Rohm has recently unveiled their fourth generation of SiC MOSFETs and we at PGC Consultancy and TechInsights have been testing them to see whether or not they meet manufacturer claims.
Yole Group’s Amine Allouche and Poshun Chiu provide insight into ROHM’s business strategies, technological innovations, and product roadmap for Power SiC markets.
High Efficiency
SiC devices have become an increasingly popular choice due to their increased efficiency. One significant application for SiC devices is in traction inverters for electric vehicles (xEVs), where large numbers are required in order to extend cruising range.
Conventional silicon IGBTs cannot compare with these new designs in terms of performance and reliability required for automotive use. ROHM was the first company in the world to mass produce SiC MOSFETs and now boasts an impressive selection of AEC-Q101 compliant devices used in PV inverters, uninterruptible power supplies and PFC sections for electric vehicle chargers.
Trench MOSFETs stand out from conventional planar MOSFETs by virtue of their trench structure, which reduces ON resistance while still offering excellent short-circuit withstand voltage. When combined with lower parasitic capacitance levels and parasitic capacitance reduction benefits, this structure ultimately results in 50% less switching loss when compared with conventional MOSFETs.
High Stability
ROHM’s SiC power devices are engineered to meet the stringent reliability standards required of electric vehicle (xEV) manufacturers. ROHM’s EcoSiC brand leverages silicon carbide – which has recently made waves within the power device industry due to performance far surpassing traditional silicon. ROHM independently develops technologies essential to SiC advancement – wafer fabrication processes, production systems and packaging systems – further solidifying their position as industry leaders.
Due to their manufacturing process, CCS’s second-generation 1200 V, 80 O SiC MOSFET products exhibit stability that surpasses that of Si silicon transistors (Si-MOSFETs) even at high voltages. This is due to effective prevention of stacking fault expansion that could otherwise cause body diode conduction degradation; CCS TDDB tests conducted under conditions which mimic long-term operation have demonstrated this stability, with no failures or fluctuations in characteristics like on resistance being recorded during long-term operation simulated by CCS.
Low On-Resistance
Rohm has reduced cell spacing by up to three, effectively mitigating channel resistance issues that account for as much as 30% of an on-resistance MOSFET with 650V on-voltage rating.
Rohm’s 4th generation devices claim an on-resistance that is up to 40% lower than previous generations, as verified by TechInsights cross-sections. TechInsights cross-sections confirm this – enabling Rohm to shrink their chip sizes while decreasing cost.
Rohm has successfully reduced ON resistance while improving parasitic capacitance and achieving 50% lower switching loss compared to their prior generation of SiC MOSFETs. Short circuit tests of Gen 4 will soon take place at PGC and even their claim that short-circuit withstand time has increased with derating reduction are evidence that these devices represent significant advances.
Low Saturation Current
With the proliferation of IoT devices and high-performance personal electronics like smartphones and computers, more efficient power supplies are necessary. SiC MOSFETs deliver greater efficiency than their silicon counterparts for reduced energy consumption as well as sleeker products with reduced footprint.
ROHM’s 4th generation 650 V SiC MOSFETs feature reduced ON resistance than 3rd generation devices to achieve increased power density and short circuit robustness, and increased power density density. This is accomplished using a new cell layout which maximizes gate and body diode dissipation areas as well as its unique structure which prevents expansion of stacking faults during body diode conduction.
Yole Group’s Poshun Chiu conducted an interview with Akifumi Enomoto, Department Manager for Power Devices Business Strategy of ROHM Group. Together they discussed its strategies and technological innovations within the rapidly expanding Power SiC market. Click here to read their complete conversation.
High Power Density
Rohm will exhibit innovations in power semiconductor devices designed to lower system costs at PCIM Nuremberg trade fair for Power Electronics, Intelligent Motion and Energy Management. As one of the premier providers of wide bandgap power devices with its silicon carbide (SiC) MOSFETs offering excellent voltage stability at high voltages.
Yole’s Amine Allouche and Poshun Chiu meet with Akifumi Enomoto, Department Manager, Power Devices Business Strategy at ROHM about their strategies to capitalize on the rapidly expanding Power SiC market.
Enomoto details how ROHM’s Gen 3 SiC MOSFETs employ an innovative two-dimensional lattice of gates to nearly double gate density within each cell and reduce overall package size. Furthermore, these devices boast small forward voltage and low resistance that drastically decrease switching losses for electric vehicles while helping lower costs overall. Automotive designers will find ROHM Gen 3 SiC MOSFETs invaluable when creating powerful motor drives with reduced power loss and extended battery-operated ranges.
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