New Industry Products

UnitedSiC Debuts a 750V SiC Power FET with a 6mohm RDS(ON)

September 15, 2021 by Gary Elinoff

The device features a short-circuit withstand time rating of 5μs and is introduced as part of a series of 9 new devices.

The latest members of United SIC’s Gen 4 Series(PR) feature RDS(ON)s of 6, 9, 11, 23, 33, and 44mohms. They join 4 SiC power FETs already in production, as illustrated below. With fully eight RDS(ON)s varying from roughly 6 to 60mΩ, designers will experience a new level of flexibility, and the ability to stay with the same provider over a wide range of use cases.


Image courtesy of UnitedSiC-SlideDeck


The 9 new 750V SiC Power FETS in this series are highlighted in blue. All units, old or new, are available in TO-274-4L packages. The devices with RDS(ON)s of 18, 23, 33, 44 and 58 mohms are also featured with TO-247-3L packages. While no figures for maximum drain currents are apparent for the 9 new series members, the UJCO75018Ks are rated at 81A, and the UJCO75060K are specced at 28A.


Cascode Devices

The Gen 4 SiC FET devices are described in the announcement as “a ‘cascode’ of a SiC JFET and a co-packaged silicon MOSFET.” The arrangement provides the high speed and low losses of SiC technology along with a stable gate drive with integral ESD protection. In an earlier article about the first four Gen 4 devices, we described both cascodes and the fourth “Kelvin” lead.


Figures of Merit

It’s not one size fits all when it comes to figures of merits (FOM), as different combinations of factors take precedence in different design situations. For the new Gen 4 devices, United SiC claims best of class status in

  • RDS(ON) x Area
  • QRR and EON/EOFF losses at a given RDS(ON)
  • COSS(er)/EOSS and COSS(tr), also at a given RDS(ON)

For Hard Switching applications, a low FoM result for RDS(on) x EOSS/QOSS is critical, and UnitedSiC affirms that its result is half that of the nearest competitor.

Complete information is available from The Announcement and at the Slide Deck

As Chris Dries, President and CEO of UnitedSiC describes it. “The UnitedSiC Gen 4 SiC FETs are unquestionably the performance leaders within competing technologies and set a new benchmark in wide bandgap switch technology. The new range additions now provide further options for all performance and budget specifications, and a wider range of applications.”


Backward Compatibility

Gen 4 is not only for new devices, as existing devices can readily be retrofitted, due to Gen 4’s industry-standard TO-247 packaging. Often with few if any engineering changes, established devices can be endowed with an effortless boost in efficiency.


Areas Of Application

United illustrates a range of possibilities in its technical product overview:

  • A 3.6kW Totem-Pole Power Factor Correction (TPPFC) circuit, with peak efficiency of 99.3% is possible. The wide range of RDS(ON)s offered by the SiC FETs comes into play for this design. For maximizing full load efficiency or minimizing the thermal management requirements is of greatest importance, designers may select the UJ4C075018K4S. Light to mid load efficiency would call for another member of the Gen 4 series, with the lowest cost optimized by yet another choice.
  • On-board chargers are design targets, as the FoMs of RDS(ON) x EOSS,  and  RDS(ON) x COSS are both low for Gen 4 devices
  • Traction Inverters
  • Wireless charging
  • Battery charging
  • Power factor Corrections