SLVSFJ9 September   2021 TPS25854-Q1 , TPS25855-Q1

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Description (Continued)
  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  Current Limit and Short Circuit Protection
        1. 10.3.8.1 USB Switch Programmable Current Limit (ILIM)
        2. 10.3.8.2 Cycle-by-Cycle Buck Current Limit
        3. 10.3.8.3 OUT Current Limit
      9. 10.3.9  Cable Compensation
      10. 10.3.10 Thermal Management With Temperature Sensing (TS) and OTSD
      11. 10.3.11 Thermal Shutdown
      12. 10.3.12 FAULT Indication
      13. 10.3.13 USB Specification Overview
      14. 10.3.14 USB Type-C® Basics
        1. 10.3.14.1 Configuration Channel
        2. 10.3.14.2 Detecting a Connection
        3. 10.3.14.3 Plug Polarity Detection
      15. 10.3.15 USB Port Operating Modes
        1. 10.3.15.1 USB Type-C® Mode
        2. 10.3.15.2 Dedicated Charging Port (DCP) Mode
          1. 10.3.15.2.1 DCP BC1.2 and YD/T 1591-2009
          2. 10.3.15.2.2 DCP Divider-Charging Scheme
          3. 10.3.15.2.3 DCP 1.2-V Charging Scheme
        3. 10.3.15.3 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
        9. 11.2.2.9 FAULT, POL, and THERM_WARN Resistor Selection
      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 Receiving Notification of Documentation Updates
    2. 14.2 Support Resources
    3. 14.3 Trademarks
    4. 14.4 Electrostatic Discharge Caution
    5. 14.5 Glossary
  15. 15Mechanical, Packaging, and Orderable Information

10.3.1 Power Down or Undervoltage Lockout

The device is in power down mode if the IN terminal voltage is less than VUVLO. The part is considered dead and all the terminals are high impedance. Once the IN voltage rises above the VUVLO threshold, the IC enters sleep mode or active mode depending on the EN/UVLO voltage.

The voltage on the EN/UVLO pin controls the ON/OFF operation of TPS2585x-Q1. An EN/UVLO pin voltage higher than VEN/UVLO-H is required to start the internal regulator and begin monitoring the CCn lines for a valid Type-C connection. The internal USB monitoring circuitry is on when VIN is within the operation range and the EN/UVLO threshold is cleared. The buck regulator starts to operate, however, the USB ports load switch remain OFF until a valid Type-C detection has been made. This feature ensures the cold socket (0 V) USB Type-C VBUS requirement is met.

The EN/UVLO pin is an input and cannot be left open or floating. The simplest way to enable the operation of the TPS2585x-Q1 is to connect the EN to SENSE. This connection allows self-start-up of the TPS2585x-Q1 when VIN is within the operation range. Note that cannot connect the EN to IN pin directly for self-start-up.

Many applications benefit from the employment of an enable divider RENT and RENB to establish a precision system UVLO level for the TPS2585x-Q1, shown in Figure 10-1. The system UVLO can be used for sequencing, ensuring reliable operation, or supply protection, such as a battery discharge level. To ensure the USB ports VBUS is within the 5-V operating range as required for USB compliance (for the latest USB specifications and requirements, refer to USB.org), TI suggests that the RENT and RENB resistors be chosen such that the TPS2585x-Q1 enables when VIN is approximately 6 V. Considering the drop out voltage of the buck regulator and IR loses in the system, 6 V provides adequate margin to maintain VBUS within USB specifications. If system requirements such as a warm crank (start) automotive scenario require operation with VIN < 6 V, the values of RENT and RENB can be calculated assuming a lower VIN. An external logic signal can also be used to drive EN/UVLO input when a microcontroller is present and it is desirable to enable or disable the USB port remotely for other reasons.

GUID-89E6533F-20B3-4897-A1FA-F6064ED5C2B3-low.gifFigure 10-1 System UVLO by Enable Divider

UVLO configuration using external resistors is governed by the following equations:

Equation 1. GUID-A171A040-E467-4762-A1B8-C35E3BAEBF54-low.gif
Equation 2. GUID-CBEEB275-929D-4114-A9A0-3524C63581CC-low.gif

Example:

VIN(ON) = 6V

RENT = 20 kΩ

Equation 3. RENB = [(VEN-VOUT-H) / (VIN(ON) – VEN)] × RENT

RENB = 5 kΩ

Therefore VIN(OFF) = 5.5 V