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

3.2 Feedback Resistor

With the expected primary voltage set point at 5 V, and VFB = 0.8 V (typical), VOUT1 is calculated to be as in Equation 12:

Equation 12. Vout1=VFB×1+R7R8

Start with 10 kΩ for the lower resistor divider, R8 = 10.2 kΩ (see Equation 13).

Equation 13. R 7 = V o u t 1 - V F B V F B R 8

Next choose R7 = 53.6 kΩ. The 49.9-Ω resistor, R5, is provided as a convenient location to break the control loop for stability testing.