SLVSF62B November   2020  – September 2021 TPS25858-Q1 , TPS25859-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  Selectable Output Voltage (VSET)
      9. 10.3.9  Current Limit and Short Circuit Protection
        1. 10.3.9.1 USB Switch Programmable Current Limit (ILIM)
        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 Enable On and Off Control (TPS25859-Q1)
      14. 10.3.14 FAULT Indication (TPS25859-Q1)
      15. 10.3.15 USB Specification Overview
      16. 10.3.16 USB Type-C® Basics
        1. 10.3.16.1 Configuration Channel
        2. 10.3.16.2 Detecting a Connection
      17. 10.3.17 USB Port Operating Modes
        1. 10.3.17.1 USB Type-C® Mode
        2. 10.3.17.2 Dedicated Charging Port (DCP) Mode (TPS25858-Q1 Only)
          1. 10.3.17.2.1 DCP BC1.2 and YD/T 1591-2009
          2. 10.3.17.2.2 DCP Divider-Charging Scheme
          3. 10.3.17.2.3 DCP 1.2-V Charging Scheme
        3. 10.3.17.3 DCP Auto Mode (TPS25858-Q1)
    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 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

10.3.3 Buck Converter

The following operating description of the TPS2585x-Q1 refers to the Functional Block Diagram. The TPS2585x-Q1 integrates a monolithic, synchronous, rectified, step-down, switch-mode converter with internal power MOSFETs and USB current-limit switches with charging ports auto-detection.
The TPS2585x-Q1 offers a compact solution that achieves up to 6.6 A of continuous output current with excellent load and line regulation over a wide input supply range. The TPS2585x-Q1 supplies a regulated output voltage by turning on the high-side (HS) and low-side (LS) NMOS switches with controlled duty cycle. During high-side switch ON time, the SW pin voltage swings up to approximately VIN. The inductor current iL increases with linear slope (VIN – VOUT ) / L. When the HS switch is turned off by the control logic, the LS switch is turned on after an anti-shoot-through dead time. Inductor current discharges through the LS switch with a slope of –VOUT / L. The control parameter of a buck converter is defined as Duty Cycle D = tON / TSW, where tON is the high-side switch ON time and TSW is the switching period, shown in Figure 10-2. The regulator control loop maintains a constant output voltage by adjusting the duty cycle D. In an ideal buck converter, where losses are ignored, D is proportional to the output voltage and inversely proportional to the input voltage: D = VOUT / VIN.

GUID-198D0D36-0279-4BA4-8CB6-761E42CAFD52-low.gifFigure 10-2 SW Node and Inductor Current Waveforms in Continuous Conduction Mode (CCM)

The TPS2585x-Q1 operates in a fixed-frequency, peak-current-mode control to regulate the output voltage. A voltage feedback loop is used to get accurate DC voltage regulation by adjusting the peak current command based on voltage offset. The peak inductor current is sensed from the high-side switch and compared to the peak current threshold to control the ON time of the high-side switch. The voltage feedback loop is internally compensated, which allows for fewer external components, making it easy to design, and provides stable operation with a reasonable combination of output capacitors. The TPS2585x-Q1 operates in FPWM mode for low output voltage ripple, tight output voltage regulation, and constant switching frequency.