SNVSB29C October   2018  – June 2021 LM5143-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
    1. 6.1 Wettable Flanks
  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 Switching 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  Input Voltage Range (VIN)
      2. 8.3.2  High-Voltage Bias Supply Regulator (VCC, VCCX, VDDA)
      3. 8.3.3  Enable (EN1, EN2)
      4. 8.3.4  Power Good Monitor (PG1, PG2)
      5. 8.3.5  Switching Frequency (RT)
      6. 8.3.6  Clock Synchronization (DEMB)
      7. 8.3.7  Synchronization Out (SYNCOUT)
      8. 8.3.8  Spread Spectrum Frequency Modulation (DITH)
      9. 8.3.9  Configurable Soft Start (SS1, SS2)
      10. 8.3.10 Output Voltage Setpoint (FB1, FB2)
      11. 8.3.11 Minimum Controllable On-Time
      12. 8.3.12 Error Amplifier and PWM Comparator (FB1, FB2, COMP1, COMP2)
      13. 8.3.13 Slope Compensation
      14. 8.3.14 Inductor Current Sense (CS1, VOUT1, CS2, VOUT2)
        1. 8.3.14.1 Shunt Current Sensing
        2. 8.3.14.2 Inductor DCR Current Sensing
      15. 8.3.15 Hiccup Mode Current Limiting (RES)
      16. 8.3.16 High-Side and Low-Side Gate Drivers (HO1/2, LO1/2, HOL1/2, LOL1/2)
      17. 8.3.17 Output Configurations (MODE, FB2)
        1. 8.3.17.1 Independent Dual-Output Operation
        2. 8.3.17.2 Single-Output Interleaved Operation
        3. 8.3.17.3 Single-Output Multiphase Operation
    4. 8.4 Device Functional Modes
      1. 8.4.1 Standby Modes
      2. 8.4.2 Diode Emulation Mode
      3. 8.4.3 Thermal Shutdown
  9. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Power Train Components
        1. 9.1.1.1 Buck Inductor
        2. 9.1.1.2 Output Capacitors
        3. 9.1.1.3 Input Capacitors
        4. 9.1.1.4 Power MOSFETs
        5. 9.1.1.5 EMI Filter
      2. 9.1.2 Error Amplifier and Compensation
    2. 9.2 Typical Applications
      1. 9.2.1 Design 1 – High Efficiency, Dual-Output Buck Regulator for Automotive Applications
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
          1. 9.2.1.2.1 Custom Design With WEBENCH® Tools
          2. 9.2.1.2.2 Custom Design With Excel Quickstart Tool
          3. 9.2.1.2.3 Inductor Calculation
          4. 9.2.1.2.4 Current-Sense Resistance
          5. 9.2.1.2.5 Output Capacitors
          6. 9.2.1.2.6 Input Capacitors
          7. 9.2.1.2.7 Compensation Components
        3. 9.2.1.3 Application Curves
      2. 9.2.2 Design 2 – Two-Phase, Single-Output Buck Regulator for Automotive ADAS Applications
        1. 9.2.2.1 Design Requirements
        2. 9.2.2.2 Detailed Design Procedures
        3. 9.2.2.3 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
      1. 11.1.1 Power Stage Layout
      2. 11.1.2 Gate-Drive Layout
      3. 11.1.3 PWM Controller Layout
      4. 11.1.4 Thermal Design and Layout
      5. 11.1.5 Ground Plane Design
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Device Support
      1. 12.1.1 Third-Party Products Disclaimer
      2. 12.1.2 Development Support
      3. 12.1.3 Custom Design With WEBENCH® Tools
    2. 12.2 Documentation Support
      1. 12.2.1 Related Documentation
        1. 12.2.1.1 PCB Layout Resources
        2. 12.2.1.2 Thermal Design Resources
    3. 12.3 Receiving Notification of Documentation Updates
    4. 12.4 Support Resources
    5. 12.5 Trademarks
    6. 12.6 Electrostatic Discharge Caution
    7. 12.7 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information
9.2.1.2.4 Current-Sense Resistance
  1. Calculate the current-sense resistance based on a maximum peak current capability of at least 20% higher than the peak inductor current at full load to provide sufficient margin during start-up and load-on transients. Calculate the current sense resistances using Equation 36.
    Equation 36. GUID-0210DFAA-85DE-45E5-B95A-C2FAF2981D75-low.gif

    where

    • VCS(th) is the 73-mV current limit threshold.
  2. Select a standard resistance value of 7 mΩ for both shunts. A 0508 footprint component with wide aspect ratio termination design provides 1-W power rating, low parasitic series inductance, and compact PCB layout. Carefully observe the Section 11.1 to make sure that noise and DC errors do not corrupt the differential current-sense voltages measured at [CS1, VOUT1] and [CS2, VOUT2].
  3. Place the shunt resistor close to the inductor.
  4. Use Kelvin-sense connections, and route the sense lines differentially from the shunt to the LM5143-Q1.
  5. The CS-to-output propagation delay (related to the current limit comparator, internal logic and power MOSFET gate drivers) causes the peak current to increase above the calculated current limit threshold. For a total propagation delay of tCS-DELAY of 40 ns, use Equation 37 to calculate the worst-case peak inductor current with the output shorted.
    Equation 37. GUID-64B88A33-D0EB-463C-A620-1BCFA3A6DF87-low.gif
  6. Based on this result, select an inductor for each channel with saturation current greater than 12 A across the full operating temperature range.