SLVSB14B October   2011  – February 2016 TPS54821

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and 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 Continuous Current Mode Operation (CCM)
      3. 7.3.3 VIN and Power VIN Pins (VIN and PVIN)
      4. 7.3.4 Voltage Reference
      5. 7.3.5 Adjusting the Output Voltage
      6. 7.3.6 Safe Start-up into Pre-Biased Outputs
      7. 7.3.7 Error Amplifier
      8. 7.3.8 Slope Compensation
    4. 7.4 Device Functional Modes
      1. 7.4.1  Enable and Adjusting Undervoltage Lockout
      2. 7.4.2  Adjustable Switching Frequency and Synchronization (RT/CLK)
      3. 7.4.3  Adjustable Switching Frequency (RT Mode)
      4. 7.4.4  Synchronization (CLK mode)
      5. 7.4.5  Slow Start (SS/TR)
      6. 7.4.6  Power Good (PWRGD)
      7. 7.4.7  Bootstrap Voltage (BOOT) and Low Dropout Operation
      8. 7.4.8  Sequencing (SS/TR)
      9. 7.4.9  Output Overvoltage Protection (OVP)
      10. 7.4.10 Overcurrent Protection
      11. 7.4.11 Thermal Shutdown
      12. 7.4.12 Small Signal Model for Loop Response
      13. 7.4.13 Simple Small Signal Model for Peak Current Mode Control
      14. 7.4.14 Small Signal Model for Frequency Compensation
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Parameters
      2. 8.2.2 Design Guide - Step-By-Step Design Procedure
        1. 8.2.2.1  Typical Application Schematic
        2. 8.2.2.2  Operating Frequency
        3. 8.2.2.3  Output Inductor Selection
        4. 8.2.2.4  Output Capacitor Selection
        5. 8.2.2.5  Input Capacitor Selection
        6. 8.2.2.6  Slow Start Capacitor Selection
        7. 8.2.2.7  Bootstrap Capacitor Selection
        8. 8.2.2.8  Under Voltage Lockout Set Point
        9. 8.2.2.9  Output Voltage Feedback Resistor Selection
          1. 8.2.2.9.1 Minimum Output Voltage
        10. 8.2.2.10 Compensation Component Selection
        11. 8.2.2.11 Fast Transient Considerations
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 PCB Layout Guidelines
    2. 10.2 Layout Example
      1. 10.2.1 Estimated Circuit Area
  11. 11Device and Documentation Support
    1. 11.1 Trademarks
    2. 11.2 Electrostatic Discharge Caution
    3. 11.3 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

9 Power Supply Recommendations

The TPS54821 is designed to operate from an input voltage supply range between 4.5 V and 17 V. This supply voltage must be well regulated. Power supplies must be well bypassed for proper electrical performance. This includes a minimum of one 4.7 μF (after de-rating) ceramic capacitor, type X5R or better from PVIN to GND, and from VIN to GND. Additional local ceramic bypass capacitance may be required in systems with small input ripple specifications, in addition to bulk capacitance if the TPS54821 device is located more than a few inches away from its input power supply. In systems with an auxiliary power rail available, the power stage input, PVIN, and the analog power input, VIN, may operate from separate input supplies. See Figure 45 (layout recommendation) for recommended bypass capacitor placement.