“With the continuous popularization of wide band gap technology in traditional and emerging power Electronic applications, semiconductor companies are developing their products at an astonishing speed. In 2021, ON Semiconductor released 650 V silicon carbide (SiC) MOSFET technology to support DC power requirements ranging from hundreds of watts to tens of kilowatts, including automotive traction inverters, electric vehicle (EV) charging, and solar inverters. Applications such as server power supply units (PSU) and uninterruptible power supplies (UPS).
With the continuous popularization of wide band gap technology in traditional and emerging power electronic applications, semiconductor companies are developing their products at an astonishing speed. In 2021, ON Semiconductor released 650 V silicon carbide (SiC) MOSFET technology to support DC power requirements ranging from hundreds of watts to tens of kilowatts, including automotive traction inverters, electric vehicle (EV) charging, and solar inverters. Applications such as server power supply units (PSU) and uninterruptible power supplies (UPS).
SiC MOSFET has proven to be an ideal choice for high-power and high-voltage devices, and its goal is to replace silicon (Si) power switches. SiC MOSFET uses a new technology that provides better switching performance and higher reliability than silicon. In addition, low on-resistance and compact chip size ensure low capacitance and gate charge. Therefore, the system advantages of these devices include higher efficiency, faster operating frequency, higher power density, lower EMI and smaller system size.
ON Semiconductor’s new automotive-grade AECQ101 and industrial-grade 650 V NTH4L015N065SC1 SiC MOSFETs have brought new opportunities. NTH4L015N065SC1 SiC MOSFET’s active cell design combined with advanced thin wafer technology can provide better Rsp (Rdson * area) for devices with a breakdown voltage of 650 V. NTH4L015N065SC1 also has one of the lowest TO247 package Rds(on) on the market. The internal gate resistance (Rg) eliminates the need to use an external gate resistance to artificially reduce the speed of the device, thereby providing engineers with greater design flexibility. Higher robustness against surges, avalanches and short circuits helps to enhance its robustness, thereby providing higher reliability and longer device life. These devices are lead-free and RoHS compliant.
NTH4L015N065SC1 technical parameters
Compared with silicon devices, ON Semiconductor’s SiC MOSFET has a dielectric breakdown field strength 10 times higher, electron saturation speed 2 times higher, energy band gap 3 times higher, and thermal conductivity 3 times higher. The NTH4L015N065SC1 SiC MOSFET device has excellent dynamic and thermal performance, and operates stably at high junction temperatures. In the same range, compared with SiC MOSFET, the competitive characteristics provided by 650V NTH4L015N065SC1 device are as follows:
Lowest on-resistance: typical RDS (on) = 12 m @ VGS = 18 V & typical RDS (on) = 15 m @ VGS = 15 V
Low capacitance and ultra-low gate charge: QG(tot) = 283 nC
High switching speed and low capacitance: Coss = 430 pF
Stable operation at a high junction temperature of 175 degrees Celsius
Excellent avalanche durability with AEC-Q101 certification
Figure 1: NTH4L015N065SC1 SiC MOSFET (picture source: ON Semiconductor)
We are usually used to using three terminals (gate, drain and source) for Si MOSFETs. Figure 1 shows the pin diagram and symbol representation of the NTH4L015N065SC1 SiC MOSFET. A quick glance at the NTH4L015N065SC1 SiC MOSFET data sheet reveals two source terminals: “driver source” and “power source”. The driver source is essentially the reference terminal of the circuit driving the gate, which reduces the negative influence of the inductance in the load current path.
The electrical (static) characterization of SiC MOSFETs includes DC and AC characterization of evaluated performance parameters. The figure below (Figure 2) conveys the current-carrying capacity of the NTH4L015N065SC1 SiC MOSFET in the safe operating area. When the drain-to-source voltage (VDS) is low, the maximum current is limited by the on-state resistance. At medium VDS, the device can withstand hundreds of amperes of current in a short period of time.
Figure 2: NTH4L015N065SC1 SiC MOSFET safe working area (picture source: ON Semiconductor)
SiC MOSFET for automotive
Many power supply circuits and devices can be improved by designing SiC MOSFETs. Automotive electrical systems are one of the biggest beneficiaries of this technology. Modern EV/HEV include equipment using SiC devices. Some popular applications are on-board chargers (OBC), DC-DC converters and traction inverters. Figure 3 points out the main subsystems that require high-power switching transistors in electric vehicles. OBC’s DC-DC converter power circuit converts the high battery voltage into a lower voltage to operate other electrical equipment. The battery voltage is now as high as 600 or 900 volts. A DC-DC converter with SiC MOSFET can reduce this voltage to 48 volts, 12 volts for the operation of other electronic components. The SiC MOSFET in the OBC system allows switching at higher frequencies, improving efficiency and reducing thermal management. The use of new SiC MOSFETs can achieve smaller, lighter, more efficient, and more reliable power solutions.
Figure 3: WBG on-board charger (OBC) for HEV and EV. The AC input is rectified, power factor correction (PFC), and then DC-DC conversion, one of the output is used to charge the high-voltage battery, and the other output is used to charge the low-voltage battery. (Image source: ON Semiconductor)
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