STMicroelectronics (Geneva, Switzerland) has released a high-efficiency circuit and optimized power components that will produce cost savings and are ideally suited for boost or buck converters - power devices usually used in solar inverters - or SMPS (Switched-Mode Power Supplies) for computers and telecom equipment.
Legislation governing energy efficiency and power quality already requires many types of mains-powered equipment to be fitted with Power Factor Correction (PFC) circuitry to minimize energy loss and distortion. These PFC circuits typically combine a power MOSFET, a rectifier diode, an inductor, and a capacitor. Before, engineers required expensive technology, such as silicon carbide (SiC) for the rectifier diode, to meet high efficiency certification levels.
The new design, called BC2 (Back-Current Circuit), now allows competitively priced silicon diodes to be used in preference to SiC devices. Where the low recovery current of an SiC boost diode helps to minimize the MOSFET switching-on losses, BC2 fully removes these losses and recycles the energy linked to the recovery of the boost diode. Compared to a standard circuit, the new topology requires one additional inductor and three optimized diodes. This approach increases the efficiency by as much as 2% at approximately half the price of a solution using SiC devices.
To enable designers to implement BC2 in new power supply designs, ST has announced a family of six silicon-based rectifiers and free-wheel diodes optimized for this application. Used in kits, these diodes permit the design of competitive high-efficiency circuits up to 2kW.