Driving silicon carbide MOSFETs – ADI & Microsemi joint reference design
The dual SiC MOSFET driver reference design provides design guides enabling faster time to market for engineers using Microsemi’s SiC MOSFETs and supports the transition to Microsemi’s next generation SiC MOSFETs. The Design’s documentation neatly summarises some of the key issues;
* The slew rate at the output of a SiC half bridge can be much higher than with silicon. SiC power stages can easily achieve a dV/dt of 35 kV/μec or more. This affects the design of the gate drive signal isolation and EMI mitigation. It creates potential issues with the method of implementation of parts of the system, such as the gate power DC-DC function. The intention of this board is to provide an off-the-shelf test solution which addresses these issues.
* SiC MOSFETs are normally driven at higher asymmetrical gate voltages when compared to silicon MOSFETs. Typically they are driven at –5 V to 20 V. Lower positive voltages can be used if
the resulting higher device on-resistance is acceptable. Lower negative drive voltages can be used, possibly down to zero.
The reference design describes a highly isolated SiC MOSFET dual-gate driver switch to provide a means for evaluating SiC MOSFETs in a number of topologies. This includes modes optimized for half-bridge switching with synchronous dead- time protection; and asynchronous signal transfer with no protection. It can also be configured to provide concurrent drive with the requirement to study unclamped inductive switching (UIS) or double pulse testing. The reference design was developed for Microsemi SiC MOSFET discrete devices and modules and serves as an engineering tool for the evaluation of its portfolio of SiC devices. The board supports the modification of gate resistor values to accommodate most Microsemi discretes and modules. The logic functions associated with driving the FETs are implemented in a Microsemi (formerly Actel) FPGA.
“The dual SiC MOSFET driver reference design not only enables Microsemi customers to accelerate their product development efforts, but also accommodates the roll-out of our next-generation SiC MOSFETs to ensure a smooth transition for the end user,” said Jason Chiang, strategic marketing manager for Microsemi. “Customers taking a holistic view at power electronics design can utilize our new SiC driver solution to select the best driver and components for their designs, with the ability to scale to their specific SiC MOSFET needs.”
The dual SiC MOSFET driver reference design is intended for a wide range of end markets and applications, including aerospace (actuation, air conditioning and power distribution), automotive (hybrid/electric vehicle powertrains, electric vehicle battery chargers, DC-to-DC converters, and energy recovery), defence (power supply and high power motor drive), industrial (photovoltaic inverters, motor drives, welding, uninterruptible power supply, switched-mode power supply, induction heating and oil drilling) and medical (MRI and X-ray power supply).
Analog Devices collaborates with Microsemi as part of the Accelerate Ecosystem, designed to reduce time to market for end customers and time to revenue for ecosystem participants. Microsemi’s Accelerate Ecosystem brings together leading silicon, intellectual property (IP), systems, software and design experts to deliver validated board and system-level solutions for end customers.
Analog Devices’ isolated gate drivers with DESAT and other protection features provide strong gate drive capability (6A) coupled with robust electrical isolation, critical for long life and safe operation in high voltage power conversion systems. The company’s isolated gate driver portfolio offers designers performance and reliability advantages over designs employing optocouplers or pulse transformers. Utilizing Analog Devices’ iCoupler® technology, the isolated gate driver series offers a number of key benefits in the high voltage and high switching speed applications that Wide Band Gap devices and specifically SiC MOSFETS enable. These include superior propagation delay of better than 50 nsec with channel-to-channel matching of less than 5 nsec, common mode transient immunity (CMTI) of better than >100 kV/µsec and capability to support lifetime working voltages of up to 1500V DC in a single package.
Analog Devices; www.analog.com/en/products/power-management/isolated-gate-drivers.html / www.analog.com
Microsemi; www.microsemi.com/product-directory/mosfet/3539-sic-mosfet#documentation / www.microsemi.com
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