TIDT271 April   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 Line Regulation
    4. 2.4 Thermal Images
      1. 2.4.1 18-V Input Voltage and 500-mA Output Current
      2. 2.4.2 24-V Input Voltage and 500-mA Output Current
      3. 2.4.3 36-V Input Voltage and 500-mA Output Current
    5. 2.5 Bode Plots
      1. 2.5.1 18-V Input Voltage
      2. 2.5.2 24-V Input Voltage
      3. 2.5.3 32-V Input Voltage
  6. 3Waveforms
    1. 3.1 Switching
      1. 3.1.1 Transistor Q1 Drain-GND
        1. 3.1.1.1 18-V Input Voltage
        2. 3.1.1.2 24-V Input Voltage
      2. 3.1.2 Transistor Q1 Gate-Source
        1. 3.1.2.1 18-V Input Voltage
        2. 3.1.2.2 24-V Input Voltage
    2. 3.2 Output Voltage Ripple
      1. 3.2.1 18-V Input Voltage
      2. 3.2.2 24-V Input Voltage
    3. 3.3 Input Voltage Ripple
      1. 3.3.1 18-V Input Voltage
        1. 3.3.1.1 Input Terminal J2
        2. 3.3.1.2 Power Stage Input
      2. 3.3.2 24-V Input Voltage
        1. 3.3.2.1 Input Terminal J2
        2. 3.3.2.2 Power Stage Input
    4. 3.4 Load Transients
      1. 3.4.1 18-V Input Voltage
      2. 3.4.2 24-V Input Voltage
    5. 3.5 Start-Up Sequence
      1. 3.5.1 18-V Input Voltage
      2. 3.5.2 24-V Input Voltage
    6. 3.6 Shutdown Sequence
      1. 3.6.1 18-V Input Voltage
      2. 3.6.2 24-V Input Voltage

1.2 Considerations

Unless otherwise indicated, the resistor was used as load. The output current was adjusted to 0.5 A.

The circuit switches on at 20.8 V and off at 17.9 V. This individual circuit switches around 130 kHz (128 kHz on the reference board).

The converter itself works in DCM mode. This reference design has been optimized for low size, therefore a transformer with a small footprint was used. This small footprint results in higher heating in the inductor core. The higher temperatures can be reduced with a larger size transformer, for example, MSD-1578-223.