New Industry Products

AC-DC Converter Control IC Drives SiC FETs

June 25, 2015 by Jeff Shepard

ROHM Semiconductor has announced the development of an ac-dc converter control IC designed specifically for SiC MOSFET drive in industrial equipment such as servers and other large power applications. The BD7682FJ-LB allows the easy implementation of SiC-MOSFETs to an ac-dc converter. ROHM's latest product provide a high integrated solution and creates new standards for energy savings and miniaturization while supporting the adoption of SiC power semiconductors that provide breakthrough levels of efficiency and performance. Samples of this new control IC will be available starting in August.

Compared to silicon MOSFETs used in conventional ac-dc converters, SiC MOSFETs enable ac-dc converters with improved power efficiency by up to 6%. Furthermore, components used for heat dissipation are not required (50W Class power supplies), leading to greater compactness. The specification of BD7682FJ-LB also include multiple protection functions that enable support for high voltages up to 690Vac, making them suited for general industrial equipment while improving reliability.

In recent years there has been an increasing trend to conserve energy in all areas. This includes high voltage industrial equipment applications. To achieve this target it’s necessary to adopt advanced power semiconductors and power supply ICs. Among these, SiC power semiconductors are expected to gain ground over silicon solutions due to their higher voltage capability, greater energy savings, and more compact form factor.

However, until now there has not been a control IC that can sufficiently draw out the performance of SiC MOSFETs, particularly in ac-dc converter systems. As a result designers are faced with numerous problems related to power consumption and stability in a variety of high power applications.

To meet these needs, ROHM utilizes market-proven analogy technology with SiC power semiconductor expertise to develop the industry’s first ac-dc converter controller specialized for driving SiC MOSFETs. And going forward ROHM will continue to pioneer industry-leading solutions, including the development of new ac-dc converter control ICs with integrated SiC MOSFETs.

Key features include: Maximizes SiC MOSFET performance for breakthrough energy savings The BD7682FJ-LB integrates a gate drive circuit optimized for SiC MOSFET drive by combining analog design technology with SiC power semiconductor development expertise. In addition, a quasi-resonant system delivers lower noise and higher efficiency vs conventional pwm methods, making it possible to maximize the performance of SiC MOSFETs used in ac-dc converters, resulting in significant power savings.

SiC MOSFET contributes to unmatched miniaturization Unlike with conventional Si MOSFETs, adopting SiC MOSFETs in ac-dc converters eliminates the need for components used for heat dissipation, contributing to smaller, lighter ac-dc converter designs. Support for higher switching frequencies (i.e. 120kHz) is also ensured, expanding applicability while improving efficiency.

Multiple protection circuits support high voltage operation up to 690Vac Various protection circuits enable high voltage operation in ac-dc converters up to 690Vac – well-suited for general 400Vac industrial applications. And in addition to overvoltage protection for the supply voltage pin and brown in/out (undervoltage) countermeasure for the input voltage pin, overcurrent and secondary overvoltage protection functions are included, enabling continuous operation in industrial equipment while improving reliability considerably.