SiC JFETs – The ideal circuit protection solution

The UJN & UJ3N series are high-performance SiC normally-on JFET transistors. This series exhibits ultra-low on resistance (RDSON) and gate charge (QG) allowing for low conduction and switching loss. The device normally-on characteristics with low RDS(ON) at VGS = 0 V is also ideal for current protection circuits without the need for active control.  The devices are also commonly used in series connection with a Si-MOSFET as robust ‘supercascodes’, which give all the advantages of wide band-gap technology with very high operating voltages and easy gate drive.


  • 650 V & 1200 V device options

  • Low on-resistance: RDSon maximum of 80mΩ

  • Current limiting: rapid current decrease due to self-heating, limiting I2t

  • Normally-on JFETs: VTH invariant with temperature

  • Peak TJ > 600°C

SiC JFET Selector Guide

Part Number Package V RDS(on) typ Id max
ID New Part Number Package V RDS(on) typ Id max Data Sheet SPICE Model Buy Now
1 UJN1205K TO247 1200 45 38
2 UJN1205Z Die 1200 45 38
3 UJN1208K TO247 1200 80 21
4 UJN1208Z Die 1200 80 21

Design Resources

Full Product Selector Guide

Reliability & Package Data

Normally-On JFET limits current flow from a surge event

Ability to handle T (junction) > 600ºC

Back-to-back normally-on JFETs support bidirectional current limiting


Low series resistance, excellent current limiting behavior

Normally-on JFETs create self-powered two-terminal fact acting circuit breakers


High Side Switch (DC Breaker)


Reliability & Package Data

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