SLVSDG7A April   2016  – April 2021 TPS54202H

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 Timing Requirements
  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  Pulse Skip Mode
      3. 7.3.3  Error Amplifier
      4. 7.3.4  Slope Compensation and Output Current
      5. 7.3.5  Device Enable
      6. 7.3.6  Adjusting Under Voltage Lockout
      7. 7.3.7  Safe Startup into Pre-Biased Outputs
      8. 7.3.8  Voltage Reference
      9. 7.3.9  Adjusting Output Voltage
      10. 7.3.10 Internal Soft-Start
      11. 7.3.11 Bootstrap Voltage (BOOT)
      12. 7.3.12 Overcurrent Protection
        1. 7.3.12.1 High-Side MOSFET Overcurrent Protection
        2. 7.3.12.2 Low-Side MOSFET Overcurrent Protection
      13. 7.3.13 Output Overvoltage Protection (OVP)
      14. 7.3.14 Thermal Shutdown
    4. 7.4 Device Functional Modes
      1. 7.4.1 Normal Operation
      2. 7.4.2 Eco-mode Operation
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 TPS54202H 8-V to 28-V Input, 5-V Output Converter
      2. 8.2.2 Design Requirements
      3. 8.2.3 Detailed Design Procedure
        1. 8.2.3.1 Input Capacitor Selection
        2. 8.2.3.2 Bootstrap Capacitor Selection
        3. 8.2.3.3 Output Voltage Set Point
        4. 8.2.3.4 Enable Pin Setup
        5. 8.2.3.5 Output Filter Components
          1. 8.2.3.5.1 Inductor Selection
          2. 8.2.3.5.2 Output Capacitor Selection
          3. 8.2.3.5.3 Feed-Forward Capacitor
      4. 8.2.4 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
      1. 11.1.1 Third-Party Products Disclaimer
    2. 11.2 Receiving Notification of Documentation Updates
    3. 11.3 Support Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information
8.2.3.5.3 Feed-Forward Capacitor

The TPS54202H device is internally compensated and the internal compensation network is composed of two capacitors and one resister shown on the block diagram. Depending on the VOUT, if the output capacitor COUT is dominated by low ESR (ceramic types) capacitors, it could result in low phase margin. To improve the phase boost an external feedforward capacitor C6 can be added in parallel with R2. C6 is chosen such that phase margin is boosted at the crossover frequency.

Equation 16 for C6 was tested:

Equation 16. GUID-71A591A9-E1B5-4751-82FD-528022DC0678-low.gif

For this design, C6 = 75 pF. C6 is not needed when COUT has high ESR, and C6 calculated from Equation 16 should be reduced with medium ESR. Table 8-2 can be used as a starting point.

Table 8-2 Recommended Component Values
VOUT (V) L (µH) COUT(µF) R2 (kΩ) R3 (kΩ) C6 (pF)
1.8 5.6 66 100 49.9 47
2.5 8.2 44 100 31.6 33
3.3 10 44 100 22.1 56
5 15 44 100 13.3 75
12 22 44 100 5.23 100