This is a SMPS Circuit using SG3525 improved over the Application Note in the book SGS Motion Control Application Manual. This worked well. It helps you learn more about High Frequency Power Supply Design.

The PCB and Schematics have been listed below, PCB track thickness and reinforcements are critical. The transformer winding and isolation should be done in a professional manner.

Read about SG2525 - SG3525 - PWM SMPS Regulator Chip.



SG3525Voltage Mode PWM

SG2525 - SG3525 - PWM SMPS Regulator Chip. A second generation ic switch mode controller optimized for high frequency.


Some Notes Related to the Project

• In main circuit do not link different grounds.
• Main circuit can be used both for 110 AC and 230 AC
• Ferrites are partial conductors use proper insulation before winding.
• For main transformer TRX2 use split bobbin for good/safe isolation.
• Epoxy coated toroids have to be further insulated before winding.
• Line of isolation between primary and secondary circuits should be explicit.
• Primary components like Q1, Q2 tabs R5, R6 etc can give shock take caution.
• Each main module is 500W and can be used in parallel for more current.
• Q1 and Q2 should have appropriate isolated heatsinks TO220 type 50sq cm
• Schottky diodes D5, D6 should have heatsinks TO220 type 100sq cm.
• Diodes D5, D6 eg D83004 are TOP3 packages are used 2 in parallel.
• For 200W and above R2=0.1e 5W in the main circuit fusible ceramic.
• C10, C11... Add 4.7uF 100v more in parallel to reduce ripple.
• C13, C14 can be 250V for better safety margin.
• TRX1 SEC1 and SEC2 dot polarity is anti-phase if same phase danger!!

Magnetics Design

All Transformers Isolation 1kV PRI To SEC / SEC To SEC / PRI,SEC To Core. Use Yellow Mylar Tape Insulation or better for all. Vacuum Impregnate all Magnetics in Epoxy or Varnish. All Power Tracks on PCB reinforce with Copper Braid.

TRX1 Mosfet Drive Transformer
T25.0 MGQ-5L Hitachi - Type Torroid - 100khz Signal