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To accomplish these goals, they need to look closely to see how they can optimize their power conversion solutions to reduce conduction and switching losses, maintain good thermal performance, reduce overall form factor, and lower electromagnetic interference (EMI). They must also ensure the solution of choice is capable of meeting the production part approval process (PPAP) and be qualified to AEC-Q101. To meet these challenges, designers can turn to a variety of silicon carbide (SiC) power MOSFETs, SiC Schottky diodes, gate driver ICs, and power modules. This article briefly reviews how SiC technology can increase efficiency and reliability and reduce cost, compared to classic silicon (Si) approaches. It then looks at packaging and system integration options for SiC before introducing several real-world examples from onsemi and showing how designers can best apply them to optimize SiC power MOSFET and gate driver performance to meet the energy infrastructure challenge. SiC vs Si SiC is a wide bandgap (WBG) material, with a bandgap of 3.26 electron volts (eV) compared with the 1.12 eV bandgap of Si. It also offers 10X the breakdown field capability, over 3x the thermal conductivity, and can operate at much higher temperatures compared with Si. Those specifications make SiC well-suited for use in energy infrastructure applications (Table 1). Properties Si 4H-SiC 150 600 Table 1: The material properties of 4H-SiC compared with Si make SiC well-suited for use in energy infrastructure applications. (Image source: onsemi) The higher breakdown field allows thinner SiC devices to have the same voltage rating as thicker Si devices, and the thinner SiC devices have a correspondingly lower on-resistance and higher current capability. The mobility parameter of SiC is on the same order of magnitude as Si, making both materials usable in high-frequency power conversion, which supports compact form factors. Their higher thermal conductivity means that SiC devices experience a lower temperature rise at higher current levels. The operating temperature of SiC devices is limited by packaging factors such as wirebonds, not SiC material characteristics. As a result, the selection of the optimal packaging style is an important consideration for designers when using SiC. SiC’s material characteristics make it a superior choice for many high-voltage, high-speed, high-current, and high-density power conversion designs. In many cases, the question is not whether to use SiC, the question is what SiC packaging technology provides the optimal performance and cost tradeoffs. Designers have three basic packaging choices when using SiC power technology; discrete devices, intelligent power modules (IPMs), or power integrated modules (PIMs), each of which offers a unique set of cost and performance tradeoffs (Table 2). For example: Discrete devices are generally preferred when cost is a primary consideration, such as consumer applications. They also support dual sourcing and have long lifetimes. IPM solutions reduce design time, have the highest reliability and are the most compact solutions for moderate power levels. PIMs can support higher power designs with good power densities, reasonably fast time to market, a wide variety of design options, and more opportunities for dual sourcing, compared with IPMs. Table 2: Comparison of integration features and tradeoffs when choosing between discrete, IPM and PIM SiC packaging solutions. (Image source: onsemi) Hybrid Si/SiC IPMs While it’s possible to develop solutions using only SiC devices, it’s sometimes more cost-effective to use hybrid Si/SiC designs. For example, the NFL25065L4BT hybrid IPM from onsemi combines fourth-generation Si IGBTs with a SiC boost diode on the output to form an interleaved power factor correction (PFC) input stage for consumer, industrial and medical applications (Figure 1). This compact IPM includes an optimized gate drive for the IGBTs to minimize EMI and losses. Integrated protection features include under−voltage lockout, over−current shutdown, thermal monitoring, and fault reporting. Other features of the NFL25065L4BT include: 600 volt/50 ampere (A) two-phase interleaved PFC Optimized for 20 kilohertz (kHz) switching frequency Low thermal resistance using aluminum oxide direct bond copper (DBC) substrate Integrated negative temperature coefficient (NTC) thermistor for temperature monitoring Isolation rating of 2500 volts root mean square (rms)/1 minute UL certification Figure 1: The NFL25065L4BT IPM forms an interleaved PFC stage using fourth-generation Si IGBTs with a SiC boost diode on the output. (Image source: onsemi) SiC PIMs For solar inverters, EV charging stations, and similar applications that can benefit from using a SiC-based PIM to maximize power delivery with reduced footprint and smaller overall volume, designers can turn to the NXH006P120MNF2PTG . This device comprises a 6 milliohm (mΩ), 1200 volt, SiC MOSFET half−bridge and an integrated NTC thermistor in an F2 package (Figure 2). Package options include: With or without pre−applied thermal interface material (TIM) Solderable pins or press-fit pins Figure 2: The NXH006P120MNF2PTG integrated power module comes in an F2 package with press-fit pins. (Image source: onsemi) These IPMs have a maximum operating junction temperature of 175 degrees Celsius (°C) and require external control and gate drivers. The optional press-fit technology, also called cold welding, provides a reliable connection between the pins and plated-through holes on the pc board. Press-fit provides simplified assembly without soldering and produces a gas-tight, low resistance, metal-to-metal connection. SiC Schottky diodes SiC Schottky diodes can be used in combination with IPMs, or in 100% discrete designs, and they provide better switching performance and higher reliability compared to Si diodes. SiC Schottky diodes, like the 1700 volt/25 A NDSH25170A , have no reverse recovery current, excellent thermal performance, and temperature-independent switching characteristics. These translate into higher efficiency, faster switching frequencies, higher power densities, lower EMI, and easy paralleling, all of which contribute to reducing solution size and cost (Figure 3). Features of the NDSH25170A include: 175°C maximum junction temperature 506 millijoules (mJ) avalanche rating Non-repetitive surge current up to 220 A and repetitive surge currents up to 66 A Positive temperature coefficient AEC-Q101 qualification and PPAP capability Figure 3: The 1700 volt/25 A NDSH25170A SiC Schottky diode has no reverse recovery current, excellent thermal performance, and temperature-independent switching characteristics. (Image source: onsemi) Discrete SiC MOSFETs Designers can combine discrete SiC Schottkys with onsemi's 1200 V SiC MOSFETs , which also have superior switching performance, lower ON resistance, and higher reliability compared to Si devices. The compact chip size of SiC MOSFETs produces low capacitance and gate charge. Combined with their low ON resistance, the lower capacitance and gate charge help increase system efficiency, enable faster switching frequencies, increase power densities, lower electromagnetic interference (EMI), and allow smaller solution form factors. For example, the NTBG040N120SC1 is rated for 1200 volts and 60 A, and comes in a D2PAK−7L surface-mount package (Figure 4). Features include: 106 nanocoulombs (nC) typical gate charge 139 picofarads (pF) typical output capacitance 100% avalanche testing AEC-Q101 qualification Figure 4: The NTBG040N120SC1 SiC MOSFET is rated for 1200 volts/60 A, has an on resistance of 40 mΩ, and comes in a D2PAK−7L surface-mount package. (Image source: onsemi) SiC MOSFET gate driver Gate drivers for SiC MOSFETs, such as the onsemi NCx51705 line, deliver a higher drive voltage than drivers for Si MOSFETs. It takes a gate voltage of 18 to 20 volts to fully turn on a SiC MOSFET, compared with less than 10 volts needed to turn on an Si MOSFET. In addition, SiC MOSFETs require −3 to −5 volts of gate drive when switching the device off. Designers can use the NCP51705MNTXG low-side, single 6 A high-speed driver optimized for SiC MOSFETs (Figure 5). The NCP51705MNTXG delivers the maximum rated drive voltage to enable low conduction losses, and it provides high peak currents during turn-on and turn-off to minimize switching losses. Figure 5: Simplified schematic showing two NCP51705MNTXG driver ICs (center right) driving two SiC MOSFETs (right) in a half-bridge topology. (Image source: onsemi) Designers can use the integrated charge pump to generate a user-selectable negative voltage rail to deliver higher reliability, improved dv/dt immunity, and faster turn-off. In isolated designs, an externally accessible 5-volt rail can power the secondary side of digital or high-speed optoisolators. Protection functions in the NCP51705MNTXG include thermal shutdown based on the junction temperature of the driver circuit, and bias power undervoltage lockout monitoring. Eval board and SiC gate drive considerations To speed up the evaluation and design process, designers can use the NCP51705SMDGEVB eval board (EVB) for the NCP51705 (Figure 6). The EVB includes an NCP51705 driver and all the necessary drive circuitry, including an on−board digital isolator and the ability to solder any SiC or Si MOSFET in a TO−247 package. The EVB is designed for use in any low−side or high−side power switching application. Two or more of these EVBs can be configured in a totem pole drive. Figure 6: The NCP51705SMDGEVB EVB has holes (top left) to connect an SiC or Si power MOSFET, and includes the NCP51705 driver (U1, center left) and the digital isolator IC (right center). (Image source: onsemi) Minimization of pc board parasitic inductance and capacitance is important when using the NCP51705 gate driver with an SiC MOSFET (Figure 7). Some pc board layout considerations include: The NCP51705 should be as close as possible to the SiC MOSFET, with particular attention being paid to short traces between VDD, SVDD, V5V, charge pump, and VEE capacitor and the MOSFET. The trace between VEE and PGND should be as short as possible. There needs to be separation between the high dV/dt traces and the driver input and DESAT to avoid abnormal operation that can result from noise coupling. For high-temperature designs, thermal vias should be used between the exposed pad and the outer layer to minimize thermal impedance. Wide traces need to be used for OUTSRC, OUTSNK and VEE. Figure 7: Recommended pc board layout for the NCP51705 to minimize parasitic inductance and capacitance for driving SiC MOSFETs. (Image source: onsemi) Conclusion SiC plays an important role in helping designers meet the demands of a growing number and variety of energy infrastructure applications. Designers can now use SiC devices to design more efficient high-voltage, high-speed, high-current power conversion designs that result in smaller solutions sizes and higher power densities. However, the selection of the optimal packaging style is important to get the maximum benefit from designing with SiC. As shown, there are a range of performance, time to market and cost tradeoffs to be considered when choosing between discrete devices, IPMs and PIMs. Also, when using discrete devices or PIMs, the selection of the SiC gate driver and the optimal pc board layout are critical in order to achieve reliable and efficient system performance. Recommended Reading Related Videos Publish Date: 2024-02-15 Related Product Highlight Wide Bandgap Technologies onsemi offers a robust range of highly efficient & intelligent power components providing a full WBG ecosystem, including a variety of EliteSiC devices to choose from. Find the best fit for your application at DigiKey today! Power Integrated Modules onsemi's power integrated module is an electronic device integrating mostly power switching devices to maximize power delivery in a reduced footprint. UHD Power Conversion ON Semi offers a complete portfolio of power products covering a variety of power conversion applications, from MOSFETs, IGBTs, power modules and more. ON Semi is equipped to support engineers in assisting in their creative design innovations. Related Articles and Blogs Wide Bandgap Semiconductors Are Reshaping the Transportation World The entire transportation sector is undergoing a radical transformation with solutions for electric and hybrid cars and cleaner mass transportation. Wide Band Gap Semiconductors in Aerospace and Satellite Applications Wide Band Gap semiconductors bring several advantages in power conversion, such as increased power density and efficiency, and reducing system size and weight. About this author Jeff Shepard Jeff has been writing about power electronics, electronic components, and other technology topics for over 30 years. He started writing about power electronics as a Senior Editor at EETimes. He subsequently founded Powertechniques, a power electronics design magazine, and later founded Darnell Group, a global power electronics research and publishing firm. Among its activities, Darnell Group published PowerPulse.net, which provided daily news for the global power electronics engineering community. He is the author of a switch-mode power supply text book, titled “Power Supplies,” published by the Reston division of Prentice Hall. Jeff also co-founded Jeta Power Systems, a maker of high-wattage switching power supplies, which was acquired by Computer Products. Jeff is also an inventor, having his name is on 17 U.S. patents in the fields of thermal energy harvesting and optical metamaterials and is an industry source and frequent speaker on global trends in power electronics. He has a Masters Degree in Quantitative Methods and Mathematics from the University of California. About this publisher Thank you! Keep an eye on your inbox for news and updates from DigiKey! Please enter an email address I agree to receive marketing emails from DigiKey. I understand that I can withdraw consent at any time. Please review our Privacy Notice . 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