Microchip announces an AC/DC reference design based on the dsPIC33F “GS” series of digital power Digital Signal Controllers (DSCs). This reference design demonstrates how digital power techniques are applied to reduce component count, lower product cost, eliminate oversized components and incorporate topology flexibility to innovate the best solution for the application.
The unit works with a universal input voltage range and produces three output voltages, with a continuous power output rating of 300Watts. The front-end Power Factor Correction (PFC) boost circuit converts universal AC input voltages to a 420VDC bus voltage. A full bridge transformer isolated buck converter, incorporating a phase-shift Zero Voltage Transition (ZVT) circuit, produces 12VDC @ 30Amps from the 420VDC bus. The phase-shift ZVT converter also provides output-voltage isolation from the AC mains input. A multi-phase synchronous buck converter then produces 3.3VDC @ 69Amps from the 12VDC bus, and a single-phase buck converter produces 5VDC @ 23Amps from the 12VDC bus.
Key design specifications include:
- Universal Inputs (85V - 265V AC, 45 - 65 Hz)
- Boost PFC (PF > 0.98)
- Soft-start (programmable)
- Full-bridge ZVT (soft-switching)
- Synchronous rectification
- 12-Volt intermediate bus
- Multi-phase Synchronous Buck converter 3.3V output
- Single-phase 5.0V output
- Automatic fault handling
- Remote power-management capabilities
- Flexible start-up capabilities
- Greater than 90% efficiency on each of the four power-conversion stages
The reference design is powered by one of Microchip’s new dsPIC33F “GS” series of DSCs, which controls the PFC boost circuit and the primary-side ZVT full-bridge circuit. A second “GS” series dsPIC33F monitors the 12VDC bus voltage and controls the four buck converters. The complete documentation, including software and Gerber files, can be downloaded for free from Microchip’s web site.
