New 4mΩ SiC JFET Ideal for Circuit Breakers

Qorvo has recently introduced the industry's first 4 milliohm silicon carbide (SiC) junction field effect transistor (JFET) in a standard TOLL leadless package. The Qorvo 750V 4mΩ SiC JFET is specifically designed for circuit protection applications, such as solid-state circuit breakers, where low resistance, superior thermal performance, small size, and reliability are crucial.

The JFET technology, acquired through United SiC, features a 'normally on' characteristic, making it well-suited for circuit breakers. Qorvo is already planning to release a 1200V version and another variant with integrated analog protection circuitry to cater to diverse application needs.

With an impressive on resistance RDS(on) of just 4 milliohm, the UJ4N075004L8S offers the lowest on-resistance in the 650V to 750V class of power devices in standard discrete packages. This low RDS(on) not only reduces heat generation significantly but also, when combined with a compact TOLL package, results in a solution size that is 40% smaller than competing devices in TO-263 packages.

This small footprint allows the UJ4N075004L8S to fit perfectly within the space-constrained dimensions of modern electromechanical circuit breakers, eliminating the need for a heat sink. According to Qorvo, this feature can expedite the shift from electromechanical circuit breakers to semiconductor-based solid-state circuit breakers (SSCBs).

Andy Wilson, product marketing and business development expert for JFETs at Qorvo, highlighted the advantages of using JFETs in circuit protection applications. He mentioned, "There's been a lot of innovation in circuit breakers, but at the core, the mechanical contact has remained unchanged for over 70 years. Moving to a solid-state solution allows for faster current interruption and eliminates arc faults."

Wilson also emphasized the importance of additional components like Gate drivers, microcontrollers, and connectivity in building smart circuit breakers with JFETs. These components play a crucial role in load management, current monitoring, and ensuring system reliability.

One of the major challenges in designing solid-state circuit breakers is managing heat effectively. As these breakers need to coexist with legacy electromechanical counterparts in existing panels without additional cooling, minimizing resistance becomes essential. The UJ4N075004L8S addresses this challenge by offering a low effective resistance in a compact package.

Looking ahead, Qorvo plans to expand its JFET offerings with variations like a 1200V device, tailored for specific architectural requirements. The company aims to continue driving innovation in the field of SiC JFET technology to meet the evolving needs of circuit protection applications.