TIDT315 December   2022

 

  1.   Description
  2.   Features
  3.   Applications
  4. 1Test Prerequisites
    1. 1.1 Voltage and Current Requirements
    2. 1.2 Considerations
    3. 1.3 Dimensions
  5. 2Testing and Results
    1. 2.1 Efficiency Graphs
    2. 2.2 Load Regulation
    3. 2.3 Thermal Images
      1. 2.3.1 Summary
      2. 2.3.2 Images With Thermal Interface Aluminum Adapter, Then Added Heat Sink to Adapter
      3. 2.3.3 Images Without Thermal Mechanics
      4. 2.3.4 Thermal Mechanics
        1. 2.3.4.1 Summary
        2. 2.3.4.2 Description – Mechanical Setup Needs a Workshop
    4. 2.4 Bode Plot
      1. 2.4.1 Bode Plot Using Quick Start Design Tool
      2. 2.4.2 Bode Plot Using Network Analyzer
  6. 3Waveforms
    1. 3.1 Switching
      1. 3.1.1 Overview of the Four Switching Phases
      2. 3.1.2 Low-Side FET
        1. 3.1.2.1 Switch Node to GND
        2. 3.1.2.2 Low-Side FET Gate to GND
      3. 3.1.3 High-Side FET
        1. 3.1.3.1 Switch Node to VIN
        2. 3.1.3.2 High-Side FET Gate to Switch Node
    2. 3.2 Output Voltage Ripple
    3. 3.3 Input Voltage Ripple
      1. 3.3.1 Power Stage Input
      2. 3.3.2 Board Input
    4. 3.4 Load Transients
      1. 3.4.1 Load Transient 10 A to 50 A
      2. 3.4.2 Load Transient 5 A to 50 A (90 %)
    5. 3.5 Start-Up Sequence
    6. 3.6 Shutdown Sequence
  7.   A Individual Adjusting of the Rising Edge and Falling Edge With LM5143A
    1.     A.1 Both Gate Resistors Before Gate Shorted
    2.     A.2 2 × 3.32-Ω Resistors in Before Gate of the High-Side FET
    3.     A.3 2.21-Ω High and 4.75-Ω Low Resistor in Before Gate of the High-Side FET
  8.   B Thermal Behavior, Prototype in Vertical Position
    1.     B.1 Thermal Summary
    2.     B.2 Thermal Images PCB with Heat Sink and Prototype in the Vertical Position
  9.   C ON Demand – Assembly of Thermal Interface
    1.     C.1 Thermal Interface Example

Description

This reference design is a 700-W buck converter using the LM5143A-Q1 device. Due to lowest dead times, ultra-strong drivers, and the ability to adjust the rising edge and falling edge individually, the resulting efficiency is 98%.

Due to the reduced loss, the board area is also greatly reduced, now 150 mm × 125 mm, with a low profile of 12 mm or 15 mm, depending on the inductor selected.

Ample headroom for increased output power is available by using forced cooling or a heat sink mounted to a chassis. Using additional cooling options, the output current can be increased to 60-A continuous and higher.

The interleaved operation results in low RMS (root mean square) stress at the input capacitor and reduced ripple at the input and the output. A generic two stage EMI input filter is provided.