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

1.2 Considerations

Unless otherwise indicated, all measurements were done with 24-V input voltage and 50-A output current.

The load used was an electronic load TDI RBL100-120-800, limited to 800 WMAX, squeezed up to 828 W; the source was the SMPS Agilent 6574A, limited to a maximum 35-A input current, squeezed up to 35.8 A.

Efficiency and thermal image measurements up to 60-A continuous current are provided, but with a proper thermal interface there is still some headroom left – the current limitation trips at around 70 A.

Unless otherwise indicated, an air flow of 0.5 meters per second (m/s) to 1 m/s was used for the first measurements.


            
CAUTION: Make sure the wiring is properly connected. The output current can
                be as high as 60 A and the input current can be as high as 30 A.

            

                
                GUID-20221026-SS0I-HR0P-KH0P-SQ71MLV7MFJL-low.jpg
            Figure 1-1 Board Image With Connected
                    Cable

            
WARNING:  A 16-mm2
                cable cross section still gets warm and provides a minor voltage drop. Always wear
                eye protection when working with this reference design, and do not wear watches or
                rings.