Date: 09/09/2009

Microchip's digital interleaved Power Factor Correction (PFC) reference design

Microchip has announced the digital Interleaved Power Factor Correction (PFC) reference design for green power-supply designs and features of Microchip's dsPIC33 "GS" series of Digital Signal Controllers (DSCs) for Switch Mode Power Supplies (SMPSs). High-performance power supplies are used in a wide variety of applications, including telecommunications and industrial equipment, digital televisions, lighting, air conditioners and other home appliances. Digital interleaved PFC improves the power supply's overall efficiency, along with the input power factor, voltage regulation and the Total Harmonic Distortion (THD) of the input current.

"This reference design enables our customers to quickly bring the benefits of digital interleaved PFC to their products, and create a more efficient and greener power distribution grid," said Sumit Mitra, vice president of Microchip's High Performance Microcontroller Division. "It uses the flexible dsPIC33F "GS" series of DSCs, which enables easy customization and configuration via simple modifications to the control software."

Key features of digital interleaved PFC methods are,

Lower cost for high-power applications
Smaller PFC inductor and magnetic volume
Higher power density
Lower ripple
Easy implementation of sophisticated control algorithms
Flexible software modifications to meet specific customer needs
Simpler integration with other applications

Microchip's Digital Interleaved PFC Reference Design works with a universal input voltage range and produces a single, high-voltage DC output of up to 350W. Its dual-phase interleaved PFC software implements three compensators for voltage, current and load balancing. It also has a feed-forward compensator, based on the average input voltage. This reference design has six main blocks:

Input EMI filter and rectifier
Dual-phase interleaved PFC circuit with feedback
Plug-in module connector, populated with a dsPIC33FJ16GS504 DSC
User-interface circuit with programming connector and push buttons
12V and 3.3V power-supply circuit
Fault-detection circuit for hardware protection

Other key features of Microchip's digital interleaved PFC reference design include:

Operates at universal input voltage (85-265 Vac, 45-65 Hz)
Operates up to 350W sustained output
Output voltages up to 400 Vdc
Power factor correction of 0.998 at full load and 120 VAC input
Current Total Harmonic Distortion (ITHD) of 3% at full load and 120 VAC input

For free documentation, software and reference design is available at www.microchip.com/get/400606844791667