SNVS136L September   1998  – June 2016 LM2672

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
    11. 7.11 Typical Characteristics - Fixed Output Voltage Versions
  8. 8 Parameter Measurement Information
  9. 9 Detailed Description
    1. 9.1 Overview
    2. 9.2 Functional Block Diagram
    3. 9.3 Feature Description
      1. 9.3.1 Switch Output
      2. 9.3.2 C Boost
      3. 9.3.3 SYNC
      4. 9.3.4 Feedback
    4. 9.4 Device Functional Modes
      1. 9.4.1 ON/OFF
      2. 9.4.2 Shutdown Mode
      3. 9.4.3 Active Mode
  10. 10Application and Implementation
    1. 10.1 Application Information
    2. 10.2 Typical Applications
      1. 10.2.1 Typical Application for Fixed Output Voltage Versions
        1. 10.2.1.1 Design Requirements
        2. 10.2.1.2 Detailed Design Procedure
          1. 10.2.1.2.1 Inductor Selection (L1)
          2. 10.2.1.2.2 Output Capacitor Selection (COUT)
          3. 10.2.1.2.3 Catch Diode Selection (D1)
          4. 10.2.1.2.4 Input Capacitor (CIN)
          5. 10.2.1.2.5 Boost Capacitor (CB)
          6. 10.2.1.2.6 Soft-Start Capacitor (CSS, Optional)
          7. 10.2.1.2.7 Frequency Synchronization (Optional)
        3. 10.2.1.3 Application Curves
      2. 10.2.2 Typical Application for Adjustable Output Voltage Versions
        1. 10.2.2.1 Design Requirements
        2. 10.2.2.2 Detailed Design Procedure
          1. 10.2.2.2.1 Programming Output Voltage
          2. 10.2.2.2.2 Inductor Selection (L1)
          3. 10.2.2.2.3 Output Capacitor SeIection (COUT)
          4. 10.2.2.2.4 Catch Diode Selection (D1)
          5. 10.2.2.2.5 Input Capacitor (CIN)
          6. 10.2.2.2.6 Boost Capacitor (CB)
        3. 10.2.2.3 Application Curve
  11. 11Power Supply Recommendations
  12. 12Layout
    1. 12.1 Layout Guidelines
      1. 12.1.1 WSON Package Devices
    2. 12.2 Layout Examples
  13. 13Device and Documentation Support
    1. 13.1 Documentation Support
      1. 13.1.1 Related Documentation
    2. 13.2 Receiving Notification of Documentation Updates
    3. 13.3 Community Resources
    4. 13.4 Trademarks
    5. 13.5 Electrostatic Discharge Caution
    6. 13.6 Glossary
  14. 14Mechanical, Packaging, and Orderable Information
    1. 14.1 DAP (WSON Package)

封装选项

机械数据 (封装 | 引脚)
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订购信息

12 Layout

12.1 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 19) 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.

This is the ground reference connection for all components in the power supply. In fast-switching, high-current applications such as those implemented with the LM2672, TI recommends that a broad ground plane be used to minimize signal coupling throughout the circuit.

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.

12.1.1 WSON Package Devices

The LM2672 is offered in the 16-pin WSON surface mount package to allow for increased power dissipation compared to the 8-pin SOIC and PDIP.

The Die Attach Pad (DAP) can and must be connected to PCB Ground plane/island. For CAD and assembly guidelines, refer to AN-1187 Leadless Leadframe Package (LLP).

12.2 Layout Examples

LM2672 1293439.png
CIN = 15-μF, 50-V, solid tantalum Sprague 594D series
COUT = 68-μF, 16-V, solid tantalum Sprague 594D series
D1 = 1-A, 40-V Schottky rectifier, surface mount
L1 = 33-μH, L23, coilcraft DO3316
CB = 0.01-μF, 50-V ceramic
Figure 28. Typical Surface Mount PC Board Layout, Fixed Output
LM2672 1293440.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 = 68-μH, L30, coilcraft DO3316
CB = 0.01-μF, 50-V ceramic
R1 = 1k, 1%, R2: use formula in Detailed Design Procedure
Figure 29. Typical Surface Mount PC Board Layout, Adjustable Output