Recently, unitedsic announced the release of SiC devices with only 6m Ω on resistance (RDS (on)), which responded to the power supply designers’ pursuit of higher performance and higher efficiency SiC FET. At the same time, unitedsic also announced a series of SiC devices with different on resistance, so as to meet the diversified needs of customers. This is also a major update after unitedsic released its first fourth generation SiC FET in 2020.
Liu Luwei, vice president of sales in the Asia Pacific region of unitedsic, and Richard Chen, manager of FAE in the Asia Pacific region, received an exclusive interview with eeworld to interpret the characteristics of the full range of products of the fourth generation SiC FET of unitedsic. The new fourth generation SiC devices support 750V withstand voltage, which can better deal with the extreme conditions of unstable operation of high-voltage bus such as electric vehicles.
New 750V SiC FET series
Unitedsic has released 9 new device / package options with ratings of 6, 9, 11, 23, 33 and 44m Ω. All devices are packaged in to-247-4l, and 18, 23, 33, 44 and 60m Ω devices are also packaged in to-247-3l. This 750V extended series complements the existing 18 and 60m Ω devices. It provides designers with more device solutions and greater design flexibility. Therefore, it can achieve the best cost-effective trade-off while maintaining sufficient design margin and circuit robustness.
Liu Luwei particularly stressed that the unitedsic high-performance FET is based on a unique cascode configuration, in which the high-performance SiC fast JFET is encapsulated with the cascode optimized Si MOSFET, so as to ensure that the gate drive is compatible with typical SiC MOSFET, Si IGBT and Si MOSFET drives. Therefore, the design change is small and can support fast and flexible product substitution. At the same time, the product yield, cost and reliability of this structure are further improved compared with traditional SiC MOSFET.
Richard also stressed that unitedsic’s broader SiC product portfolio can be optimized for customers’ energy consumption, cost or heat dissipation at different power levels, so as to improve design flexibility.
At the same time, in order to cooperate with customer selection, unitedsic also launched FET jet Calculator 2.0. The calculator integrates 26 typical topologies. For engineers who adopt SiC for the first time or are looking for the most suitable design for continuous improvement, this calculator can quickly and simply evaluate the performance of unitedsic FET in various power topologies, so as to avoid wasting time to create advanced simulation for unsuitable devices, so as to speed up research and development.
At the same time, the 6m Ω device also has the industry’s best 5 μ S short-circuit resistance, combined with the short-circuit protection function of the driver, so as to better protect the power devices.
Omnidirectional comparison of the fourth generation SiC FET
Richard interpreted the power consumption advantages of the fourth generation SiC of unitedsic with multiple groups of measured data. Richard said that although the fourth generation SiC is a 750V product, due to the realization of lower RDS (on), according to the actual test results, the conduction loss is greatly reduced compared with 650V products in the industry under the conditions of hard switch and soft switch.
If RDS (on) × According to index a, the 4th generation SiC FET can reach the lowest market value at high and low bare chip temperatures. RDS(on) × EOSs / QoSs, a FOM, is very important in hard switching applications. This value of the 4th generation SiC FET is half that of the closest competitor. RDS(on) × The FOS of coss (TR) is very important in soft switching applications. If the device with rated voltage of 750V of unitedsic is compared with the device with rated voltage of 650V of competitors, the value of the former is about 30% lower than the latter. For hard switching applications, the integrated diode of SiC FET is superior to the competitor’s Si MOSFET or SiC MOSFET technology in recovery speed and forward voltage drop.
Richard said that the third generation SiC products are optimized according to the soft and hard switches, while the excellent performance of the fourth generation products can meet the different needs of soft and hard switches at the same time.
“At present, the actual test results show that the RDS (on) characteristics of the fourth generation SiC of unitedsic are very close to the limit of material characteristics, realizing a real perfect switch,” Richard said.
Wide application space of the fourth generation SiC
With its excellent performance and differentiated combination, the fourth generation SiC can be widely used in fields requiring high performance and efficiency, such as electric vehicles and it infrastructure.
Firstly, in the field of electric vehicles, in order to reduce power loss and weight, the high-voltage bus is constantly improving. Ordinary cars are increasing from 400V to 500V or even higher. 750V SiC has enough design margin to meet the demand of higher voltage.
For the most important traction inverter applications, after the fourth generation SiC is adopted, compared with the efficiency of 750V IGBT system, the loss under full load is only 1 / 3 of the previous one, and in most light load or medium load situations, the loss is only 1 / 5 ~ 1 / 6 of IGBT.
Another mainstream application is for the circuit breaker. The traditional mechanical circuit breaker has a huge volume, complex system, and needs arc removal devices. However, the electronic circuit breaker realized by SiC MOSFET and JFET does not need arc removal circuits, so it can realize the perfect combination of small volume and high efficiency. Similarly, in the concept market such as wireless charging of electric vehicles, the fourth generation products of unitedsic can also achieve better performance.
In addition, for the part of IT infrastructure, because unitedsic products adopt a unique casecode structure, the driver is compatible with the driver of superjunction MOSFET. Customers can directly switch to SiC Based on the existing design to improve efficiency.
According to the actual test results of unitedsic for totem pole PFC and DC / DC LLC, SiC can achieve a very high efficiency level.
According to the actual test results of totem pole PFC, different RDS (on) can be selected according to different load applications, so as to achieve the best efficiency performance.
Compared with superjunction MOSFET, SiC is much better than traditional silicon devices under any load
The fourth generation SiC FET will further reduce the application threshold
Due to the limitation of silicon device characteristics, the progress of traditional MOSFET in improving efficiency is becoming slower and slower, while wide band gap semiconductor is very suitable for electric vehicles, it infrastructure and other applications in pursuit of efficiency because of its characteristics of high frequency, high temperature resistance and high voltage resistance.
With the release of the fourth generation SiC devices of unitedsic, its unique architecture, better RDS (on), higher withstand voltage and robustness, richer product portfolio and better cost performance continuously reduce the threshold of SiC application. At the same time, Liu Luwei also stressed that unitedsic is also actively making capital investment to optimize production capacity to meet customers’ mass production needs.