An auxiliary power supply is an essential and vital part of industrial applications, providing different DC voltage levels for gate drivers and control units. When using existing silicon MOSFET devices, the designer cannot achieve higher efficiency or higher power output due to the higher losses inherent in silicon devices. Existing solutions require a heatsink and additional components, which increase both device losses and system size due to the extra space required. Designing an auxiliary power supply with existing silicon devices is also expensive due to a longer bill of materials (BOM).
ROHM's BM2SC12xFP2-LBZ power ICs are quasi-resonant (QR) AC/DC converters with a built-in 1700V SiC MOSFET in a single compact surface-mount (TO263) package. These ICs are the most suitable and best-in-class products for industrial auxiliary power supply solutions in terms of efficiency, as they shorten design time, simplify circuitry, and reduce the number of additional components by offering integrated solutions. These ICs also increase product reliability by minimizing the risk of component failure.
When used in 400 VAC, 48 W output auxiliary power supplies, in addition to enabling automated board mounting that was previously impossible, the number of external parts can also be significantly reduced compared to standard configurations: from 12 parts and a heatsink to just one.
(Fig. 2)
At the same time, adopting a SiC MOSFET improves energy efficiency by up to 5% and minimizes the risk of component failure. This dramatically increases reliability and energy savings in industrial equipment, while also significantly reducing assembly area and costs.
In addition, designers can also use ROHM's BM2SC123FP2-EVK-001 evaluation board, which utilizes our BM2SC123FP2-LBZ AC/DC integrated circuit. This board delivers up to 48 W at 400 VAC without requiring a heatsink. Test results on the evaluation board show that the output voltage (24 V) is constant and independent of the input voltage.
(Fig. 3)
ROHM is committed to further developing advanced control ICs and power semiconductors, such as SiC devices, while providing optimized solutions that contribute to greater energy savings and performance in industrial equipment.
Range of AC/DC converter ICs with built-in SiC MOSFET (table) 
Application examples
- General purpose inverters
- AC servos
- PLCs (programmable logic controllers)
- Manufacturing equipment
- Robots
- Commercial air conditioning systems
- Industrial lighting (e.g., streetlights)
Optimized for auxiliary power supply circuits that handle indicators, fans, relays and PLCs in 400 VAC industrial equipment.
