MicroPower Direct SiC DC-DC Converter Offers High Isolation

Safety and reliability are among power electronics systems' most important engineering design considerations, including MOSFET bridges. These circuits are widely used in applications like motor control and power converters. They demand careful attention to factors like isolation voltage and clearance between conductors to prevent the risk of electrical hazards.  

MicroPower Direct has launched its wide gap, 5 kV isolation silicon carbide (SiC) MOSFET driver and DC/DC converter, designed to mitigate electrical hazards associated with MOSFET bridge circuits.

MSC200LHI IGBT driver and DC/DC converter. Image used courtesy of MicroPower Direct

Gate Drivers and Electrical Safety

A power MOSFET is a voltage-controlled switching component in various systems like power supply circuits and motor drives.

To activate an N-channel MOSFET, a voltage must be applied to the gate relative to the MOSFET's source, which is often grounded. A large voltage difference is also needed between the device's drain and source to force current across the induced channel.

Typically, the gate voltage ranges from 0.5-10V, whereas the drain voltage may be hundreds of volts. Therefore, isolation in gate driver MOSFET circuits is necessary to ensure safety by electrically separating the high-voltage sections from the low-voltage control sections. This separation prevents voltage transients or faults from damaging sensitive components and ensures the circuit’s proper functioning. The stronger the isolation, the greater the device's reliability.

Another important factor in gate drivers is the creepage distance. Creepage and clearance distances are established industry norms specifying the minimum separation between any two exposed metal contacts to avert arcing across air and surfaces, respectively. These parameters are crucial in system design, particularly in configurations incorporating an isolation barrier between high and low-voltage domains. 

Typical connection diagram of MSC200LHI. Image used courtesy of MicroPower Direct

In integrated circuits, creepage and clearance distances are determined by measuring the closest contacts with a notable voltage differential between them. Adequate creepage and clearance distances are essential to maintain isolation between high- and low-voltage components. Creepage distance can reduce electrical breakdown risk and ensure reliable circuit operation. Greater creepage distances lend to improved device reliability and safety.

Redefining Reliability

MicroPower Direct’s MSC200LHI high-isolation DC/DC converters are specifically designed for use in SiC gate drive circuits with an optimal driving frequency of 200 kHz. These converters feature an impressive I/O isolation of 5 kV, surpassing the industry standard of 3 kV. They have a significantly wider electrical clearance/creepage distance of 14.74 mm compared to the typical 8 mm standard.

This wider gap enables the units to maintain a continuous barrier and withstand a voltage of 1,700 V even under damaged conditions. The MSC200LHI offers six models with inputs of 12, 15, or 24 VDC and outputs of +15 V/-4 V or +20 V/-5 V. Standard features include continuous short circuit protection, up to 87% efficiency, low isolation capacitance of only 3.5 pF, and a high MTBF (mean time between failures) of over 3.5 Mhours. These converters are packaged in a compact, 10-pin SIP case, meeting UL94-V0 requirements, and are approved to EN 62368 (UL) standards.

MSC200LHI efficiency. Image used courtesy of MicroPower Direct

With operations ranging from -40°C to +105°C without heat sinking, the devices also provide reliable cooling through free-air convection, which is particularly important in high-power applications.

Powering the Future

MicroPower Direct's MSC200LHI is a useful component for high-speed gate drive circuits needing high levels of safety and efficiency. By greatly exceeding industry standards in creepage and isolation voltage, the MOSFET driver is ideal for high-power switching applications, such as those used in industrial machinery and electric vehicles.