Wolfspeed provides an isolated gate driver to protect control circuits from high voltages encountered during power conversion designs. Additionally, this design comes complete with a BOM to facilitate use of Broadcom optocouplers for reinforced galvanic isolation.
Efficiency tests conducted against first-generation SiC MOSFETs versus silicon IGBTs demonstrate that the new device can increase overall system efficiency by as much as two percent by operating at switching frequencies three times faster than those employed with conventional silicon devices.
Size
Silicon carbide MOSFETs represent an exciting development in power semiconductor technology. Operating at higher voltages and temperatures than their silicon counterparts, Sic MOSFETs help reduce power losses when power conversion circuits use energy efficient power conversion methods, revolutionizing industries while offering sustainable alternatives to conventional devices.
Cree introduced its CMF20120D SiC power transistor, the world’s first of its kind. Rated at 1200V and featuring 80mO on-resistance, this device served as an ideal replacement for Si IGBTs despite incurring higher costs due to faster switching and increased efficiency. Although more expensive, its superior performance more than justified these additional expenses.
At present, numerous vendors produce SiC power semiconductors, such as CREE/Wolfspeed, Microsemi, Infineon, GeneSiC and ST. Each offers various voltage and current ratings along with packaging options that can withstand temperatures as high as 210 degC.
These chips feature a planar or trench design with a pMOSFET gate-oxide structure and low RDS(on) at high temperatures compared to standard MOSFETs, enabling designers to increase switching frequencies for optimal power conversion designs; their efficiency may even surpass that of existing silicon MOSFETs by threefold!
Weight
Cree’s silicon carbide power MOSFET was designed to meet all the demands for high voltage switching devices, offering increased efficiency at cost parity with leading silicon IGBT devices. It features an incredible 650V blocking voltage which enables designers to meet or surpass even the strictest power density and efficiency requirements, such as those set forth by 80 Plus Titanium requirements for server power, while offering up to 70% greater density than current silicon-based solutions.
Comparative to silicon IGBTs, the CMF20120D device can decrease switching losses by as much as 50% and increase system efficiency 2-3 times when operated at twice their switching frequency. Furthermore, its ultra-low body diode reverse recovery charge enables smaller parasitics which help decrease operating temperatures and operating temperatures.
The C2M0025120D device is compatible with standard gate driver circuits and can be combined with SiC Schottky diodes from the company to create complete power module solutions. With its pulsed current rating and positive temperature coefficient, this device makes an ideal addition for medical imaging applications like CT systems requiring reduced switching loss (allowing fans to be removed without replacing).
This device comes in a D2Pak-7L surface mount package and boasts low on-resistance (QG less than 100nC) across its recommended input voltage range, along with the lowest gate drive energy of any 1200V SiC MOSFET available today. Furthermore, this MOSFET also boasts a rated voltage drop across its recommended current range with forward drop being less than 2V at 20A current levels.
Efficiency
SiC MOSFETs and IGBTs exhibit significantly greater efficiency compared to traditional silicon MOSFETs and IGBTs, due to lower switching losses as well as less dependence on voltage/frequency dependency than their silicon counterparts. This results in greater conversion efficiencies with reduced total cost of ownership in power electronics applications.
The 1200V SiC MoSfet is an ideal replacement for silicon IGBTs in 3-10kW PV inverters and other high-voltage DC power supplies, such as UPS systems and industrial motor drives. Furthermore, this device enables significant size and weight reductions as well as twice the maximum torque than similarly rated silicon power semiconductors.
The 1200V SiC MOSFET comes in both TO-247 packaged dies and plastic packages, each designed for optimal system cost and performance. Packaged devices have a 1200V blocking voltage with 80mO on-resistance while dies have 25 mOhm resistance ratings to serve as 50 amp building blocks in high-power modules. Multiple devices may be connected in parallel for optimal system cost and performance.
Reliability
Quality service from your manufacturer is critical to the success of your design project. In addition to qualification testing, it’s crucial that device hours and life prediction models for power devices be considered; these tools help predict mean time to failure (MTTF) rates of silicon power semiconductors.
Studies were conducted to analyze the short-circuit reliability of 1200 V SiC metal-oxide-semiconductor field-effect transistors (MOSFETs) manufactured by different manufacturers and found they can withstand high surge currents without damage in both channel conduction and non-conduction modes. To investigate their damage mechanism, anatomical investigations were performed on two failed devices, which revealed damage had taken place between gate and source.
Sentaurus TCAD simulations included device models and Spice electric models as well as parasitic components, taking their effects into consideration during mixed-mode transient simulations.
SiC MOSFET reliability depends heavily on two parameters, blocking voltage and gate voltage. The blocking voltage determines how much current can pass through during short circuit conditions while gate voltage influences power dissipation and thermal runaway risks. As junction temperature rises, blocking voltage may increase leading to device degradation; for optimal design to prevent these problems it would be beneficial to utilize a common mode rejection optocoupler such as Broadcom ACPL-4800 which helps remove high common mode noise that might otherwise cause false driving of SiC power semiconductors during switching.
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