operated from all the typical Si IGBT, Si MOSFET and SiC MOSFET drive voltages and includes a
built-in ESD gate protection clamp.
Along with low on-resistance, these new SiC FETs offer improved efficiency in both hard and soft-
switched circuits. In hard-switched circuits such as Totem-Pole PFC or standard 2-level inverters,
the low on-resistance per unit-area and low output capacitance along with the near-zero stored
charge in the low-voltage Si MOSFET combine to offer superior reverse recovery charge (Q
rr
) and
low E
oss
/Q
oss
. The devices exhibit a superior and robust integral diode with low voltage drop V
F
(<1.75V).
Figure 2 illustrates the advantage of the 750V UnitedSiC FETs versus their 650V rated SiC
competitors when represented as a hard-switching Figure-of-Merit (FoM) of R
DS(on)
x E
oss
. The
UJ4C075018K3S (in TO247-3L package) and UJ4C075018K4S (in TO247-4L package) features a
low on-resistance of 18mohm, which is 50% less at 25
o
C and almost 40% less at 125
o
C compared to
its closest competitor.
Figure 2. Hard-Switching Figure of Merit advantage of UnitedSiC 750V FETs compared to 650V rated SiC competitors
These new devices also offer improved performance in high-frequency, soft-switched resonant
converter topologies such as LLC or PSFB. The breakthrough performance of the 750V UnitedSiC
FETs comes as the on-resistance has been substantially reduced, while at the same time, offering
lower output capacitance, C
oss(tr)
. In Figure 3, the benefit is illustrated with the proposed resonant
or soft-switching FoM, R
DS(on)
x C
oss(tr)
.