SLUSBP5E March   2014  – July 2018 TPS92601-Q1 , TPS92602-Q1

UNLESS OTHERWISE NOTED, this document contains PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1. 3.1 Typical Schematic
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
    1.     Pin Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Fixed-Frequency PWM Control
      2. 7.3.2 Slope-Compensation Output Current
      3. 7.3.3 Boost-Current Limit
      4. 7.3.4 Oscillator and PLL
      5. 7.3.5 Control Loop Compensation
      6. 7.3.6 LED Open-Circuit Detection
      7. 7.3.7 Output Short-Circuit and Overcurrent Detection
      8. 7.3.8 Measuring LED Current During a Non-Failure Condition
      9. 7.3.9 LED Dimming Options
        1. 7.3.9.1 Analog Dimming
        2. 7.3.9.2 PWM Dimming
    4. 7.4 Device Functional Modes
      1. 7.4.1 Undervoltage and Overvoltage Shutdown
      2. 7.4.2 Overtemperature Shutdown
      3. 7.4.3 Device State Diagram
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 Boost Regulator With Separate or Paralleled Channels
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1  Switching Frequency
          2. 8.2.1.2.2  Maximum Output-Current Set Point
          3. 8.2.1.2.3  Output Overvoltage-Protection Set Point
          4. 8.2.1.2.4  Duty Cycle Estimation
          5. 8.2.1.2.5  Inductor Selection
          6. 8.2.1.2.6  Rectifier Diode Selection
          7. 8.2.1.2.7  Output Capacitor Selection
          8. 8.2.1.2.8  Input Capacitor Selection
          9. 8.2.1.2.9  Current Sense and Current Limit
          10. 8.2.1.2.10 Switching MOSFET Selection
          11. 8.2.1.2.11 Loop Compensation
        3. 8.2.1.3 Application Curves
      2. 8.2.2 Boost-to-Battery Regulator
        1. 8.2.2.1 Design Requirements
        2. 8.2.2.2 Detailed Design Procedure
          1. 8.2.2.2.1  Switching Frequency
          2. 8.2.2.2.2  Maximum Output-Current Set Point
          3. 8.2.2.2.3  Output Overvoltage-Protection Set Point
          4. 8.2.2.2.4  Duty Cycle Estimation
          5. 8.2.2.2.5  Inductor Selection
          6. 8.2.2.2.6  Rectifier Diode Selection
          7. 8.2.2.2.7  Output Capacitor Selection
          8. 8.2.2.2.8  Input Capacitor Selection
          9. 8.2.2.2.9  Current Sense and Current Limit
          10. 8.2.2.2.10 Switching MOSFET Selection
          11. 8.2.2.2.11 Loop Compensation
        3. 8.2.2.3 TPS92602y-Q1 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Related Links
    2. 11.2 Trademarks
    3. 11.3 Electrostatic Discharge Caution
    4. 11.4 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

8.2.1.2.6 Rectifier Diode Selection

The circuit uses a low-forward-voltage-drop Schottky diode as a rectifier diode to reduce power dissipation and improve efficiency. Use 80% derating for the diode on VOUTx to allow for for ringing on the switch node. Equation 24 gives the rectifier-diode minimum reverse-breakdown voltage.

Equation 24. TPS92601-Q1 TPS92602-Q1 eq21_Vbr_SLUSBP5.gif

The diode must have a reverse-breakdown voltage greater than 45 V. Equation 25 and Equation 26 estimate the rectifier diode peak and average currents.

Equation 25. TPS92601-Q1 TPS92602-Q1 eq22_IDavg_SLUSBP5.gif
Equation 26. TPS92601-Q1 TPS92602-Q1 eq23_IDpeak_SLUSBP5.gif

For this design, average current is 1 A and peak current is 5.26 A.

Equation 27 estimates the power dissipation in the diode.

Equation 27. TPS92601-Q1 TPS92602-Q1 eq24_PDmax_SLUSBP5.gif

For this design, the maximum power dissipation is estimated as 0.5 W. After reviewing 45-V and 60-V Schottky diodes, the selection is the 30BQ060PbF diode, Schottky, 60 V, 3 A, SMC. This diode has a forward voltage drop of 0.5 V at 1 A, so the conduction power dissipation is approximately 500 mW, less than half its rated power dissipation.