ZHCSK92E September   2019  – March 2022 TPS25840-Q1 , TPS25842-Q1

PRODUCTION DATA  

  1. 特性
  2. 应用
  3. 说明
  4. Revision History
  5. 说明(续)
  6. Device Comparison Table
  7. Pin Configuration and Functions
  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. 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  Buck Regulator
      2. 10.3.2  Enable/UVLO
      3. 10.3.3  Switching Frequency and Synchronization (RT/SYNC)
      4. 10.3.4  Spread-Spectrum Operation
      5. 10.3.5  VCC, VCC_UVLO
      6. 10.3.6  Minimum ON-time, Minimum OFF-time
      7. 10.3.7  Internal Compensation
      8. 10.3.8  Bootstrap Voltage (BOOT)
      9. 10.3.9  RSNS, RSET, RILIMIT and RIMON
      10. 10.3.10 Overcurrent and Short Circuit Protection
        1. 10.3.10.1 Current Limit Setting using RILIMIT
        2. 10.3.10.2 Buck Average Current Limit Design Example
        3. 10.3.10.3 External MOSFET Gate Drivers
        4. 10.3.10.4 Cycle-by-Cycle Buck Current Limit
      11. 10.3.11 Overvoltage, IEC and Short-to-Battery Protection
        1. 10.3.11.1 V BUS and V CSN/OUT Overvoltage Protection
        2. 10.3.11.2 DP_IN and DM_IN Protection
      12. 10.3.12 Cable Compensation
        1. 10.3.12.1 Cable Compensation Design Example
      13. 10.3.13 USB Port Control
      14. 10.3.14 FAULT Response
      15. 10.3.15 USB Specification Overview
      16. 10.3.16 Device Power Pins (IN, CSN/OUT, and PGND)
      17. 10.3.17 Thermal Shutdown
    4. 10.4 Device Functional Modes
      1. 10.4.1 Shutdown Mode
      2. 10.4.2 Active Mode
      3. 10.4.3 Device Truth Table (TT)
      4. 10.4.4 USB Port Operating Modes
        1. 10.4.4.1 Standard Downstream Port (SDP) Mode — USB 2.0, USB 3.0, and USB 3.1
        2. 10.4.4.2 Charging Downstream Port (CDP) Mode
        3. 10.4.4.3 Client Mode
      5. 10.4.5 High-bandwidth Data-line Switches
  11. 11Application and Implementation
    1. 11.1 Application Information
    2. 11.2 Typical Application
      1. 11.2.1 Design Requirements
      2. 11.2.2 Detailed Design Procedure
        1. 11.2.2.1  Output Voltage
        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  VCC Capacitor Selection
        8. 11.2.2.8  Enable and Under Voltage Lockout Set-Point
        9. 11.2.2.9  Current Limit Set-Point
        10. 11.2.2.10 Cable Compensation Set-Point
        11. 11.2.2.11 FAULT Resistor Selection
      3. 11.2.3 Application Curves
  12. 12Power Supply Recommendations
  13. 13Layout
    1. 13.1 Layout Guidelines
    2. 13.2 Ground Plane and Thermal Considerations
    3. 13.3 Layout Example
  14. 14Device and Documentation Support
    1. 14.1 Documentation Support
      1. 14.1.1 Related Documentation
    2. 14.2 Related Links
    3. 14.3 接收文档更新通知
    4. 14.4 支持资源
    5. 14.5 Trademarks
    6. 14.6 Electrostatic Discharge Caution
    7. 14.7 术语表
  15. 15Mechanical, Packaging, and Orderable Information

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Current Limit Setting using RILIMIT

Refer to Figure 10-14. The TPS2584x-Q1 can establish current limit by two methods.

  • Using external a single or back-to-back N-Channel MOFETs between CSN/OUT and BUS: a voltage of 0.49 V on the ILIMIT pin initiates current limiting using the external MOSFET by decreasing the LS_GD voltage causing the FET to operate in the saturation region. To protect the MOSFETs from damage a hiccup timer limits the duty cycle to prevent thermal runaway. Refer to the Specifications for MOSFET hiccup timing.
  • Buck average current limit: no MOSFET, CSN/OUT connected to BUS. The LS_GD must be pulled up through a 2.2-kΩ resistor. In this configuration, a voltage of 1 V across RILIMIT on the ILIMIT pin initiates average current limiting of the buck regulator.

The 2-level current limit is described below:

  • With external MOSFET Figure 10-15:
    • Isolating a fault on the USB port from other loads connected to the CSP output of the TPS2584x-Q1. In some applications, it can be useful to power additional circuitry (for example: USB HUB) from the output of the TPS2584x-Q1 and maintain operation of these circuits in the event of a short circuit downstream of the BUS pin. To prevent triggering the MOSFET current limit below the programmed ILIMIT threshold, external circuits must be supplied after the inductor and before the current sense resistor, RSNS.

    • After RSNS and RSET are determined and the full load ISET current is known, the resistor value, RILIMIT, can be determined by:

      Equation 6. GUID-B28A90BE-A333-47EB-B42D-E729EFBA1F88-low.gif

    • In most cases, the recommended voltage across RSNS under current limit must be approximately 50 mV as a compromise between accuracy and power dissipation. While in some application, RILIMIT is the only resistor that can be changed to achieve different current limit. Typical RILIMIT resistors value are listed in Table 10-2 given the condition RSNS = 15 mΩ and RSET = 300 Ω

      Table 10-2 Setting the Current Limit with RILIMIT
      Current-Limit Threshold (mA) RILIMIT (kΩ)
      With External MOSFET Without External MOSFET
      700 26.1 53.6
      1500 12.7 26.1
      1700 11.3 22.6
      2700 7.15 14.7
      3000 6.49 13
      3400 5.62 11.5
      3800 5.11 10.5

  • Buck Average Current Limit Figure 10-16:
    1. CSN/OUT connected directly to BUS, LS_GD must be pulled up through 2.2-kΩ resistor. The TPS2584x-Q1 can operate as a stand-alone USB charging port. In this configuration, the internal buck regulator operates with average current limiting as programmed by the ILIMIT pin, potentially producing less heat compared to N-channel MOSFET current limiting

    2. After RSNS and RSET are determined and the full load ISET current is known, the resistor value RILIMIT can be determined by:

      Equation 7. GUID-3A309388-3B9A-49D5-A55B-DFFADDA77BA5-low.gif

    3. Table 10-2 lists Typical RILIMIT resistors values given the condition RSNS = 15 mΩ and RSET = 300 Ω.

GUID-1DF9D7BD-65D9-4ECD-A1EB-F37295FC87B7-low.gifFigure 10-15 Current Limit With External MOSFET
GUID-103C9FFC-A9B9-418C-B3AC-1C8097228231-low.gifFigure 10-16 Buck Average Current Limit