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

10.3.9 Cable Compensation

When a load draws current through a long or thin wire, there is an IR drop that reduces the voltage delivered to the load. In the vehicle from the voltage regulator output VOUT to VBUS (input voltage of portable device), the total resistance of PCB trace, connector, and cable resistances causes an IR drop at the portable device input, so the charging current of most portable devices is less than their expected maximum charging current. The voltage drop shows in Figure 10-8.

GUID-9D25F8F9-174A-454A-AB25-2C7C2A59B966-low.gifFigure 10-8 Voltage Drop

To handle this case, TPS2585x-Q1 builds in the cable compensation function, which increases the voltage at the SENSE pin to compensate the IR drop in the charging path according to the gain set by RIMON, to maintain a fairly constant output voltage at the load-side voltage.

TPS2585x-Q1 use the switch current-sense output voltage to compensate for the line drop voltage. The cable compensation amplitude increases linearly as the load current increases. It also has an upper limit that the maximum cable compensation voltage is 400 mV, the voltage at USB port clamps below 5.5 V. The cable compensation voltage is programmable through an external resistor at IMON pin. RIMON is then chosen by RIMON = ΔVIMON × 1000 / (IBUS × 0.0169), where ΔVOUT is the desired cable droop compensation voltage at full load. See below Table 10-3 and Figure 10-9.

Table 10-3 TPS2585x-Q1 Cable Compensation Setting
Resistor at IMON pinCable Compensation Voltage at 2.4 A
RIMON = 0 Ω0
RIMON = 0.976 KΩ39.5 mV
RIMON = 2.94 KΩ119 mV
RIMON = 4.99 KΩ202 mV
RIMON = 6.98 KΩ283 mV
RIMON = 8.87 KΩ360 mV
RIMON = 9.76 KΩ396 mV
GUID-D5C47DC7-BD7A-4417-9815-2ED2C6C7BCCF-low.pngFigure 10-9 TPS2585x-Q1 Cable Compensation