New Industry Products

ROHM Debuts a DC/DC Converter IC with a Built-In 1700-Volt SiC MOSFET

July 02, 2021 by Gary Elinoff

The surface mounted units are housed in TO 263-7L package and deliver up to 48 watts with no heatsink required

The four members of the BM2SC12xFP2-LBZ family of isolated flyback converters allow designers to skip the heatsink and 12 additional parts typically required with designs based on increasingly outdated silicon MOSFETs.

The BM2SC12xFP2-LBZ family. Image courtesy of ROHM

The internal 1700 volt SiC enables the devices to operate over a wide input voltage range. Additionally, the high voltage value is enough to enable the unit to endure any spike that it is liable to run into over the 3-phase input range of 400 to 690 VAC.

The maximum switching speed of 120 kHz allows the device to operate at high efficiency. The devices draw a scant 19 µA during standby. They feature a soft start function and protections for overcurrent, overvoltage, and overtemperature.

The units are designed to serve as converters powering controllers, systems, and sensors requiring from 5- to 48VDC.


New Levels of Miniaturization Made Possible

As claimed by ROHM, the new family of converter ICs makes it possible for designers to eliminate fully 12 components that would be necessary in a design based on silicon semiconductors, most notably the heatsink.

The advantages of members of the BM2SC12xFP2-LBZ family over conventional solutions based on silicon MOSFETs. Image courtesy of ROHM

The high withstand voltage and voltage noise resistance characteristics of the internal 1700 volt SiC MOSFET allows for the use of smaller sized components that must be employed to effect noise suppression. 

Easing the Task of Design

Much of what would be required in the design of a conventional solution are unnecessary with the BM2SC12xFP2 family. As an example, the drive and clamp circuitry are internal to the devices. In addition, fewer components mean greater reliability and a lower BOM.

Greater Power Conversion Efficiency

The new devices feature internal gate driver circuitry to drive the SiC MOSFET. As per ROHM, this maximizes the semiconductor’s performance to a level that improves power conversion efficiency by as much as 5% over what is possible with Si MOSFETs; specifically 84.5% vs 78.5% at 48 watts.

Additionally, the quasi-resonant methodology used by the control circuit not only further increases efficiency, but also enables lower noise output than possible with more conventional pulse width modulated (PWM) systems.


The Four Family Members

VCC overvoltage protection and FB overload protections are: 

  • BM2SC121FP2-LBZ: Latch, Auto Restart
  • BM2SC121FP2-LBZ: Latch, Latch
  • BM2SC121FP2-LBZ: Auto Restart, Auto Restart
  • BM2SC121FP2-LBZ: Auto Restart, Latch


  • Auxiliary power supplies
  • Household appliance
  • Power supplies for industrial equipment
  • AC adaptors

Physical Considerations

  • The four family members are available in 10.18 x 4.43 x 15.5 mm TO263-7L packages. This surface mounted packaging enables automatic machine mounting, simplifying the manufacturing process
  • The devices operate over a temperature range of -40 to +105 °C 


Getting to Market Faster

The BM2SC123FP2-LBZ Reference Board operates over input voltage ranges of 300 to 900 VDC and 210 to 480 VAC. The typical output is 24 VDC at 2 amps for 48 watts.