SLVSD01B September   2015  – May 2019 TPS57140-EP

PRODUCTION DATA.  

  1. Features
  2. Applications
  3. Description
    1.     Device Images
      1.      Simplified Schematic
      2.      Efficiency vs Load Current
  4. Revision History
  5. Pin Configuration and Functions
    1.     Pin Functions
  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. 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  Bootstrap Voltage (Boot)
      4. 7.3.4  Low-Dropout Operation
      5. 7.3.5  Error Amplifier
      6. 7.3.6  Voltage Reference
      7. 7.3.7  Adjusting the Output Voltage
      8. 7.3.8  Enable and Adjusting UVLO
      9. 7.3.9  Slow-Start or Tracking Pin (SS/TR)
      10. 7.3.10 Overload Recovery Circuit
      11. 7.3.11 Constant Switching Frequency and Timing Resistor (RT/CLK Pin)
      12. 7.3.12 Overcurrent Protection and Frequency Shift
      13. 7.3.13 Selecting the Switching Frequency
      14. 7.3.14 How to Interface to RT/CLK Pin
      15. 7.3.15 Power Good (PWRGD Pin)
      16. 7.3.16 Overvoltage Transient Protection (OVTP)
      17. 7.3.17 Thermal Shutdown
      18. 7.3.18 Small-Signal Model for Loop Response
      19. 7.3.19 Simple Small-Signal Model for Peak-Current-Mode Control
      20. 7.3.20 Small-Signal Model for Frequency Compensation
    4. 7.4 Device Functional Modes
      1. 7.4.1 Sequencing
      2. 7.4.2 Pulse-Skip Eco-mode Control Scheme
  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  Selecting the Switching Frequency
        2. 8.2.2.2  Output Inductor Selection (LO)
        3. 8.2.2.3  Output Capacitor
        4. 8.2.2.4  Catch Diode
        5. 8.2.2.5  Input Capacitor
        6. 8.2.2.6  Slow-Start Capacitor
        7. 8.2.2.7  Bootstrap Capacitor Selection
        8. 8.2.2.8  UVLO Set Point
        9. 8.2.2.9  Output Voltage and Feedback Resistors Selection
        10. 8.2.2.10 Compensation
      3. 8.2.3 Application Curves
  9. Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
    3. 10.3 Power-Dissipation Estimate
  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

Small-Signal Model for Frequency Compensation

The TPS57140-EP uses a transconductance amplifier for the error amplifier and readily supports three of the commonly-used frequency compensation circuits. Figure 41 shows compensation circuits Type 2A, Type 2B, and Type 1. Type 2 circuits are most likely used in high-bandwidth power-supply designs using low-ESR output capacitors. Power-supply designs with high-ESR aluminum electrolytic or tantalum capacitors likely use the Type 1 circuit. Equation 14 and Equation 15 show how to relate the frequency response of the amplifier to the small-signal model in Figure 41. Modeling of the open-loop gain and bandwidth uses the RO and CO shown in Figure 41. See Application and Implementation for a design example using a Type 2A network with a low-ESR output capacitor.

Equation 14 through Equation 23 are a reference for those who prefer to compensate using the preferred methods. Those who prefer to use a prescribed method must use the method outlined in Application and Implementation or use switched information.

TPS57140-EP f_comp_lvs795.gifFigure 41. Types of Frequency Compensation
TPS57140-EP typ_2a_2b_lvs795.gifFigure 42. Frequency Response of the Type 2A and Type 2B Frequency Compensation
Equation 14. TPS57140-EP eq18_lvs795.gif
Equation 15. TPS57140-EP eq19_lvs795.gif
Equation 16. TPS57140-EP q_ea_lvs795.gif
Equation 17. TPS57140-EP eq21_lvs795.gif
Equation 18. TPS57140-EP eq22_lvs795.gif
Equation 19. TPS57140-EP q_p1_lvs795.gif
Equation 20. TPS57140-EP q_z1_lvs795.gif
Equation 21. TPS57140-EP eq25_lvs795.gif
Equation 22. TPS57140-EP eq26_lvs795.gif
Equation 23. TPS57140-EP eq27_lvs795.gif