ROHM’s New Family of 4-Pin Trench-Gate SiC MOSFETs Aims to Reduce Switching Losses

October 11, 2019 by Gary Elinoff

The SCT3xxx xR series, available in 650V and 1200V VDS versions, can reduce switching losses by up to 35%.

ROHM has announced six devices in the SCT3xxx xR series that will utilize a 4-pin TO-247-4L package instead of conventional 3-pin TO-247N package types. This new family is intended to help increase engineers' efficiency, given its ability to maximize switching performance and lower power consumption.

The TO-247-4L (right) maximizes switch performance to lower power consumption compared to the TO-247N (left). Image by ROHM


Also available is ROHM's SiC MOSFET evaluation board, the P02SCT3040KR-EVK-001, which is equipped with the necessary gate driver, power supply ICs, and relevant discrete components. This board can be used to get products to the market faster.

Trench Gate Structure

The trench gate structure involves forming a groove on the chip surface and the gate on the MOSFET sidewall. This makes it possible to achieve a finer structure compared to planar topologies. The result is an ON resistance close to the original performance of the SiC material, contributing to greater device efficiency.

Why Four Leads?

ROHM highlights the TO-247 package's ability to remove heat—although heat reduction can lead to problems with connections in this type of package, which often come with high series induction.


TO-247N. Image (modified) by ROHM

The voltage drop across this parasitic induction will cut down the signal’s voltage at the chip. That, in turn, will cut down on switching speed. A 4-pin solution, made possible by the TO-247-4L package, effectively separates the driver and power source pins as illustrated below.


TO-247-4L. Image (modified) by ROHM.


This greatly minimizes the impediment that would otherwise be caused by the parasitic inductance component while also maximizing the switching speed of a SiC MOSFET; as a result, the 4-pin packages can dramatically decrease switching power losses.

Members of the SCT3xxx xR Series of SiC MOSFETs

All members of the series are built using a trench gate structure. 


SCT3xxx xR series

Comparison of six models in the SCT3xxx xR series. Image by ROHM


Three devices have a drain-source voltage of 650 volts; the other three feature 1200 volts.

Applications for ROHM’s New Series of SiC MOSFETs

These new devices will be useful anywhere that prioritizes both high power and high efficiency. These include:

  • UPS systems
  • Solar power inverters
  • Power storage systems
  • EV charging stations
  • Power supply for server farms
  • Base stations 

Around the Market

With the increasing demand for power-efficient SiC MOSFETs, it comes as no surprise that the SCT3xxx xR series has several competitors worth considering.

Infineon’s CoolSiC MOSFETs are offered in 4-pin TO-247 packages. RDS(ON) for these 1200-volt devices range from 30 mΩ to 350 mΩ.

Wolfspeed offers its C3M0016120K SiC power MOSFET—also in a 4-lead TO-247 package. The 1200-volt device sports 16 mΩ RDS(ON). The company also lists another seven 4-lead SiC power MOSFETs.
Toshiba’s lineup of four-lead power SiCs includes the TK25Z60X, TK31Z60X, TK39Z60X, and the TK62Z60X. These units feature a breakdown voltage of 600 volts and RDS(ON) values ranging from 40 mΩ to 125 mΩ.



What do you look for in SiC power MOSFETs? Share your thoughts in the comments.