SLUSDA4B February   2019  – October 2019 TPS562231

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Simplified Schematic
      2.      TPS562231 Efficiency
  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 Adaptive On-Time Control and PWM Operation
      2. 7.3.2 Soft Start and Pre-Biased Soft Start
      3. 7.3.3 Over Current and Short Circuit Protection
      4. 7.3.4 Undervoltage Lockout (UVLO) Protection
      5. 7.3.5 Thermal Shutdown
    4. 7.4 Device Functional Modes
      1. 7.4.1 Shutdown Mode
      2. 7.4.2 Continuous Conduction Mode (CCM)
      3. 7.4.3 Pulse Skip Mode (PSM, TPS562231)
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Output Voltage Resistors Selection
        2. 8.2.2.2 Output Filter Selection
        3. 8.2.2.3 Input Capacitor Selection
        4. 8.2.2.4 Bootstrap Capacitor Selection
      3. 8.2.3 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 Device Support
    2. 11.2 Receiving Notification of Documentation Updates
    3. 11.3 Community Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

8.2.2.1 Output Voltage Resistors Selection

The output voltage is set with a resistor divider from the output node to the FB pin. 1% tolerance or better divider resistors is recommended. Start by using Equation 2 to calculate VOUT.

To improve efficiency at very light loads consider using larger value resistors, too high of resistance will be more susceptible to noise and voltage errors from the FB input current will be more noticeable.

Equation 2. TPS562231 eq-02-SLUSD65.gif

Choose the value of RFBB to be 10 kΩ. With the desired output voltage set to 3.3 V and the VREF = 0.6 V, the RFBT value can then be calculated using Equation 2. The formula yields to a value 45.3 kΩ of RFBT.