ZHCSLN5D december   2010  – september 2020 BQ24133

PRODUCTION DATA  

  1.   1
  2. 1 特性
  3. 2 应用
  4. 3 说明
  5. 4 Revision History
  6. 5 Description (continued)
  7. 6 Device Comparison Table
  8. 7 Pin Configuration and Functions
    1.     Pin Functions
  9. 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 Electrical Characteristics
    6. 8.6 Typical Characteristics
  10. 9 Detailed Description
    1. 9.1 Overview
    2. 9.2 Functional Block Diagram
    3. 9.3 Feature Description
      1. 9.3.1  Battery Voltage Regulation
      2. 9.3.2  Battery Current Regulation
      3. 9.3.3  Battery Precharge Current Regulation
      4. 9.3.4  Input Current Regulation
      5. 9.3.5  Charge Termination, Recharge, And Safety Timers
      6. 9.3.6  Power Up
      7. 9.3.7  Input Undervoltage Lockout (UVLO)
      8. 9.3.8  Input Overvoltage/Undervoltage Protection
      9. 9.3.9  Enable and Disable Charging
      10. 9.3.10 System Power Selector
      11. 9.3.11 Converter Operation
      12. 9.3.12 Automatic Internal Soft-Start Charger Current
      13. 9.3.13 Charge Overcurrent Protection
      14. 9.3.14 Charge Undercurrent Protection
      15. 9.3.15 Battery Detection
        1. 9.3.15.1 Example
      16. 9.3.16 Battery Short Protection
      17. 9.3.17 Battery Overvoltage Protection
      18. 9.3.18 Temperature Qualification
      19. 9.3.19 MOSFET Short Circuit and Inductor Short Circuit Protection
      20. 9.3.20 Thermal Regulation and Shutdown Protection
      21. 9.3.21 Timer Fault Recovery
      22. 9.3.22 Charge Status Outputs
    4. 9.4 Device Functional Modes
  11. 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 Inductor Selection
        2. 10.2.2.2 Input Capacitor
        3. 10.2.2.3 Output Capacitor
        4. 10.2.2.4 Input Filter Design
        5. 10.2.2.5 Input ACFET and RBFET Selection
        6. 10.2.2.6 Inductor, Capacitor, and Sense Resistor Selection Guidelines
      3. 10.2.3 Application Curve
    3. 10.3 System Examples
  12. 11Power Supply Recommendations
  13. 12Layout
    1. 12.1 Layout Guidelines
    2. 12.2 Layout Examples
  14. 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 静电放电警告
    6. 13.6 术语表
  15. 14Mechanical, Packaging, and Orderable Information

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订购信息

9.3.10 System Power Selector

The IC automatically switches adapter or battery power to the system load. The battery is connected to the system by default during power up or during SLEEP mode. When the adapter plugs in and the voltage is above the battery voltage, the IC exits SLEEP mode. The battery is disconnected from the system and the adapter is connected to the system after exiting SLEEP. An automatic break-before-make logic prevents shoot-through currents when the selectors switch.

The ACDRV is used to drive a pair of back-to-back N-channel power MOSFETs between adapter and ACP with sources connected together to CMSRC. The N-channel FET with the drain connected to the ACP (Q2, RBFET) provides reverse battery discharge protection, and minimizes system power dissipation with its low-RDSON. The other N-channel FET with drain connected to adapter input (Q1, ACFET) separates battery from adapter, and provides a limited dI/dt when connecting the adapter to the system by controlling the FET turnon time. The /BATDRV controls a P-channel power MOSFET (Q3, BATFET) placed between battery and system with drain connected to battery.

Before the adapter is detected, the ACDRV is pulled to CMSRC to keep ACFET off, disconnecting the adapter from system. /BATDRV stays at ACN - 6 V (clamp to ground) to connect battery to system if all the following conditions are valid:

  • VAVCC > VUVLO (battery supplies AVCC)
  • VACN < VSRN + 200 mV

After the device comes out of SLEEP mode, the system begins to switch from battery to adapter. The AVCC voltage has to be 300 mV above SRN to enable the transition. The break-before-make logic keeps both ACFET and BATFET off for 10 µs before ACFET turns on. This prevents shoot-through current or any large discharging current from going into the battery. The /BATDRV is pulled up to ACN and the ACDRV pin is set to CMSRC +
6 V by an internal charge pump to turn on N-channel ACFET, connecting the adapter to the system if all the following conditions are valid:

  • VACUV < VOVPSET < VACOV
  • VAVCC > VSRN + 300 mV

When the adapter is removed, the IC turns off ACFET and enters SLEEP mode.

BATFET keeps off until the system drops close to SRN. The BATDRV pin is driven to ACN - 6V by an internal regulator to turn on P-channel BATFET, connecting the battery to the system.

Asymmetrical gate drive provides fast turnoff and slow turnon of the ACFET and BATFET to help the break-before-make logic and to allow a soft-start at turnon of both MOSFETs. The delay time can be further increased, by putting a capacitor from gate to source of the power MOSFETs.