SLVSDC9B November   2016  – November 2019 TPS54824

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
    1.     Simplified Schematic
  3. 3 Description
    1.     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 Switching Characteristics
    7. 6.7 Timing Requirements
    8. 6.8 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  Continuous Conduction Mode Operation (CCM)
      3. 7.3.3  VIN Pins and VIN UVLO
      4. 7.3.4  Voltage Reference and Adjusting the Output Voltage
      5. 7.3.5  Error Amplifier
      6. 7.3.6  Enable and Adjustable UVLO
      7. 7.3.7  Soft Start and Tracking
      8. 7.3.8  Safe Start-up into Pre-Biased Outputs
      9. 7.3.9  Power Good
      10. 7.3.10 Sequencing (SS/TRK)
      11. 7.3.11 Adjustable Switching Frequency (RT Mode)
      12. 7.3.12 Synchronization (CLK Mode)
      13. 7.3.13 Bootstrap Voltage and 100% Duty Cycle Operation (BOOT)
      14. 7.3.14 Output Overvoltage Protection (OVP)
      15. 7.3.15 Overcurrent Protection
        1. 7.3.15.1 High-side MOSFET Overcurrent Protection
        2. 7.3.15.2 Low-side MOSFET Overcurrent Protection
    4. 7.4 Device Functional Modes
  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  Switching Frequency
        2. 8.2.2.2  Output Inductor Selection
        3. 8.2.2.3  Output Capacitor
        4. 8.2.2.4  Input Capacitor
        5. 8.2.2.5  Output Voltage Resistors Selection
        6. 8.2.2.6  Soft-start Capacitor Selection
        7. 8.2.2.7  Undervoltage Lockout Set Point
        8. 8.2.2.8  Bootstrap Capacitor Selection
        9. 8.2.2.9  PGOOD Pull-up Resistor
        10. 8.2.2.10 Compensation
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
    3. 10.3 Alternate Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Receiving Notification of Documentation Updates
    2. 11.2 Community Resources
    3. 11.3 Trademarks
    4. 11.4 Electrostatic Discharge Caution
    5. 11.5 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

7.3.4 Voltage Reference and Adjusting the Output Voltage

The voltage reference system produces a precise ±0.85%, 0.6 V voltage reference over temperature by scaling the output of a temperature stable band gap circuit. The output voltage is set with a resistor divider from the output (VOUT) to the FB pin shown in Figure 23. It is recommended to use 1% tolerance or better divider resistors. Start with a fixed value for the bottom resistor in the divider, typically 10 kΩ, then use Equation 1 to calculate the top resistor in the divider. To improve efficiency at light loads consider using larger value resistors. If the values are too high the regulator is more susceptible to noise and voltage errors from the FB input current are noticeable. The minimum output voltage and maximum output voltage can be limited by the minimum on time of the high side MOSFET and bootstrap voltage (BOOT-SW voltage) respectively.

TPS54824 ai_FB_div_slvsdc9.gifFigure 23. FB Resistor Divider
Equation 1. TPS54824 EQ_FBdivider_slvsdc9.gif