SNVS589N September   2008  – November 2014 LM22671 , LM22671-Q1

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 Handling Ratings: LM22671
    3. 6.3 Handling Ratings: LM22671-Q1
    4. 6.4 Recommended Operating Conditions
    5. 6.5 Thermal Information
    6. 6.6 Electrical Characteristics
    7. 6.7 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 Precision Enable and UVLO
      2. 7.3.2 Soft-Start
      3. 7.3.3 Switching Frequency Adjustment and Synchronization
      4. 7.3.4 Self-Synchronization
      5. 7.3.5 Boot-Strap Supply
      6. 7.3.6 Internal Loop Compensation
    4. 7.4 Device Functional Modes
      1. 7.4.1 Current Limit
      2. 7.4.2 Thermal Shutdown
      3. 7.4.3 Duty-Cycle Limits
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Output Voltage Divider Selection
      2. 8.1.2 Power Diode
    2. 8.2 Typical Application
      1. 8.2.1 Typical Buck Regulator Application
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1 External Components
          2. 8.2.1.2.2 Inductor
          3. 8.2.1.2.3 Input Capacitor
          4. 8.2.1.2.4 Output Capacitor
          5. 8.2.1.2.5 Boot-Strap Capacitor
        3. 8.2.1.3 Application Curves
  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 Documentation Support
      1. 11.1.1 Related Documentation
    2. 11.2 Related Links
    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

1 Features

  • Wide Input Voltage Range: 4.5 V to 42 V
  • Internally Compensated Voltage Mode Control
  • Stable with Low ESR Ceramic capacitors
  • 200 mΩ N-Channel MOSFET
  • Output Voltage Options:
    -ADJ (Outputs as Low as 1.285 V)
    -5.0 (Output Fixed to 5 V)
  • ±1.5% Feedback Reference Accuracy
  • 500 kHz Default Switching Frequency
  • Adjustable Switching Frequency and Synchronization
  • –40°C to 125°C Operating Junction
    Temperature Range
  • Precision Enable Pin
  • Integrated Boot-Strap Diode
  • Adjustable Soft-Start
  • Fully WEBENCH® Enabled
  • LM22671-Q1 is an Automotive Grade Product
    that is AEC-Q100 Grade 1 Qualified (–40°C to +125°C Operating Junction Temperature)
  • SO PowerPAD™ (Exposed Pad)

2 Applications

  • Industrial Control
  • Telecom and Datacom Systems
  • Embedded Systems
  • Conversions from Standard 24 V, 12 V and 5 V Input Rails

Simplified Application Schematic

30076801.gif

3 Description

The LM22671 switching regulator provides all of the functions necessary to implement an efficient high voltage step-down (buck) regulator using a minimum of external components. This easy to use regulator incorporates a 42 V N-channel MOSFET switch capable of providing up to 500 mA of load current. Excellent line and load regulation along with high efficiency (> 90%) are featured. Voltage mode control offers short minimum on-time, allowing the widest ratio between input and output voltages. Internal loop compensation means that the user is free from the tedious task of calculating the loop compensation components. Fixed 5 V output and adjustable output voltage options are available. The default switching frequency is set at 500 kHz allowing for small external components and good transient response. In addition, the frequency can be adjusted over a range of 200 kHz to 1 MHz with a single external resistor. The internal oscillator can be synchronized to a system clock or to the oscillator of another regulator. A precision enable input allows simplification of regulator control and system power sequencing. In shutdown mode the regulator draws only 25 µA (typ). An adjustable soft-start feature is provided through the selection of a single external capacitor. The LM22671 device also has built-in thermal shutdown and current limiting to protect against accidental overloads.

The LM22671 device is a member of Texas Instruments' SIMPLE SWITCHER® family. The SIMPLE SWITCHER concept provides for an easy to use complete design using a minimum number of external components and the TI WEBENCH design tool. TI's WEBENCH tool includes features such as external component calculation, electrical simulation, thermal simulation, and Build-It boards for easy design-in.

Device Information(1)

PART NUMBER PACKAGE BODY SIZE (NOM)
LM22671 HSOP (8) 4.89 mm x 3.90 mm
LM22671-Q1
  1. For all available packages, see the orderable addendum at the end of the data sheet.