SNVS656D September   2010  – October 2016 LM3492 , LM3492-Q1

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
    6. 7.6 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 Switching Frequency
      2. 8.3.2 LDO Regulator
      3. 8.3.3 Enable and Disable
      4. 8.3.4 Current Limit
      5. 8.3.5 Thermal Protection
      6. 8.3.6 Dynamic Headroom Control, Over-Ride, and Soft-Start
      7. 8.3.7 Current Regulator
      8. 8.3.8 Output Voltage Feedback
      9. 8.3.9 Bidirectional Communication Pin
        1. 8.3.9.1 Power-Good Indication
        2. 8.3.9.2 Overtemperature Indication
        3. 8.3.9.3 Output Current Undervoltage Indication
        4. 8.3.9.4 Switching Frequency Tuning
    4. 8.4 Device Functional Modes
    5. 8.5 Programming
      1. 8.5.1 Output Current Overvoltage Indication
      2. 8.5.2 COMM Pin Bit Pattern
      3. 8.5.3 Channel 1 Disable
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 RFB1, RFB2, and CFB
        2. 9.2.2.2 L1
        3. 9.2.2.3 D1
        4. 9.2.2.4 CIN and COUT
        5. 9.2.2.5 CVCC
        6. 9.2.2.6 CCDHC
        7. 9.2.2.7 RRT and RIREF
        8. 9.2.2.8 RCOMM
      3. 9.2.3 Application Curve
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Documentation Support
      1. 12.1.1 Related Documentation
    2. 12.2 Related Links
    3. 12.3 Receiving Notification of Documentation Updates
    4. 12.4 Community Resources
    5. 12.5 Trademarks
    6. 12.6 Electrostatic Discharge Caution
    7. 12.7 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

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11 Layout

11.1 Layout Guidelines

The layout of the printed-circuit board is critical to optimize the performance of the LM3492/-Q1 device application circuit. In general, external components should be placed as close to the device and each other as possible to make copper traces short and direct. In particular, components of the boost converter CIN, L1, D1, COUT, and the LM3492/-Q1 device should be closed. Also, the output feedback capacitor CFB should be closed to the output capacitor COUT. The ground plane connecting the GND, PGND, and LGND pins and the exposed pad of the device and the ground connection of the CIN and COUT should be placed on the same copper layer.

Good heat dissipation helps optimize the performance of the device. The ground plane should be used to connect the exposed pad of the device, which is internally connected to the device die substrate. The area of the ground plane should be extended as much as possible on the same copper layer around the device. Using numerous vias beneath the exposed pad to dissipate heat of the device to another copper layer is also a good practice.

11.2 Layout Example

LM3492 LM3492-Q1 slusc65_layout.gif Figure 28. Layout Recommendation