SNVSB53C February   2018  – March 2023 LMZM23600

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Device Comparison
  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 System Characteristics
    7. 7.7 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 Control Scheme
      2. 8.3.2 Soft-Start Function
      3. 8.3.3 Enable and External UVLO Function
      4. 8.3.4 Current Limit
      5. 8.3.5 Hiccup Mode
      6. 8.3.6 Power Good (PGOOD) Function
      7. 8.3.7 MODE/SYNC Function
        1. 8.3.7.1 Forced PWM Mode
        2. 8.3.7.2 Auto PFM Mode
        3. 8.3.7.3 Dropout Mode
        4. 8.3.7.4 SYNC Operation
      8. 8.3.8 Thermal Protection
    4. 8.4 Device Functional Modes
      1. 8.4.1 Shutdown
      2. 8.4.2 FPWM Operation
      3. 8.4.3 Auto PFM Mode Operation
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Applications
      1. 9.2.1 Design Requirements
        1. 9.2.1.1 Maximum Input Voltage for VOUT < 2.5 V
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Custom Design With WEBENCH® Tools
        2. 9.2.2.2 Input Capacitor Selection
        3. 9.2.2.3 Output Capacitor Selection
        4. 9.2.2.4 Feedback Voltage Divider for Adjustable Output Voltage Versions
        5. 9.2.2.5 RPU - PGOOD Pullup Resistor
        6. 9.2.2.6 VIN Divider and Enable
      3. 9.2.3 Application Curves
        1. 9.2.3.1 VOUT = 5 V
        2. 9.2.3.2 VOUT = 3.3 V
        3. 9.2.3.3 VOUT = 12 V
        4. 9.2.3.4 VOUT = 15 V
        5. 9.2.3.5 VOUT = 2.5 V
        6. 9.2.3.6 VOUT = 1.2 V and VOUT = 1.8 V
        7. 9.2.3.7 VOUT = 5 V and 3.3 V Fixed Output Options
    3. 9.3 Best Design Practices
    4. 9.4 Power Supply Recommendations
      1. 9.4.1 Supply Voltage Range
      2. 9.4.2 Supply Current Capability
      3. 9.4.3 Supply Input Connections
        1. 9.4.3.1 Voltage Drops
        2. 9.4.3.2 Stability
    5. 9.5 Layout
      1. 9.5.1 Layout Guidelines
        1. 9.5.1.1 Thermal Design
      2. 9.5.2 Layout Examples
  10. 10Device and Documentation Support
    1. 10.1 Device Support
      1. 10.1.1 Third-Party Products Disclaimer
      2. 10.1.2 Development Support
        1. 10.1.2.1 Custom Design With WEBENCH® Tools
    2. 10.2 Documentation Support
      1. 10.2.1 Related Documentation
    3. 10.3 Receiving Notification of Documentation Updates
    4. 10.4 Support Resources
    5. 10.5 Trademarks
    6. 10.6 Electrostatic Discharge Caution
    7. 10.7 Glossary
  11. 11Mechanical, Packaging, and Orderable Information
    1. 11.1 Tape and Reel Information

9.5.1 Layout Guidelines

Good board layout is essential for the proper operation of any switching regulator. A poor layout can ruin an otherwise perfect schematic design. The good news is that it is relatively easy to achieve an optimized layout when using a module because some of the critical nodes for the board layout are internal to the device. To have a good layout with this module, the designer must follow these main objectives:

  1. Minimize the inductance in the switching current path of the converter. The switching current path in the buck converter is formed by the input capacitor and the power switches (for example, MOSFETs). A common mistake in many buck converter layouts is placing the input capacitor far from the IC. This introduces inductance in the switching current path, which leads to high frequency ringing on the switching node, which results in high frequency noise coupled all the way to the output voltage. The input capacitor placement affects the amount of noise on the output in a buck converter. Place the input capacitor as close as possible, right next to the LMZM23600 ensures that the switching current path area is kept to a minimum. This results in the lowest possible inductance in the path of high di/dt current.
  2. Protect any sensitive nodes in the converter design. The feedback node is usually a sensitive area of the converter and needs to be away from any noise sources. The fixed 5-V and 3.3-V output voltage versions of the LMZM23600 have the feedback resistors internal to the device, and the sensitive node is inside the module. However, if the adjustable option is used, then two feedback resistors are required to set the output voltage. A common mistake in many layouts is placing the divider close to the load, far from the device, and then using a long feedback trace back to the regulator. A long feedback trace can potentially pick up noise from other nearby circuits. TI recommends placing the feedback divider as close as possible to the LMZM23600 device so that the feedback node is as small as possible.
  3. Provide enough copper for heat dissipation. The board copper provides a thermal resistance path for the heat to flow out of the package and dissipate into the environment. Place a dog-bone shape of ground (GND) copper under the module for proper heat sinking. Also, place thermal vias to provide a heat path to the other board layers. TI recommends an unbroken GND plane or GND area of copper on the top and bottom layers.