Silicon Carbide MOSFETs for High Power and High Voltage Devices

15 Apr 2021

Related Blogs: Power Management

As wide-bandgap technologies continue to populate traditional and emerging power electronics applications, semiconductor companies are developing their product offerings at a blistering pace. In 2021, ON Semiconductor released 650 V Silicon Carbide (SiC) MOSFET technology to support the need for DC power supplies ranging from several hundred watts to tens of kilowatts, which includes applications like automotive traction inverters, Electric Vehicle (EV) charging, solar inverters, server power supply units (PSUs), and uninterruptible power supplies (UPSs).

SiC MOSFETs have proven to be ideal for high power and high voltage devices, and are targeted as a replacement for Silicon (Si) power switches. SiC MOSFETs use an entirely new technology that provides superior switching performance and higher reliability than Silicon. In addition, the low ON resistance and compact chip size ensure low capacitance and gate charge. Consequently, system benefits from these devices include higher efficiency, faster operation frequency, increased power density, reduced EMI, and reduced system size.

ON Semiconductor's new automotive AECQ101 and industrial-grade qualified 650 V NTH4L015N065SC1 SiC MOSFETs create a new opportunity for the under-serviced power band. The active cell design of the NTH4L015N065SC1 SiC MOSFET, combined with advanced thin wafer technology, enable a high performance in Rsp (Rdson*area) for a device with a 650 V breakdown voltage. The NTH4L015N065SC1 also has one of the lowest Rds(on)s in the market for TO247 packages. An internal gate resistor (Rg) gives engineers greater design flexibility by eliminating the need to artificially slow down devices using external gate resistors. Higher surge, avalanche capability, and short-circuit robustness contribute to its enhanced ruggedness, which delivers higher reliability and longer device lifetimes. These devices are Pb−Free and are RoHS Compliant.

NTH4L015N065SC1 Technology Parameters

As compared to Silicon devices, SiC MOSFETs from ON Semiconductor have 10x higher dielectric breakdown field strength, 2x higher electron saturation velocity, 3x higher energy bandgap, and 3x higher thermal conductivity. The NTH4L015N065SC1 SiC MOSFET device offers superior dynamic and thermal performance with stable operation at high junction temperatures. The competitive features offered by the 650V NTH4L015N065SC1 device compared to SiC MOSFET in the same range are as follows:

Lowest ON resistance: Typical RDS (on) = 12 m @ VGS = 18 V & Typical RDS(on) = 15 m @ VGS = 15 V
Low capacitances and ultra-low gate charge: QG(tot) = 283 nC
High switching speed with Low Capacitance: Coss = 430 pF
Stable operation at high junction temperatures of 175 degrees Celsius
Superior avalanche ruggedness with AEC-Q101 qualification

Case	Pinout Diagram

Figure 1: NTH4L015N065SC1 SiC MOSFET (Image Source: ON Semiconductor) Buy Now

We are typically accustomed to three-terminals--gate, drain, and source—for a Si MOSFET. Figure 1 represents the pin diagram and symbolic representation of the NTH4L015N065SC1 SiC MOSFET. A quick look at the datasheet for the NTH4L015N065SC1 SiC MOSFET reveals two source terminals: "driver source" and "power source." The driver source is essentially a reference terminal for the circuitry driving the gate, and it reduces the negative effect of the inductance in the load-current path.

Electric (static) characterizations of SiC MOSFETs include DC and AC characterization with evaluated performance parameters. The following plot (Figure 2) conveys the current-carrying abilities of the NTH4L015N065SC1 SiC MOSFET for a safe operating area. When the drain-to-source voltage (VDS) is low, the maximum current is limited by the on-state resistance. At moderate VDS, the device can sustain hundreds of amperes for short periods.

Figure 2: NTH4L015N065SC1 SiC MOSFET Safe Operating Area (Image Source: ON Semiconductor)

SiC MOSFETs for Automotive Applications

Many power circuits and devices can be improved by designing with SiC MOSFETs. One of the biggest beneficiaries of this technology is automotive electrical systems. A modern EV/HEV contains equipment that uses SiC devices. Some of the popular applications are onboard chargers (OBCs), DC−DC converters, and Traction Inverters. Figure 3 notes the main subsystems in an EV that require high power switching transistors. The DC−DC converter power circuit of the OBC converts the high battery voltage down to a lower voltage to operate other electrical equipment. Battery voltages now range up to 600 or 900 volts. A DC−DC converter with SiC MOSFETs drops this down to 48 volts, 12 volts, or both for the operation of other electronic components. SiC MOSFETs in the OBC systems allow switching at higher frequencies, enhance efficiencies, and reduce thermal management. Using the new SiC MOSFETs results in a smaller, lighter, more efficient, and more reliable power solution.

Figure 3: A WBG On−board Charger (OBC) for HEVs and EVs. The AC input is rectified, power factor corrected (PFC), and then DC−DC converted, with one output for charging the HV battery and the other for charging the LV battery. (Image Source: ON Semiconductor)

Giveaway: Register here to win ON Semiconductor’s NCP51705SMDGEVB silicon carbide evaluation board designed on a four-layer printed circuit board which includes the NCP51705 driver and all the necessary drive circuitry.

For more information: about On Semiconductor's power management products, click here for more information.

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