August 10, 2021

    This blog post was first published by United Silicon Carbide (UnitedSiC) which joined the Qorvo family in November 2021. UnitedSiC is a leading manufacturer of silicon carbide (SiC) power semiconductors and expands Qorvo's reach into the fast-growing markets for electric vehicles (EVs), industrial power, circuit protection, renewables and data center power.

    If you haven’t found it yet, UnitedSiC’s free-to-use web-based FET-Jet calculator has been a revelation – it makes selection of a SiC FET and SiC Schottky diode for your power design a breeze. You just select from drop-down menus what topology of AC-DC or DC-DC converter you want to use, isolated or non-isolated. Changing between continuous, critical, or discontinuous modes is automatic and seamless. You set the input, output, power required and you’re all set to play with the selection of SiC FETs and Schottky diodes available from the UnitedSiC range. The tool instantly calculates overall efficiency, component losses by dynamic and conduction contributions and current stress levels. You can even specify paralleled devices, multiple converter ‘legs’ and external heatsink performance for a prediction of junction temperatures.

    The new V2 version significantly streamlines the SiC FET and Schottky diode selection process and has doubled the number of different topologies to choose from to 26 across the converter types.

    Losses and temperature rises are now displayed as bar charts for an instant visual indication of the conduction, turn on and turn off loss contributions. A really useful new addition is recommendations for gate resistors RGon and RGoff for different devices and drive voltages, along with suggested snubber component values for optimized control of voltage overshoot.

    FET-Jet calculator selectable conversion topologies selection interface image
    Figure 2: FET-Jet selectable conversion topologies

    The new topologies included invite some extra choices as well. As an example, the calculator for the complex ‘Three level ANPC Voltage Source Inverter’ topology in the AC-DC area allows the selection of PWM strategy: LF middle, HF middle, and Max ON, while three modulation schemes: sine-triangle, space-vector, and discontinuous 60° PWM are selectable options. The number of paralleled devices, and in some topologies, the number of legs/phases, can be increased without limit – try clicking up the number and see the bar charts dynamically update, to get a feel for the benefits and trends of losses and temperatures. Don’t worry; warnings appear if invalid selections are made. Other new features are links to a part marking decoder, indicative waveform images, and the option now to download a PDF file of the calculator results for your records.

    FET-Jet calculator V2 is now an even better tool to select devices and visualize their performance almost instantly, enabling quick and accurate first-pass designs. The tool is regularly updated with the latest parts from UnitedSiC, including Gen4 SiC FETS with their outstanding performance in hard- and soft-switched topologies. We know what you’re like – engineers are going to select outrageous combinations. 1000 paralleled FETs in 50 legs in a boost converter. There’s no registration, so give it a try!


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