFF input that allows the user to turn the FET Q2 off and disconnect the battery from the OUT pin. This is useful for disconnecting the system load from the battery, factory programming where the battery is not installed or for host side impedance track fuel gauging, such as bq27500, where the battery open circuit voltage level must be detected before the battery charges or discharges. The /CHG output remains low when SYSOFF is high. Connect SYSOFF to VSS, to turn Q2 on for normal operation. SYSOFF is internally pulled to VBAT through ~5 MΩ resistor.