SNVS008L September   1998  – June 2016 LM2671

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Description (continued)
  6. 6 Pin Configuration and Functions
  7. 7 Specifications
    1. 7.1  Absolute Maximum Ratings
    2. 7.2  ESD Ratings
    3. 7.3  Recommended Operating Conditions
    4. 7.4  Thermal Information
    5. 7.5  Electrical Characteristics - 3.3 V
    6. 7.6  Electrical Characteristics - 5 V
    7. 7.7  Electrical Characteristics - 12 V
    8. 7.8  Electrical Characteristics - Adjustable
    9. 7.9  Electrical Characteristics - All Output Voltage Versions
    10. 7.10 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 Switch Output
      2. 8.3.2 Input
      3. 8.3.3 C Boost
      4. 8.3.4 Ground
      5. 8.3.5 Sync
      6. 8.3.6 Feedback
      7. 8.3.7 ON/OFF
    4. 8.4 Device Functional Modes
      1. 8.4.1 Shutdown Mode
      2. 8.4.2 Active Mode
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Applications
      1. 9.2.1 Fixed Output Voltage Version
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
          1. 9.2.1.2.1 Inductor Selection (L1)
          2. 9.2.1.2.2 Output Capacitor Selection (COUT)
          3. 9.2.1.2.3 Catch Diode Selection (D1)
          4. 9.2.1.2.4 Input Capacitor (CIN)
          5. 9.2.1.2.5 Boost Capacitor (CB)
          6. 9.2.1.2.6 Soft-Start Capacitor (CSS) - Optional
          7. 9.2.1.2.7 Frequency Synchronization (optional)
        3. 9.2.1.3 Application Curves
      2. 9.2.2 Adjustable Output Voltage Version
        1. 9.2.2.1 Design Requirements
        2. 9.2.2.2 Detailed Design Procedure
          1. 9.2.2.2.1 Programming Output Voltage
          2. 9.2.2.2.2 Inductor Selection (L1)
          3. 9.2.2.2.3 Output Capacitor Selection (COUT)
          4. 9.2.2.2.4 Catch Diode Selection (D1)
          5. 9.2.2.2.5 Input Capacitor (CIN)
          6. 9.2.2.2.6 Boost Capacitor (CB)
        3. 9.2.2.3 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Examples
  12. 12Device and Documentation Support
    1. 12.1 Documentation Support
      1. 12.1.1 Related Documentation
    2. 12.2 Receiving Notification of Documentation Updates
    3. 12.3 Community Resources
    4. 12.4 Trademarks
    5. 12.5 Electrostatic Discharge Caution
    6. 12.6 Glossary
  13. 13Mechanical, Packaging, and Orderable Information
    1. 13.1 DAP (WSON Package)

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

11 Layout

11.1 Layout Guidelines

Layout is very important in switching regulator designs. Rapidly switching currents associated with wiring inductance can generate voltage transients which can cause problems. For minimal inductance and ground loops, the wires indicated by heavy lines (in Figure 15 and Figure 21) must be wide printed-circuit traces and must be kept as short as possible. For best results, external components must be placed as close to the switcher IC as possible using ground plane construction or single point grounding.

If open core inductors are used, take special care as to the location and positioning of this type of inductor. Allowing the inductor flux to intersect sensitive feedback, IC ground path, and COUT wiring can cause problems.

When using the adjustable version, take special care as to the location of the feedback resistors and the associated wiring. Physically place both resistors near the IC, and route the wiring away from the inductor, especially an open core type of inductor.

11.2 Layout Examples

LM2671 10004239.png
CIN = 15-μF, 25-V Solid Tantalum Sprague, 594D series
COUT = 68-μF, 10-V Solid Tantalum Sprague, 594D series
D1 = 1-A, 40-V Schottky Rectifier, surface mount
L1 = 47-μH, L13 Coilcraft DO3308
CB = 0.01-μF, 50-V ceramic
Figure 27. Typical Surface Mount PCB Layout, Fixed Output (4x Size)
LM2671 10004240.png
CIN = 15 μF, 50 V Solid Tantalum Sprague, 594D series
COUT = 33 μF, 25 V Solid Tantalum Sprague, 594D series
D1 = 1-A, 40-V Schottky Rectifier, surface mount
L1 = 100-μH, L20 Coilcraft DO3316
CB = 0.01-μF, 50-V ceramic
R1 = 1 kΩ, 1%
R2 = Use formula in Detailed Design Procedure
Figure 28. Typical Surface Mount PCB Layout, Adjustable Output (4x Size)