The Industry's First AC/DC Converter Control IC for SiC Drive

 ROHM has recently 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 easy implementation of SiC-MOSFETs in AC/DC converters. AC/DC converter design has proved challenging when using discrete configurations due to the large number of components required. In contrast, ROHM's latest product provides a highly 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.

Compared to silicon MOSFETs used in conventional AC/DC converters, SiC MOSFETs help improve AC/DC converter efficiency by up to 6%. Furthermore, components used for heat dissipation are not required (in 50W Class power supplies), leading to greater compactness. The BD7682FJ-LB also includes multiple protection functions that enable support for high voltages up to 690VAC, making them ideal for general industrial equipment while improving reliability.

In recent years there has been an increasing trend to conserve energy in all areas, including in high voltage industrial equipment applications. To achieve these targets it is 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 analog 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 MOSFET.

1． 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.

2. SiC MOSFET contributes to unmatched miniaturization
Unlike with conventional Si MOSFETs, adopting SiC MOSFETs (which feature superior performance at high temperatures) 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 and lowering magnetic component costs (such as inductors).

3．Multiple protection circuits support high voltage operation up to 690VAC
Multiple protection circuits enable high voltage operation in AC/DC converters up to 690VAC – ideal for general 400VAC industrial applications. And in addition to overvoltage protection for the supply voltage pin and a brown in/out (undervoltage) countermeasure for the input voltage pin, overcurrent and secondary overvoltage protection functions are included, ensuring continuous operation in industrial equipment while improving reliability considerably.

SiC MOSFET Advantages
SiC MOSFETs provide several advantages over Si MOSFETs in the high voltage region, including lower switching and conduction losses, high power compatibility, and increased resistance to temperature changes. Leveraging these benefits makes it possible to improve power conversion efficiency, miniaturize components for heat dissipation, increase operating frequency to support smaller coils, and more, resulting in increased power savings, lower component count, and smaller mounting area.

Terminology

・SiC (Silicon Carbide)
A compound semiconductor composed of silicon and carbide. Provides characteristics and performance superior to silicon, making it the most viable successor to silicon in the power semiconductor field.

・AC/DC Converter
A type of power supply that converts AC voltage to DC. Generally, devices that operate on DC voltage require additional components to connect to an AC outlet/power source.

・MOSFET (Metal Oxide Semiconductor Field Effect Transistor)
A type of basic semiconductor transistor. External voltage is supplied to turn the transistor ON/OFF. It can also be used as a switching device to control current flow.

・Power Semiconductor
A type of semiconductor that converts voltage and/or current depending on the application, with performance directly linked to the power efficiency of the device and system. Compatibility with large voltages and currents is needed.

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