ZHCSMS4B November   2020  – September 2021 TPS25864-Q1 , TPS25865-Q1

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
    2. 8.2 ESD Ratings
    3. 8.3 Recommended Operating Conditions
    4. 8.4 Thermal Information
    5. 8.5 Electrical Characteristics
    6. 8.6 Timing Requirements
    7. 8.7 Switching Characteristics
    8. 8.8 Typical Characteristics
  9. 9 Parameter Measurement Information
  10. 10Detailed Description
    1. 10.1 Overview
    2. 10.2 Functional Block Diagram
    3. 10.3 Feature Description
      1. 10.3.1  Power-Down or Undervoltage Lockout
      2. 10.3.2  Input Overvoltage Protection (OVP) - Continuously Monitored
      3. 10.3.3  Buck Converter
      4. 10.3.4  FREQ/SYNC
      5. 10.3.5  Bootstrap Voltage (BOOT)
      6. 10.3.6  Minimum ON-Time, Minimum OFF-Time
      7. 10.3.7  Internal Compensation
      8. 10.3.8  Selectable Output Voltage (VSET)
      9. 10.3.9  Current Limit and Short Circuit Protection
        1. 10.3.9.1 USB Switch Current Limit
        2. 10.3.9.2 Interlocking for Two-Level USB Switch Current Limit
        3. 10.3.9.3 Cycle-by-Cycle Buck Current Limit
        4. 10.3.9.4 OUT Current Limit
      10. 10.3.10 Cable Compensation
      11. 10.3.11 Thermal Management With Temperature Sensing (TS) and OTSD
      12. 10.3.12 Thermal Shutdown
      13. 10.3.13 USB Specification Overview
      14. 10.3.14 USB Port Operating Modes
        1. 10.3.14.1 Dedicated Charging Port (DCP) Mode
          1. 10.3.14.1.1 DCP BC1.2 and YD/T 1591-2009
          2. 10.3.14.1.2 DCP Divider-Charging Scheme
          3. 10.3.14.1.3 DCP 1.2-V Charging Scheme
        2. 10.3.14.2 DCP Auto Mode
    4. 10.4 Device Functional Modes
      1. 10.4.1 Shutdown Mode
      2. 10.4.2 Active Mode
  11. 11Application and Implementation
    1. 11.1 Application Information
    2. 11.2 Typical Applications
      1. 11.2.1 Design Requirements
      2. 11.2.2 Detailed Design Procedure
        1. 11.2.2.1 Output Voltage Setting
        2. 11.2.2.2 Switching Frequency
        3. 11.2.2.3 Inductor Selection
        4. 11.2.2.4 Output Capacitor Selection
        5. 11.2.2.5 Input Capacitor Selection
        6. 11.2.2.6 Bootstrap Capacitor Selection
        7. 11.2.2.7 Undervoltage Lockout Set-Point
        8. 11.2.2.8 Cable Compensation Set-Point
      3. 11.2.3 Application Curves
  12. 12Power Supply Recommendations
  13. 13Layout
    1. 13.1 Layout Guidelines
    2. 13.2 Layout Example
    3. 13.3 Ground Plane and Thermal Considerations
  14. 14Device and Documentation Support
    1. 14.1 接收文档更新通知
    2. 14.2 支持资源
    3. 14.3 Trademarks
    4. 14.4 Electrostatic Discharge Caution
    5. 14.5 术语表
  15. 15Mechanical, Packaging, and Orderable Information

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11.2.2.7 Undervoltage Lockout Set-Point

The system undervoltage Lockout (UVLO) is adjusted using the external voltage divider network of RENT and RENB.  The UVLO has two thresholds, one for power up when the input voltage is rising and one for power down or brownouts when the input voltage is falling. Equation 12 can be used to determine the VIN UVLO level.

Equation 12. GUID-A3883276-E215-43BD-B0D2-F1E58A34631A-low.gif

The EN rising threshold (VENH) for the TPS2586x-Q1 is set to be 1.3 V (typical). Choose 10 kΩ for RENB to minimize input current from the supply. If the desired VIN UVLO level is at 6 V, then the value of RENT can be calculated using Equation 13:

Equation 13. GUID-83BFA7E9-D453-4860-A435-996D19F64A4C-low.gif

Equation 13 yields a value of 36.1 kΩ. The resulting falling UVLO threshold equals 5.5 V and can be calculated by Equation 14, where EN hysteresis (VEN_HYS) is 0.1 V (typical).

Equation 14. GUID-F7A09B71-9571-44AA-9FC4-11D59CA84518-low.gif

Note that it cannot connect EN to IN pin directly for self-startup. Because the voltage rating of EN pin is 11 V, tying it to VIN directly damages the device. The simplest way to enable the operation of the TPS2586x-Q1 is to connect the EN to VSENSE. This connection allows the automatic startup when VIN is within the operation range.