SNVSC09 March   2022 LM5143

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Description (continued)
  6. 6 Device Comparison Table
  7. 7 Pin Configuration and Functions
  8. 8 Specifications
    1. 8.1 Absolute Maximum Ratings
    2. 8.2 ESD Ratings
    3. 8.3 Recommended Operating Conditions
    4. 8.4 Thermal Information
    5. 8.5 Electrical Characteristics
    6. 8.6 Switching Characteristics
    7. 8.7 Typical Characteristics
  9. 9 Detailed Description
    1. 9.1 Overview
    2. 9.2 Functional Block Diagram
    3. 9.3 Feature Description
      1. 9.3.1  Input Voltage Range (VIN)
      2. 9.3.2  High-Voltage Bias Supply Regulator (VCC, VCCX, VDDA)
      3. 9.3.3  Enable (EN1, EN2)
      4. 9.3.4  Power-Good Monitor (PG1, PG2)
      5. 9.3.5  Switching Frequency (RT)
      6. 9.3.6  Clock Synchronization (DEMB)
      7. 9.3.7  Synchronization Out (SYNCOUT)
      8. 9.3.8  Spread Spectrum Frequency Modulation (DITH)
      9. 9.3.9  Configurable Soft Start (SS1, SS2)
      10. 9.3.10 Output Voltage Setpoint (FB1, FB2)
      11. 9.3.11 Minimum Controllable On Time
      12. 9.3.12 Error Amplifier and PWM Comparator (FB1, FB2, COMP1, COMP2)
      13. 9.3.13 Slope Compensation
      14. 9.3.14 Inductor Current Sense (CS1, VOUT1, CS2, VOUT2)
        1. 9.3.14.1 Shunt Current Sensing
        2. 9.3.14.2 Inductor DCR Current Sensing
      15. 9.3.15 Hiccup Mode Current Limiting (RES)
      16. 9.3.16 High-Side and Low-Side Gate Drivers (HO1/2, LO1/2, HOL1/2, LOL1/2)
      17. 9.3.17 Output Configurations (MODE, FB2)
        1. 9.3.17.1 Independent Dual-Output Operation
        2. 9.3.17.2 Single-Output Interleaved Operation
        3. 9.3.17.3 Single-Output Multiphase Operation
    4. 9.4 Device Functional Modes
      1. 9.4.1 Standby Modes
      2. 9.4.2 Diode Emulation Mode
      3. 9.4.3 Thermal Shutdown
  10. 10Application and Implementation
    1. 10.1 Application Information
      1. 10.1.1 Power Train Components
        1. 10.1.1.1 Buck Inductor
        2. 10.1.1.2 Output Capacitors
        3. 10.1.1.3 Input Capacitors
        4. 10.1.1.4 Power MOSFETs
        5. 10.1.1.5 EMI Filter
      2. 10.1.2 Error Amplifier and Compensation
    2. 10.2 Typical Applications
      1. 10.2.1 Design 1 – 5-V and 3.3-V Dual-Output Buck Regulator for Computing Applications
        1. 10.2.1.1 Design Requirements
        2. 10.2.1.2 Detailed Design Procedure
          1. 10.2.1.2.1 Custom Design With WEBENCH® Tools
          2. 10.2.1.2.2 Custom Design With Excel Quickstart Tool
          3. 10.2.1.2.3 Inductor Calculation
          4. 10.2.1.2.4 Current-Sense Resistance
          5. 10.2.1.2.5 Output Capacitors
          6. 10.2.1.2.6 Input Capacitors
          7. 10.2.1.2.7 Compensation Components
        3. 10.2.1.3 Application Curves
      2. 10.2.2 Design 2 – Two-Phase, 15-A, 2.1-MHz Single-Output Buck Regulator for Server Applications
        1. 10.2.2.1 Design Requirements
        2. 10.2.2.2 Detailed Design Procedure
        3. 10.2.2.3 Application Curves
      3. 10.2.3 Design 3 – Two-Phase, 50-A, 300-kHz Single-Output Buck Regulator for ASIC Power Applications
        1. 10.2.3.1 Design Requirements
        2. 10.2.3.2 Detailed Design Procedure
        3. 10.2.3.3 Application Curves
  11. 11Power Supply Recommendations
  12. 12Layout
    1. 12.1 Layout Guidelines
      1. 12.1.1 Power Stage Layout
      2. 12.1.2 Gate-Drive Layout
      3. 12.1.3 PWM Controller Layout
      4. 12.1.4 Thermal Design and Layout
      5. 12.1.5 Ground Plane Design
    2. 12.2 Layout Example
  13. 13Device and Documentation Support
    1. 13.1 Device Support
      1. 13.1.1 Third-Party Products Disclaimer
      2. 13.1.2 Development Support
        1. 13.1.2.1 Custom Design With WEBENCH® Tools
    2. 13.2 Documentation Support
      1. 13.2.1 Related Documentation
        1. 13.2.1.1 PCB Layout Resources
        2. 13.2.1.2 Thermal Design Resources
    3. 13.3 Receiving Notification of Documentation Updates
    4. 13.4 Support Resources
    5. 13.5 Trademarks
    6. 13.6 Electrostatic Discharge Caution
    7. 13.7 Glossary
  14. 14Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

10.2.1.1 Design Requirements

Table 10-2 shows the intended input, output, and performance parameters for this design example.

Table 10-2 Design Parameters
Design Parameter Value
Input voltage range (steady state) 8 V to 18 V
Min transient input voltage (cold crank) 3.5 V
Max transient input voltage (load dump) 36 V
Output voltages 3.3 V, 5 V
Output currents 7 A
Switching frequency 2.1 MHz
Output voltage regulation ±1%
Standby current, output 1 enabled, no load < 50 µA
Shutdown current 4 µA

The switching frequency is set at 2.1 MHz by resistor RRT. In terms of control loop performance, the target loop crossover frequency is 60 kHz with a phase margin greater than 50°. The output voltage soft-start times are set at 2 ms by 68-nF soft-start capacitors.

The selected buck regulator powertrain components are cited in Table 10-3, and many of the components are available from multiple vendors. The MOSFETs in particular are chosen for both lowest conduction and switching power loss, as discussed in detail in Section 10.1.1.4. This design uses a low-DCR, metal-powder composite inductor, and ceramic output capacitor implementation.

Table 10-3 List of Materials for Application Circuit 1
Ref Des Qty Specification Manufacturer(1) Part Number
CIN 4 10 µF, 50 V, X7R, 1210, ceramic Taiyo Yuden UMJ325KB7106KMHT
10 µF, 50 V, X7S, 1210, ceramic Murata GCM32EC71H106KA03
TDK CGA6P3X7S1H106M
CO 8 47 µF, 6.3 V, X7R, 1210, ceramic Murata GCM32ER70J476KE19L
Taiyo Yuden JMK325B7476KMHTR
47 µF, 6.3 V, X7S, 1210, ceramic TDK CGA6P1X7S0J476M
LO1, LO2 2 0.68 µH, 4.8 mΩ, 25 A, 7.3 × 6.6 × 2.8 mm Würth Elektronik 744373460068
0.68 µH, 4.5 mΩ, 22 A, 6.95 × 6.6 × 2.8 mm Cyntec VCMV063T-R68MN2T
0.68 µH, 3.1 mΩ, 20 A, 7 × 6.9 × 3.8 mm Würth Elektronik 744311068
0.68 µH, 7.4 mΩ, 12.2 A, 5.4 × 5.0 × 3 mm TDK SPM5030VT-R68-D
0.68 µH, 2.9 mΩ, 15.3 A, 6.7 × 6.5 × 3.1 mm Coilcraft XGL6030-681
Q1, Q2, Q3, Q4 4 40 V, 5.7 mΩ, 9 nC, SON 5 × 6 Infineon IPC50N04S5L-5R5
RS1, RS2 2 Shunt, 7 mΩ, 0508, 1 W Susumu KRL2012E-M-R007
U1 1 LM5143 65-V dual-channel/phase synchronous buck controller Texas Instruments LM5143RHAR