SNVS556C April   2008  – January 2016 LM2738

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
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Boost Function
      2. 7.3.2 Soft-Start
      3. 7.3.3 Output Overvoltage Protection
      4. 7.3.4 Undervoltage Lockout
      5. 7.3.5 Current Limit
      6. 7.3.6 Thermal Shutdown
    4. 7.4 Device Functional Modes
      1. 7.4.1 Enable Pin and Shutdown Mode
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1  LM2738X Circuit Example 1
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1 Inductor Selection
          2. 8.2.1.2.2 Input Capacitor
          3. 8.2.1.2.3 Output Capacitor
          4. 8.2.1.2.4 Catch Diode
          5. 8.2.1.2.5 Output Voltage
          6. 8.2.1.2.6 Calculating Efficiency and Junction Temperature
        3. 8.2.1.3 Application Curve
      2. 8.2.2  LM2738X Circuit Example 2
        1. 8.2.2.1 Detailed Design Procedure
        2. 8.2.2.2 Application Curve
      3. 8.2.3  LM2738X Circuit Example 3
        1. 8.2.3.1 Detailed Design Procedure
        2. 8.2.3.2 Application Curve
      4. 8.2.4  LM2738X Circuit Example 4
        1. 8.2.4.1 Detailed Design Procedure
      5. 8.2.5  LM2738X Circuit Example 5
        1. 8.2.5.1 Detailed Design Procedure
      6. 8.2.6  LM2738Y Circuit Example 6
        1. 8.2.6.1 Detailed Design Procedure
        2. 8.2.6.2 Application Curve
      7. 8.2.7  LM2738Y Circuit Example 7
        1. 8.2.7.1 Detailed Design Procedure
        2. 8.2.7.2 Application Curve
      8. 8.2.8  LM2738Y Circuit Example 8
        1. 8.2.8.1 Detailed Design Procedure
        2. 8.2.8.2 Application Curve
      9. 8.2.9  LM2738Y Circuit Example 9
        1. 8.2.9.1 Detailed Design Procedure
        2. 8.2.9.2 Application Curve
      10. 8.2.10 LM2738Y Circuit Example 10
        1. 8.2.10.1 Detailed Design Procedure
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
      1. 10.1.1 WSON Package
    2. 10.2 Layout Example
    3. 10.3 Thermal Considerations
      1. 10.3.1 Silicon Junction Temperature Determination Methods
        1. 10.3.1.1 Method 1
        2. 10.3.1.2 Method 2
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Third-Party Products Disclaimer
    2. 11.2 Documentation Support
      1. 11.2.1 Related Documentation
    3. 11.3 Community 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

1 Features

  • Space-Saving WSON and MSOP-PowerPAD™ Packages
  • 3-V to 20-V Input Voltage Range
  • 0.8-V to 18-V Output Voltage Range
  • 1.5-A Output Current
  • 550-kHz (LM2738Y) and 1.6-MHz (LM2738X) Switching Frequencies
  • 250-mΩ NMOS Switch
  • 400-nA Shutdown Current
  • 0.8-V, 2% Internal Voltage Reference
  • Internal Soft-Start
  • Current-Mode, PWM Operation
  • Thermal Shutdown

2 Applications

  • Local Point of Load Regulation
  • Core Power in HDDs
  • Set-Top Boxes
  • Battery Powered Devices
  • USB Powered Devices
  • DSL Modems

3 Description

The LM2738 regulator is a monolithic, high-frequency, PWM step-down DC-DC converter in an 8-pin WSON or 8-pin MSOP-PowerPAD package. It provides all the active functions for local DC-DC conversion with fast transient response and accurate regulation in the smallest possible PCB area.

With a minimum of external components, the LM2738 is easy to use. The ability to drive 1.5-A loads with an internal 250-mΩ NMOS switch using state-of-the-art 0.5-µm BiCMOS technology results in the best power density available. Switching frequency is internally set to 550 kHz (LM2738Y) or 1.6 MHz (LM2738X), allowing the use of extremely small surface-mount inductors and chip capacitors. Even though the operating frequencies are very high, efficiencies up to 90% are easy to achieve. External enable is included, featuring an ultralow standby current of 400 nA. The LM2738 utilizes current-mode control and internal compensation to provide high-performance regulation over a wide range of operating conditions. Additional features include internal soft-start circuitry to reduce in-rush current, cycle-by-cycle current limit, thermal shutdown, and output over-voltage protection.

Device Information(1)

PART NUMBER PACKAGE BODY SIZE (NOM)
LM2738 WSON (8) 3.00 mm × 3.00 mm
MSOP-PowerPAD (8) 3.00 mm × 3.00 mm
  1. For all available packages, see the orderable addendum at the end of the data sheet.

Typical Application Circuit

LM2738 30049101.gif

Efficiency vs Load Current
VIN = 12 V, VOUT = 3.3 V

LM2738 30049145.png