SNVAA82 august   2023 LMR38020

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2Fly-Buck Converter
  6. 3Fly-Buck Basic Operation
    1. 3.1 Basic Intervals of Steady State Operation
    2. 3.2 Impact Of Leakage Inductor On Fly-Buck Operation
  7. 4Design A Fly-Buck Converter with LMR38020
    1. 4.1 IC Select
    2. 4.2 Switching Frequency Set
    3. 4.3 Transformer Design
      1. 4.3.1 Turns Ratio
      2. 4.3.2 Magnetic Inductance
      3. 4.3.3 Check Ipk
    4. 4.4 Output Capacitor Selection
      1. 4.4.1 Primary Output Capacitor
      2. 4.4.2 Secondary Output Capacitor
    5. 4.5 Secondary Output Diode
    6. 4.6 Preload Resistor
  8. 5Bench Test Results
    1. 5.1 Typical Switching Waveforms Under Steady State
    2. 5.2 Start Up
    3. 5.3 Efficiency
    4. 5.4 Load Regulation
    5. 5.5 Short Circuit
    6. 5.6 Thermal Performance
  9. 6Design Considerations
  10. 7Summary
  11. 8References

4 Design A Fly-Buck Converter with LMR38020

Figure 4-1 shows the schematic for a 12-V output Fly-Buck™ regulator with two 12-V isolated output.

GUID-20230801-SS0I-CCKZ-R2MX-6JZLZ3XHGGW7-low.svgFigure 4-1 Fly-Buck Converter With LMR38020
Table 4-1 Fly-Buck Converter Design Parameters
Design ParameterExample Value
Input voltage range (VIN)16 V to 60 V
Primary output voltage (VOUT1)12.6 V
Primary load current (IOUT1)0.4 A
Isolated output voltage (VOUT2)12 V
Isolated load current (IOUT2)0.1 A
Isolated output voltage (VOUT3)12 V
Isolated load current (IOUT3)0.1 A
Switching frequency (fsw)250 kHz