SLUS772G March   2008  – June 2020

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  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  Soft Start
      2. 7.3.2  BP Regulator
      3. 7.3.3  Shutdown (DIS/ EN Pin)
      4. 7.3.4  Minimum On-Time and Off-Time Considerations
      5. 7.3.5  Setting the Oscillator Frequency
      6. 7.3.6  Synchronizing the Oscillator
      7. 7.3.7  Current Sense and Overcurrent
      8. 7.3.8  Current Sense and Subharmonic Instability
      9. 7.3.9  Current Sense Filtering
      10. 7.3.10 Control Loop Considerations
      11. 7.3.11 Gate Drive Circuit
      12. 7.3.12 TPS40211
    4. 7.4 Device Functional Modes
      1. 7.4.1 Operation Near Minimum Input Voltage
      2. 7.4.2 Operation With DIS/ EN Pin
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 12-V to 24-V Nonsynchronous Boost Regulator
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1  Custom Design with WEBENCH Tools
          2. 8.2.1.2.2  Duty Cycle Estimation
          3. 8.2.1.2.3  Inductor Selection
          4. 8.2.1.2.4  Rectifier Diode Selection
          5. 8.2.1.2.5  Output Capacitor Selection
          6. 8.2.1.2.6  Input Capacitor Selection
          7. 8.2.1.2.7  Current Sense and Current Limit
          8. 8.2.1.2.8  Current Sense Filter
          9. 8.2.1.2.9  Switching MOSFET Selection
          10. 8.2.1.2.10 Feedback Divider Resistors
          11. 8.2.1.2.11 Error Amplifier Compensation
          12. 8.2.1.2.12 RC Oscillator
          13. 8.2.1.2.13 Soft-Start Capacitor
          14. 8.2.1.2.14 Regulator Bypass
          15. 8.2.1.2.15 Bill of Materials
        3. 8.2.1.3 Application Curves
      2. 8.2.2 12-V Input, 700-mA LED Driver, Up to 35-V LED String
        1. 8.2.2.1 Design Requirements
        2. 8.2.2.2 Detailed Design Procedure
  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.      65
      3. 11.1.2 Related Devices
      4. 11.1.3 Development Support
        1. 11.1.3.1 Custom Design with WEBENCH Tools
    2. 11.2 Documentation Support
      1. 11.2.1 Related Documentation
    3. 11.3 Related Links
    4. 11.4 Receiving Notification of Documentation Updates
    5. 11.5 Support Resources
    6. 11.6 Trademarks
    7. 11.7 Electrostatic Discharge Caution
    8. 11.8 Glossary
  12. 12Mechanical, Packaging, and Orderable Information
    1.     78

7.1 Overview

The TPS4021x is a peak current-mode control low-side controller with a built in 400-mA gate driver designed to drive n- channel MOSFETs at a fixed frequency. The frequency is adjustable from 35 kHz to 1000 kHz. Small size combined with complete functionality makes the part both versatile and easy to use.

The controller uses a low-value current-sensing resistor in series with the power MOSFET's source connection to detect switching current. When the voltage drop across this resistor exceeds 150 mV, the part enters an hiccup fault mode with a time period set by the external soft-start capacitor.

The TPS40210 uses voltage feedback to an error amplifier that is biased by a precision 700-mV reference. The TPS40211 has a lower 260-mV reference for higher efficiency in LED drive applications. Internal slope compensation eliminates the characteristic sub-harmonic instability of peak current mode control with duty cycles of 50% or greater.

The TPS4021x also incorporates a soft-start feature where the output follows a slowly rising soft-start voltage, preventing output-voltage overshoot. The DIS/ EN disables the TPS40210 putting it in a low quiescent current shutdown mode.