Component selection and transformer design for viper 22A

[ACP]

Hi everyone,

I’m designing a 3-phase SMPS using the VIPER22A and need some assistance with the transformer design. Below are the key design parameters:

Design Parameters:

• Input Voltage: 150 VAC to 420 VAC (50 Hz)
• Output Voltage: 5.5 V DC, 2 A
• Power Output: 10 W to 11 W
• Frequency: 60 kHz
• Duty Cycle: 50%
• Efficiency: 80%
• VIPER22A: Internal MOSFET requires external StackFET for protection due to high input voltage.

Questions:

1. Transformer Winding Ratio: How do I calculate the winding ratio for primary and secondary windings for this design?
2. Wire Gauge: What wire gauge should I use for the primary, secondary, and auxiliary windings?
3. Inductance: How much inductance is required for each winding?
4. Transformer Core Selection: How do I choose the appropriate core material and size for this design, considering the frequency (60 kHz), power output (10-11 W), and efficiency (80%)?

I’ve attached the schematic for reference.

Thanks in advance for your help!