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  • TPS54231 2-A, 28-V Input, Step-Down DC-DC Converter With Eco-mode™

    • SLUS851D October   2008  – October 2014 TPS54231

      PRODUCTION DATA.  

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  • TPS54231 2-A, 28-V Input, Step-Down DC-DC Converter With Eco-mode™
  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Simplified Schematic
  5. 5 Revision History
  6. 6 Pin Configuration and Functions
  7. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 Handling Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 Switching Characteristics
    7. 7.7 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1  Fixed-Frequency PWM Control
      2. 8.3.2  Voltage Reference (Vref)
      3. 8.3.3  Bootstrap Voltage (BOOT)
      4. 8.3.4  Enable and Adjustable Input Undervoltage Lockout (VIN UVLO)
      5. 8.3.5  Programmable Slow Start Using SS Pin
      6. 8.3.6  Error Amplifier
      7. 8.3.7  Slope Compensation
      8. 8.3.8  Current-Mode Compensation Design
      9. 8.3.9  Overcurrent Protection and Frequency Shift
      10. 8.3.10 Overvoltage Transient Protection
      11. 8.3.11 Thermal Shutdown
    4. 8.4 Device Functional Modes
      1. 8.4.1 Eco-mode™
      2. 8.4.2 Operation With VIN < 3.5 V
      3. 8.4.3 Operation With EN Control
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Switching Frequency
        2. 9.2.2.2 Output Voltage Set Point
        3. 9.2.2.3 Input Capacitors
        4. 9.2.2.4 Output Filter Components
          1. 9.2.2.4.1 Inductor Selection
          2. 9.2.2.4.2 Capacitor Selection
        5. 9.2.2.5 Compensation Components
        6. 9.2.2.6 Bootstrap Capacitor
        7. 9.2.2.7 Catch Diode
        8. 9.2.2.8 Output Voltage Limitations
        9. 9.2.2.9 Power Dissipation Estimate
      3. 9.2.3 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
    3. 11.3 Estimated Circuit Area
    4. 11.4 Electromagnetic Interference (EMI) Considerations
  12. 12Device and Documentation Support
    1. 12.1 Device Support
      1. 12.1.1 Development Support
    2. 12.2 Trademarks
    3. 12.3 Electrostatic Discharge Caution
    4. 12.4 Glossary
  13. 13Mechanical, Packaging, and Orderable Information
  14. IMPORTANT NOTICE
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DATA SHEET

TPS54231 2-A, 28-V Input, Step-Down DC-DC Converter With Eco-mode™

1 Features

  • 3.5- to 28-V Input Voltage Range
  • Adjustable Output Voltage Down to 0.8 V
  • Integrated 80-mΩ High-Side MOSFET Supports up to 2 A Continuous Output Current
  • High Efficiency at Light Loads with a Pulse Skipping Eco-mode™
  • Fixed 570-kHz Switching Frequency
  • Typical 1-μA Shutdown Quiescent Current
  • Adjustable Slow-Start Limits Inrush Currents
  • Programmable UVLO Threshold
  • Overvoltage Transient Protection
  • Cycle-by-Cycle Current Limit, Frequency Fold Back and Thermal Shutdown Protection
  • Available in Easy-to-Use SOIC8 Package
  • Supported by WEBENCH® Software Tool (www.TI.com/WEBENCH)

2 Applications

  • Consumer Applications such as Set-Top Boxes, CPE Equipment, LCD Displays, Peripherals, and Battery Chargers
  • Industrial and Car Audio Power Supplies
  • 5-V, 12-V and 24-V Distributed Power Systems

3 Description

The TPS54231 device is a 2-V, 2-A non-synchronous buck converter that integrates a low RDS(on) high-side MOSFET. To increase efficiency at light loads, a pulse skipping Eco-mode™ feature is automatically activated. Furthermore, the 1-μA shutdown supply current allows the device to be used in battery powered applications. Current mode control with internal slope compensation simplifies the external compensation calculations and reduces component count while allowing the use of ceramic output capacitors. A resistor divider programs the hysteresis of the input undervoltage lockout. An overvoltage transient protection circuit limits voltage overshoots during startup and transient conditions. A cycle-by-cycle current limit scheme, frequency fold back and thermal shutdown protect the device and the load in the event of an overload condition. The TPS54231 device is available in an 8-pin SOIC package that has been internally optimized to improve thermal performance.

Device Information(1)

PART NUMBER PACKAGE BODY SIZE (NOM)
TPS54231 SOIC (8) 4.90 mm × 3.90 mm
  1. For all available packages, see the orderable addendum at the end of the datasheet.

4 Simplified Schematic

app_sch_lus851.gif

Efficiency

eff_il_lvs839.gif

5 Revision History

Changes from C Revision (July 2012) to D Revision

  • Added Handling Ratings table, Feature Description section, Device Functional Modes, Application and Implementation section, Power Supply Recommendations section, Layout section, Device and Documentation Support section, and Mechanical, Packaging, and Orderable Information section. Go

Changes from B Revision (February 2012) to C Revision

  • Added 5.3 to the MAX column of the ELEC CHAR table, section CURRENT LIMITGo
  • Deleted Maximum Power Dissipation versus Junction Temperature graphGo

Changes from A Revision (March 2010) to B Revision

  • Deleted Features Item: For SWIFT™ Documentation, See the TI Website at http://www.ti.com/swiftGo

Changes from * Revision (October 2008) to A Revision

  • Changed the ABSOLUTE MAXIMUM RATINGS table, Input Voltage - EN pin max value From: 5V to 6VGo
  • Added a new table to the Description - For additional design needsGo
  • Changed Equation 9 for calculating ILPPGo
  • Added new Equation 10 for calculating IL(RMS)Go
  • Changed Equation 11 for calculating IL(PK)Go
  • Changed Equation 14 for calculating IOUT(RMS)Go
  • Changed Equation 16 for calculating FPOGo
  • Changed Equation 25 for calculating RZGo
  • Changed Equation 28 for calculating RZGo
  • Changed Equation 29 and Equation 30 for calculating CZ and CP, respectively.Go

6 Pin Configuration and Functions

D Package
8-Pin SOIC
Top View
po2_lvs839.gif

Pin Functions

PIN I/O DESCRIPTION
NO. NAME
1 BOOT O A 0.1-μF bootstrap capacitor is required between the BOOT and PH pins. If the voltage on this capacitor falls below the minimum requirement, the high-side MOSFET is forced to switch off until the capacitor is refreshed.
2 VIN I This pin is the 3.5- to 28-V input supply voltage.
3 EN I This pin is the enable pin. To disable, pull below 1.25 V. Float this pin to enable. Programming the input undervoltage lockout with two resistors is recommended.
4 SS I This pin is slow-start pin. An external capacitor connected to this pin sets the output rise time.
5 VSENSE I This pin is the inverting node of the transconductance (gm) error amplifier.
6 COMP O This pin is the error-amplifier output and input to the PWM comparator. Connect frequency compensation components to this pin.
7 GND — Ground pin
8 PH O The PH pin is the source of the internal high-side power MOSFET.

 
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