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

3.7 Pre-Load

Pre-load is necessary to prevent VOUT2 and VOUT3 from going too high at light load. The required pre-load current is usually set around 5 mA as a starting point, but it should be adjusted based on the circuit test and application requirements. In this design, the pre-load resistor is selected as 2.2 kΩ for ±12-V outputs. Users can use a Zener diode instead of the pre-load resistor to increase the transfer efficiency.