ZHCSGY5A October   2017  – December 2017


  1. 特性
  2. 应用范围
  3. 说明
    1.     典型应用电路
  4. 修订历史记录
  5. 说明 (续)
  6. Device Comparison Table
  7. Pin Configuration and Functions
    1.     Pin Functions
    2. 7.1 EN1/EN2 Settings
  8. Specifications
    1. 8.1 Absolute Maximum Ratings
    2. 8.2 ESD Ratings
    3. 8.3 Recommended Operating Conditions
    4. 8.4 Thermal Information
    5. 8.5 Dissipation Ratings
    6. 8.6 Electrical Characteristics
    7. 8.7 Typical Characteristics
  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. Input Source Connected (ADAPTER or USB)
          1. Input DPM Mode (VIN-DPM)
          2. DPPM Mode
          3. Battery Supplement Mode
        2. Input Source Not Connected
      5. 9.3.5 Battery Charging
        1. Charge Current Translator
        2. Battery Detection and Recharge
        3. Battery Disconnect (SYSOFF Input, bq24076, bq24078)
        4. Dynamic Charge Timers (TMR Input)
        5. Status Indicators (PGOOD, CHG)
        6. 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. bq2407x Charger Design Example
          1. System ON/OFF (SYSOFF) (bq24076 or bq24078 only)
        2. Calculations
          1. Program the Fast Charge Current (ISET):
          2. Program the Input Current Limit (ILIM)
          3. Program 6.25-hour Fast-Charge Safety Timer (TMR)
        3. TS Function
        4. CHG and PGOOD
        5. Selecting IN, OUT, and BAT Pin Capacitors
      3. 10.2.3 Application Curves
  11. 11Power Supply Recommendations
  12. 12Layout
    1. 12.1 Layout Guidelines
    2. 12.2 Layout Example
    3. 12.3 Thermal Considerations
  13. 13器件和文档支持
    1. 13.1 器件支持
      1. 13.1.1 Third-Party Products Disclaimer
    2. 13.2 相关链接
    3. 13.3 接收文档更新通知
    4. 13.4 社区资源
    5. 13.5 商标
    6. 13.6 静电放电警告
    7. 13.7 Glossary
  14. 14机械、封装和可订购信息


机械数据 (封装 | 引脚)
散热焊盘机械数据 (封装 | 引脚)

Dynamic Charge Timers (TMR Input)

The bq2407x devices contain internal safety timers for the pre-charge and fast-charge phases to prevent potential damage to the battery and the system. The timers begin at the start of the respective charge cycles. The timer values are programmed by connecting a resistor from TMR to VSS. The resistor value is calculated using the following equation:

Equation 4. tPRECHG = KTMR × RTMR
Equation 5. tMAXCHG = 10 × KTMR × RTMR

Leave TMR unconnected to select the internal default timers. Disable the timers by connecting TMR to VSS.

Reset the timers by toggling the CE pin, or by toggling EN1, EN2 pin to put the device in and out of USB suspend mode (EN1 = HI, EN2 = HI).

Note that timers are suspended when the device is in thermal shutdown, and the timers are slowed proportionally to the charge current when the device enters thermal regulation.

During the fast charge phase, several events increase the timer durations.

  • The system load current activates the DPPM loop which reduces the available charging current
  • The input current is reduced because the input voltage has fallen to VIN(LOW)
  • The device has entered thermal regulation because the IC junction temperature has exceeded TJ(REG)

During each of these events, the internal timers are slowed down proportionately to the reduction in charging current. For example, if the charging current is reduced by half for two minutes, the timer clock is reduced to half the frequency and the counter counts half as fast resulting in only one minute of "counting" time.

If the pre charge timer expires before the battery voltage reaches VLOWV, the bq2407x indicates a fault condition. Additionally, if the battery current does not fall to ITERM before the fast charge timer expires, a fault is indicated. The CHG output flashes at approximately 2 Hz to indicate a fault condition. The fault condition is cleared by toggling CE or the input power, entering/ exiting USB suspend mode, or an OVP event.