SLUAAN0 December   2022 TPS62933F

 

  1.   Designing a Simple and Low-Cost Flybuck Solution With the TPS62933F
  2.   Trademarks
  3. 1Introduction
  4. 2Flybuck Converter Device Overview
    1. 2.1 Operation Description
    2. 2.2 Equations for Maximum Output Current
  5. 3Design Flybuck With TPS62933F
    1. 3.1 Primary Voltage and Turns Ratio
    2. 3.2 Feedback Resistor
    3. 3.3 Rectifier Diode
    4. 3.4 Primary Inductance
    5. 3.5 Primary Turns
    6. 3.6 Input and Output Capacitor
    7. 3.7 Pre-Load
    8. 3.8 Factors Affecting Voltage Regulation
    9. 3.9 Avoiding Low-Side Sink Current Limit
  6. 4Experimental Results
  7. 5Conclusion
  8. 6References

3.3 Rectifier Diode

The rectifier diode D1 and D2, must meet the blocking voltage and maximum current requirements (see Equation 14, Equation 15, Equation 16, and Equation 17).

Equation 14. V D 1 = V I N ( m a x ) - V O U T 1 × N 2 N 1 + V O U T 2 = 57.6 V
Equation 15. V D 2 = V I N ( m a x ) - V O U T 1 × N 2 N 1 + V O U T 3 = 57.6 V
Equation 16. i D 1 _ p k = 2 1 - D m a x I O U T 2 = 0.8 A
Equation 17. i D 2 _ p k = 2 1 - D m a x I O U T 3 = 0.8 A

Considering the voltage spike and keeping some margin, as well as the less forward voltage drop, a schottky diode of 70 V or higher reverse voltage rating is required. A 70-V, 2-A diode is selected for each rectifier diode in this design.