Range and horsepower may get the headlines, but to powertrain designers, drain-source resistance, also known as RDS(on), is a sexy spec. Those in the know are excited over the news that UnitedSiC, a New Jersey-based manufacturer of silicon carbide (SiC) power semiconductors, is introducing four new SiC field-effect transistors (FETs) that boast RDS(on) levels of as low as 7 milliohms.
Of the four new devices, one is rated at 650 V with RDS(on) of 7 mohm and a drain current up to 120 A. The remaining three are rated at 1,200 V, with drain current of 77 A or 120 A, and RDS(on) of 9 or 16 mohm.
The company says these new SiC FETs can deliver higher levels of performance in high-power applications like EV inverters, high-powered DC/DC converters, high-current battery chargers, and solid-state circuit breakers.
The low RDS(on) of these devices makes it possible to achieve efficiencies of more than 99% in inverter designs. The devices can turn off very high currents very quickly. When used as a circuit breaker, they have a self-limiting characteristic that controls the peak current that flows, which designers can use to limit inrush currents flowing into inverters and motors.
These new SiC FETs combine UnitedSiC’s third-generation SiC JFET with a cascode-optimized Si MOSFET. The company says this circuit configuration creates a fast and efficient device that can be driven with the same gate voltages as Si IGBTs, Si MOSFETS and SiC MOSFETs.
“What is really significant here is that we have achieved the industry’s lowest RDS(on) for any device in this class,” said Anup Bhalla, UnitedSiC VP of Engineering. “But in addition to that, the standard drive characteristics and versatile packaging mean these SiC FETs can be used as drop-in replacements for less efficient parts in a wide variety of applications, with little or no additional design effort.”