SNVS217G May   2004  – September 2015 LM2731

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
      1. 7.1.1 Theory of Operation
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
    4. 7.4 Device Functional Modes
      1. 7.4.1 Shutdown Pin Operation
      2. 7.4.2 Thermal Shutdown
      3. 7.4.3 Current Limit
  8. 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 External Capacitors
        2. 8.2.2.2  Selecting the Output Capacitor
        3. 8.2.2.3  Selecting the Input Capacitor
        4. 8.2.2.4  Feedforward Compensation
        5. 8.2.2.5  Selecting Diodes
        6. 8.2.2.6  Setting the Output Voltage
        7. 8.2.2.7  Switching Frequency
        8. 8.2.2.8  Duty Cycle
        9. 8.2.2.9  Inductance Value
        10. 8.2.2.10 Maximum Switch Current
        11. 8.2.2.11 Calculating Load Current
        12. 8.2.2.12 Design Parameters VSW and ISW
        13. 8.2.2.13 Inductor Suppliers
      3. 8.2.3 Application Curves
    3. 8.3 System Examples
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
    3. 10.3 Thermal Considerations
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Third-Party Products Disclaimer
    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

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1 Features

  • 22-V DMOS FET Switch
  • 1.6-MHz (X Option), 0.6-MHz (Y Option) Switching Frequency
  • Low RDS(ON) DMOS FET
  • Switch Current Up to 1.8 A
  • Wide Input Voltage Range (2.7 V to 14 V)
  • Low Shutdown Current (<1 µA)
  • 5-Lead SOT-23 Package
  • Uses Tiny Capacitors and Inductors
  • Cycle-by-Cycle Current Limiting
  • Internally Compensated

2 Applications

  • White LED Current Sources
  • PDAs and Palm-Top Computers
  • Digital Cameras
  • Portable Phones and Games
  • Local Boost Regulators

3 Description

The LM2731 switching regulators are current-mode boost converters operating at fixed frequencies of 1.6 MHz (X option) and 600 kHz (Y option).

The use of SOT-23 package, made possible by the minimal power loss of the internal 1.8-A switch, and use of small inductors and capacitors result in the highest power density of the industry. The 22-V internal switch makes these solutions perfect for boosting to voltages up to 20 V.

These parts have a logic-level shutdown pin that can reduce quiescent current and extend battery life.

Protection is provided through cycle-by-cycle current limiting and thermal shutdown. Internal compensation simplifies design and reduces component count.

Device Information(1)

PART NUMBER PACKAGE BODY SIZE (NOM)
LM2731 SOT-23 (5) 1.60 mm × 2.90 mm
  1. For all available packages, see the orderable addendum at the end of the data sheet.

Block Diagram

LM2731 20059112.png