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Apex Microtechnology has developed a family of integrated devices silicon carbide (SiC) MOSFET technology that improves performance and power density.
Power applications are moving towards solutions with lower footprint and higher efficiency. To increase the power density, which in turn allows the device to be housed in a smaller package, SiC is a good candidate for replacing silicon in discrete power supplies and modules. Due to their superior properties, SiC MOSFETs are widely used in power applications that require high switching frequency, voltage, current and efficiency.
Their ability to operate at bonding temperatures higher than those withstood silicon also allows SiC devices to achieve better heat control, which is another advantage for shrinking the size of the matrix.
Silicon-based high-power discrete modules and modules typically require cooling solutions based on bulky radiators that affect the size of the overall solution. On the other hand, SiC makes it possible to deliver unprecedented levels of power density in small footprint packets without compromising heat management.
Compared to silicon, SiC offers several advantages, such as its lower resistance to temperature and current levels. Low RDS (included) leads to better current versus voltage performance and lower switching losses. Although the cost of SiC is higher than that of silicon, its reduced heat load, easier cooling, and greater reliability compensate for this disadvantage.
Starting with these considerations, Apex – a supplier of powerful analog monolithic, hybrid and open frame components for a wide range of industrial, test and measurement, medical, aerospace, semi-caps and military applications – has developed new products using SiC properties. These products include the SA110, a half-bridge switching module with integrated port driver, and the SA310, a three-phase power switching module with integrated port driver.
Proper design allows you to effectively emphasize all the properties of SiC. When designing its high-power devices, Apex has carefully considered the effect of parasites (which can exceed the resistance when turned on), trace inductance and trace resistance. Figure 1 shows the block diagram of the Apex SA310KR, based on a SiC three-phase power supply module with integrated port driver.
One of the most challenging challenges Apex faces during the design of SiC-based power supplies is the joint packaging of the MOSFET driver with MOSFET port drivers. Due to the high switching frequency, which is one of the main options offered by SiC, the current growth rate (di / dt) is very high. This requires careful routing of traces on the PCB location, avoiding possible noise or interference between adjacent traces (cross noise).
In addition, at higher switching frequencies, the skin effect is not negligible, as it can reduce the effective cross-sectional area of the input / output connections of the package, increasing the electrical resistance. These potential problems have been solved by Apex by using advanced thick film technology on the substrate, double printing the traces to thicken them and reducing their impedance.
Another advantage of the Apex co-packaging solution is that the gate drivers are located very close to SiC MOSFETs, thus reducing the effect of inductance in the shutter, which becomes noticeable at higher switching speeds. By paying extra attention to thermal roads, packaging and materials, the company has managed to achieve excellent heat management, according to Apex. This allows, for example, the SA110 to dissipate 89 W of power while operating in the temperature range of -40˚C to 125˚C.
Available in a small 12-pin Power SIP (DP) package, the SA110 has integrated gate drive control, a very high (400-kHz max.) Switching frequency and a 28 A continuous class A output current. Suitable for applications such as AC / DC and DC / DC converters, power factor correction (PFC) and motor drives.
The SA310, available in a 16-pin Power DIP (KR) package, integrates three independent isolated half-bridges that provide up to 80 A peak output current under direct microcontroller or DSC control. Built on a heat-conducting but electrically insulated substrate to provide maximum flexibility and ease of cooling, the SA310 meets the requirements of applications such as motor control (BLDC), variable frequency drives, DC / AC converters, inverters, test equipment, and basic supplies for magnetic resonance imaging.
Both devices provide protective capabilities, such as low-voltage blocking and active Miller tightening, to reduce switching noise and improve reliability.
The Arizona-based company recently announced the SA111, a high-power SiC half-bridge module that provides high levels of power density in a compact proprietary PQ package.
Available in an SMD package of only 20 × 20 mm, the SA111 (Figure 2) can provide a continuous output current of 32 A, control supply voltages up to 650 V and achieve switching frequencies up to 1 MHz (remaining in safe operating zone). ). The surface mount package has high thermal efficiency and top cooling. This allows users to optimize the layout of the board by placing the heatsink directly on the device.
The SiC half-bridge power supply module is the ideal solution for applications such as MRI gradient coils, magnetic bearings, motor drives, test equipment, server fans, PFC and AC / DC and DC / DC converters. SiC MOSFETs also allow the SA111 to withstand higher thermal stresses, controlling connection temperatures up to 175˚C.
Featuring an integrated port driver, low voltage blocking and active Miller grip, the SA111 SiC power supply module is a fully integrated solution for increased control and protection of the device. SiC significantly improves heat management as less heat is generated and thus there is less need for cooling of the module itself and the module can be smaller. Similarly, power to the module may be less and dissipate less heat and may also be cheaper.
Thanks to its surface mount package and extremely small footprint, the SA111 allows designers to maximize the area of the board, allowing the use of multiple devices in circuits with high power density requirements. SA111PQ test units are currently available for qualified customer applications, with an increase in mass production planned for the summer of 2022.