SNVS690I January   2011  – August 2021 LMZ14201H

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and 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
      1. 7.1.1 COT Control Circuit Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Output Overvoltage Comparator
      2. 7.3.2 Current Limit
      3. 7.3.3 Thermal Protection
      4. 7.3.4 Zero Coil Current Detection
      5. 7.3.5 Prebiased Start-Up
    4. 7.4 Device Functional Modes
      1. 7.4.1 Discontinuous Conduction and Continuous Conduction Modes
  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 Design Steps for the LMZ14201H Application
          1. 8.2.2.1.1 Enable Divider, RENT and RENB Selection
          2. 8.2.2.1.2 Output Voltage Selection
          3. 8.2.2.1.3 Soft-Start Capacitor, CSS, Selection
          4. 8.2.2.1.4 Output Capacitor, CO, Selection
            1. 8.2.2.1.4.1 Capacitance
            2. 8.2.2.1.4.2 ESR
          5. 8.2.2.1.5 Input Capacitor, CIN, Selection
          6. 8.2.2.1.6 ON-Time, RON, Resistor Selection
            1. 8.2.2.1.6.1 Discontinuous Conduction and Continuous Conduction Mode Selection
      3. 8.2.3 Application Curve
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
      1. 10.1.1 Power Module SMT Guidelines
    2. 10.2 Layout Example
      1. 10.2.1 Power Dissipation and Board Thermal Requirements
  11. 11Device and Documentation Support
    1. 11.1 Documentation Support
      1. 11.1.1 Related Documentation
    2. 11.2 Receiving Notification of Documentation Updates
    3. 11.3 Support Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information
8.2.2.1.6.1 Discontinuous Conduction and Continuous Conduction Mode Selection

Operating frequency in DCM can be calculated as follows:

Equation 17. fSW(DCM) ≊ VO × (VIN-1) × 15 μH × 1.18 × 1020 × IO / ((VIN–VO) × RON2)

In CCM, current flows through the inductor through the entire switching cycle and never falls to zero during the OFF-time. The switching frequency remains relatively constant with load current and line voltage variations. The CCM operating frequency can be calculated using Equation 12 above.

The approximate formula for determining the DCM/CCM boundary is as follows:

Equation 18. IDCB ≊ VO × (VIN–VO) / ( 2 × 15 μH × fSW(CCM) × VIN)

The inductor internal to the module is 15 μH. This value was chosen as a good balance between low and high input voltage applications. The main parameter affected by the inductor is the amplitude of the inductor ripple current (ILR). ILR can be calculated with:

Equation 19. ILR P-P = VO × (VIN- VO) / (15 µH × fSW × VIN)

where

  • VIN is the maximum input voltage and fSW is determined from Equation 12.

If the output current IO is determined by assuming that IO = IL, the higher and lower peak of ILR can be determined. Be aware that the lower peak of ILR must be positive if CCM operation is required.