TIDT281 June   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
      1. 2.1.1 24-V Output Voltage
      2. 2.1.2 48-V Output Voltage
    2. 2.2 Loss Graphs
      1. 2.2.1 24-V Output Voltage
      2. 2.2.2 48-V Output Voltage
    3. 2.3 Load Regulation
      1. 2.3.1 24-V Output Voltage
      2. 2.3.2 48-V Output Voltage
    4. 2.4 Line Regulation
      1. 2.4.1 24-V Output Voltage
      2. 2.4.2 48-V Output Voltage
    5. 2.5 Thermal Images
    6. 2.6 Bode Plots
      1. 2.6.1 60-V Input Voltage and 24-V Output Voltage
      2. 2.6.2 30-V Input Voltage and 48-V Output Voltage
      3. 2.6.3 Loop Variants
  6. 3Waveforms
    1. 3.1 Switching
      1. 3.1.1 24-V Output Voltage, 30-V Input Voltage (Duty Cycle 80%)
        1. 3.1.1.1 Diode D1
        2. 3.1.1.2 Transistor Q2
          1. 3.1.1.2.1 Drain - GND
          2. 3.1.1.2.2 Gate - GND
        3. 3.1.1.3 Diode D2
        4. 3.1.1.4 Transistor Q1
          1. 3.1.1.4.1 Source - VIN
          2. 3.1.1.4.2 Gate - Source
      2. 3.1.2 24-V Output Voltage; 60-V Input Voltage
        1. 3.1.2.1 Diode D2
        2. 3.1.2.2 Transistor Q1
          1. 3.1.2.2.1 Source - VIN
          2. 3.1.2.2.2 Gate-Source
      3. 3.1.3 48-V Output Voltage; 30-V Input Voltage (Maximum Stress)
        1. 3.1.3.1 Diode D1
        2. 3.1.3.2 Transistor Q2
          1. 3.1.3.2.1 Drain-GND
          2. 3.1.3.2.2 Gate-GND
        3. 3.1.3.3 Diode D2
        4. 3.1.3.4 Transistor Q1
          1. 3.1.3.4.1 Source - VIN
          2. 3.1.3.4.2 Gate - Source
      4. 3.1.4 48-V Output Voltage; 60-V Input Voltage
        1. 3.1.4.1 Diode D1
        2. 3.1.4.2 Transistor Q2
          1. 3.1.4.2.1 Drain - GND
          2. 3.1.4.2.2 Gate - GND
        3. 3.1.4.3 Diode D2
        4. 3.1.4.4 Transistor Q1
          1. 3.1.4.4.1 Source - VIN
          2. 3.1.4.4.2 Gate - Source
    2. 3.2 Output Voltage Ripple
      1. 3.2.1 24-V Output Voltage
      2. 3.2.2 48-V Output Voltage
    3. 3.3 Input Voltage Ripple
      1. 3.3.1 24-V Output Voltage
      2. 3.3.2 48-V Output Voltage
    4. 3.4 Load Transients
      1. 3.4.1 24-V Output Voltage
        1. 3.4.1.1 30-V Input Voltage
        2. 3.4.1.2 60-V Input Voltage
      2. 3.4.2 48-V Output Voltage
        1. 3.4.2.1 30-V Input Voltage
        2. 3.4.2.2 60-V Input Voltage
    5. 3.5 Start-Up Sequence
      1. 3.5.1 24-V Output Voltage
        1. 3.5.1.1 30-V Input Voltage
        2. 3.5.1.2 60-V Input Voltage
      2. 3.5.2 48-V Output Voltage
        1. 3.5.2.1 30-V Input Voltage
        2. 3.5.2.2 60-V Input Voltage
    6. 3.6 Shutdown Sequence
      1. 3.6.1 24-V Output Voltage
        1. 3.6.1.1 30-V Input Voltage
        2. 3.6.1.2 60-V Input Voltage
      2. 3.6.2 48-V Output Voltage
        1. 3.6.2.1 30-V Input Voltage
        2. 3.6.2.2 60-V Input Voltage

Description

This two-switch buck boost controlled by the LM5118 device is stepping up and stepping down an input voltage range of 30 V to 60 V to either 24-V or
48-V output voltage. Jumper #3 at the digital-to-analog converter (DAC) is used to decide for 24 VOUT or 48 VOUT – with jumper 48 VOUT, without 24 VOUT.

For the final application, the 48-V output voltage is just needed for short term use < 1 s. For test purposes the power stage withstands this power level continuously, so the power stage itself could be shrunk for the final application.

Modify the loop bandwidth from between 600 Hz, 1200 Hz, and 2400 Hz – the default is 1.2 kHz. The final application adds a reactive load to the output and needs to be adapted; this prototype supports three different tested variants.