SNVS853E August   2012  – August 2018 LMZ21701

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Simplified Schematic
      2.      Efficiency for VIN = 12 V
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
    1.     Pin 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 Package Construction
    4. 7.4 Feature Description
      1. 7.4.1 Input Undervoltage Lockout
      2. 7.4.2 Enable Input (EN)
      3. 7.4.3 Soft Start and Tracking Function (SS)
      4. 7.4.4 Power Good Function (PG)
      5. 7.4.5 Output Voltage Setting
      6. 7.4.6 Output Current Limit and Output Short Circuit Protection
      7. 7.4.7 Thermal Protection
    5. 7.5 Device Functional Modes
      1. 7.5.1 PWM Mode Operation
      2. 7.5.2 PSM Operation
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Custom Design With WEBENCH® Tools
        2. 8.2.2.2 Input Capacitor (CIN)
        3. 8.2.2.3 Output Capacitor (COUT)
        4. 8.2.2.4 Soft-start Capacitor (CSS)
        5. 8.2.2.5 Power Good Resistor (RPG)
        6. 8.2.2.6 Feedback Resistors (RFBB and RFBT)
      3. 8.2.3 Application Curves
        1. 8.2.3.1 VOUT = 1.2 V
        2. 8.2.3.2 VOUT = 1.8 V
        3. 8.2.3.3 VOUT = 2.5 V
        4. 8.2.3.4 VOUT = 3.3 V
        5. 8.2.3.5 VOUT = 5.0 V
    3. 8.3 Do's and Don'ts
  9. 9 Power Supply Recommendations
    1. 9.1 Voltage Range
    2. 9.2 Current Capability
    3. 9.3 Input Connection
      1. 9.3.1 Voltage Drops
      2. 9.3.2 Stability
  10. 10Layout
    1. 10.1 Layout Guidelines
      1. 10.1.1 Minimize the High di/dt Loop Area
      2. 10.1.2 Protect the Sensitive Nodes in the Circuit
      3. 10.1.3 Provide Thermal Path and Shielding
    2. 10.2 Layout Example
      1. 10.2.1 High Density Layout Example for Space Constrained Applications
        1. 10.2.1.1 35 mm² Solution Size (Single Sided)
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Development Support
        1. 11.1.1.1 Custom Design With WEBENCH® Tools
    2. 11.2 Trademarks
    3. 11.3 Electrostatic Discharge Caution
    4. 11.4 Glossary
  12. 12Mechanical, Packaging, and Orderable Information
    1. 12.1 Tape and Reel Information

10.1 Layout Guidelines

The PCB layout is critical for the proper operation of any DC/DC switching converter. Although using modules can simplify the PCB layout process, care should still be taken to minimize the inductance in the high di/dt loops and to protect sensitive nodes. The following guidelines should be followed when designing a board layout with the LMZ21701: