Apex Microtechnology has developed a family of devices incorporating silicon carbide (SiC) MOSFET technology, improving"> Apex Microtechnology has developed a family of devices incorporating silicon carbide (SiC) MOSFET technology, improving">

SiC enables high power density in a compact package

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Apex Microtechnology has developed a family of devices incorporating silicon carbide (SiC) MOSFET technology, improving performance and power density.

Power applications are moving towards solutions with a smaller footprint and increased efficiency. To increase power density, which in turn allows the device to be housed in a smaller package, SiC is a good candidate to replace silicon in discretes and power modules. Due to their superior properties, SiC MOSFETs are widely used in power applications where high switching frequency, voltage, current, and efficiency are required.

Their ability to operate at higher junction temperatures than supported by silicon also allows SiC devices to achieve better thermal management, which is another advantage for downsizing the chip.

Discrete components and high-power silicon-based modules normally require cooling solutions based on large heat sinks, which affects the size of the overall solution. On the other hand, SiC offers the ability to deliver unprecedented levels of power density in small footprint packages without compromising thermal management.

Silicon carbide

Compared to silicon, SiC offers several advantages, such as its lower on-resistance over temperature and current levels. A low RDS (enabled) results in better current/voltage performance and lower switching losses. Even though the cost of SiC is higher than that of silicon, its reduced thermal load, simpler cooling and higher reliability compensate for this disadvantage.

Based on these considerations, Apex – a supplier of monolithic, hybrid and open-frame analog power components for a wide range of industrial, test and measurement, medical, aerospace, semi-cap and military applications – has developed new products exploiting the properties of SiC. These products include the SA110, a half-bridge switch module with integrated gate driver, and the SA310, a three-phase power switch module with integrated gate driver.

Proper design allows you to effectively highlight all the properties of SiC. When designing its high-power devices, Apex has carefully considered the effect of noise (which can exceed on-state resistance), trace inductance, and trace resistance. Figure 1 shows the block diagram of the Apex SA310KR, a three-phase SiC-based power module with integrated gate driver.

Figure 1: Block diagram of the SA310KR (Source: Apex Microtechnology(

One of the most demanding challenges Apex faced when designing SiC-based power devices was the co-packaging of the MOSFET driver with the MOSFET gate drivers. Due to the high switching frequency, which is a major capability offered by SiC, the current slew rate (di/dt) is very high. This requires careful routing of the traces on the PCB, avoiding the possible formation of noise or interference between adjacent traces (crosstalk).

Also, at higher switching frequencies, the skin effect is not negligible, as it can reduce the cross section of the input/output connections of the package, thus increasing the electrical resistance. These potential issues have been addressed by Apex by using advanced thick film technology on the substrate, printing the traces twice to thicken them and reduce their impedance.

Another benefit of Apex’s co-packaging solution is that the gate drivers are located very close to the SiC MOSFETs, reducing the effect of inductance in the gate, which becomes predominant at higher switching rates. . By paying extra attention to thermal paths, packaging, and materials, the company was able to achieve excellent thermal management, according to Apex. This allows, for example, the SA110 to dissipate 89 W of power, while operating in a temperature range of –40˚C to 125˚C.

The SA110, available in a space-saving 12-pin Power SIP (DP) package, features integrated gate drive control, a very high switching frequency (400 kHz max), and a current of continuous output of 28 A in the grade A variant. It is suitable for applications such as AC/DC and DC/DC converters, power factor correction (PFC) and motor drives.

The SA310, delivered in a 16-pin Power DIP (KR) package, incorporates three independent isolated half-bridges, which provide up to 80 A peak output current under direct microcontroller or DSC control. Built on a thermally conductive but electrically isolated substrate to provide the greatest versatility and ease of heat dissipation, the SA310 meets the requirements of applications such as motor control (BLDC), variable frequency drives, DC converters /AC, inverters, test equipment, and IRM main coil power supplies.

Both devices provide protective capabilities, such as undervoltage lockout and active Miller blocking, to reduce switching noise and improve reliability.

Summit SA111

The Arizona-based company recently announced the SA111, a high-power SiC-based half-bridge module that offers high levels of power density in a compact proprietary PQ package.

Available in a SMD package just 20 × 20 mm, the SA111 (Figure 2) can provide continuous output currents of 32 A, handle supply voltages of up to 650 V, and achieve switching frequencies of up to at 1 MHz (remaining in the safe zone). operating area). The surface mount enclosure has high thermal efficiency and top cooling. This allows users to optimize the layout of the board, placing the heatsink directly above the device.

Figure 2: The new Apex SA111 (Source: Apex Microtechnology)

The SiC half-bridge power module is the ideal solution for applications such as MRI gradient coil drives, magnetic bearings, motor drives, test equipment, server fans, PFCs and converters AC/DC and DC/DC. The SiC MOSFETs also allow the SA111 to withstand higher thermal stresses, handling junction temperatures up to 175°C.

Featuring an integrated gate driver, undervoltage lockout, and active Miller lockout, the SA111 SiC power module is a fully integrated solution for increased device control and protection . SiC greatly improves thermal management, as less heat is generated and therefore there is less need for cooling of the module itself and the module can be made smaller. Similarly, the module power supply can be smaller and dissipate less heat and probably also be cheaper.

With its surface mount package and exceptionally small footprint, the SA111 allows designers to maximize board space, enabling the use of multiple devices in circuit designs with high power density requirements. Sample units of SA111PQ are currently available for qualified customer applications, with a ramp-up of mass production volume planned for summer 2022.

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