SNVSAO6C September   2017  – March 2018 LMZM33603

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
    1.     Simplified Schematic
  3. 3 Description
    1.     Safe Operating Area
  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 Switching Characteristics
    7. 6.7 Typical Characteristics (VIN = 5 V)
    8. 6.8 Typical Characteristics (VIN = 12 V)
    9. 6.9 Typical Characteristics (VIN = 24 V)
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1  Adjusting the Output Voltage
      2. 7.3.2  Feed-Forward Capacitor, CFF
      3. 7.3.3  Output Current vs Output Voltage
      4. 7.3.4  Voltage Dropout
      5. 7.3.5  Switching Frequency (RT)
      6. 7.3.6  Synchronization (SYNC)
      7. 7.3.7  Input Capacitors
      8. 7.3.8  Output Capacitors
      9. 7.3.9  Output On/Off Enable (EN)
      10. 7.3.10 Programmable Undervoltage Lockout (UVLO)
      11. 7.3.11 Power Good (PGOOD)
      12. 7.3.12 Overcurrent Protection (OCP)
      13. 7.3.13 Thermal Shutdown
    4. 7.4 Device Functional Modes
      1. 7.4.1 Active Mode
      2. 7.4.2 Shutdown Mode
  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 Output Voltage Setpoint
        3. 8.2.2.3 Feed-Forward Capacitor (CFF)
        4. 8.2.2.4 Setting the Switching Frequency
        5. 8.2.2.5 Input Capacitors
        6. 8.2.2.6 Output Capacitor Selection
        7. 8.2.2.7 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Examples
    3. 10.3 Theta JA vs PCB Area
    4. 10.4 EMI
      1. 10.4.1 EMI Plots
    5. 10.5 Package Specifications
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Third-Party Products Disclaimer
      2. 11.1.2 Custom Design With WEBENCH® Tools
    2. 11.2 Related Documentation
    3. 11.3 Receiving Notification of Documentation Updates
    4. 11.4 Community Resources
    5. 11.5 Trademarks
    6. 11.6 Electrostatic Discharge Caution
    7. 11.7 Glossary
  12. 12Mechanical, Packaging, and Orderable Information
    1. 12.1 Tape and Reel Information

7.1 Overview

The LMZM33603 is a full-featured, 36-V input, 3-A, synchronous, step-down converter with PWM, MOSFETs, shielded inductor, and control circuitry integrated into a low-profile, overmolded package. The device integration enables small designs, while providing the ability to adjust key parameters to meet specific design requirements. The LMZM33603 provides an output voltage range of 1 V to 18 V. An external resistor divider is used to adjust the output voltage to the desired value. The switching frequency can also be adjusted, by either an external resistor or a sync signal, which allows the LMZM33603 to accommodate a variety of input and output voltage conditions as well as optimize efficiency. The device provides accurate voltage regulation over a wide load range by using a precision internal voltage reference. Input undervoltage lockout is internally set at 3.6 V (typical), but can be adjusted upward using a resistor divider on the EN/SYNC pin of the device. The EN/SYNC pin can also be pulled low to put the device into standby mode to reduce input quiescent current. A power-good signal is provided to indicate when the output is within its nominal voltage range. Thermal shutdown and current limit features protect the device during an overload condition. An 18-pin, QFN package that includes exposed bottom pads provides a thermally enhanced solution for space-constrained applications.