Qorvo Introduces Alternative to Mechanical Circuit Breakers

This article was shared with us from All About Circuits' sister website EEPower.

Qorvo has introduced a 750 V, 4 milliohm (mΩ), silicon carbide (SiC), junction field effect transistor (JFET) in a compact surface-mount TO-leadless (TOLL) package with superior circuit breaker design and performance. The North Carolina-based company unveiled the product at the 2024 Power Conversion and Intelligent Motion (PCIM) conference in Nuremberg, Germany.

"We are in the early stages of the next revolution in circuit breaker technology," Andy Wilson, business development manager, told EEPower. “Solid-state circuit breakers must fit in the existing boxes with no heat sinks or forced air cooling to be successful in the market. The JFET meets the three requirements: low R for low heat, small size, and robust.”

The robust JFETs developed provide circuit protection and can turn off at high inrush currents in case of a circuit fault. The JFET’s normally-on nature allows its seamless integration into systems where the switch must turn off under fault conditions.

 

Qorvo’s Andy Wilson and EEPower’s Dale Wilson view JFETs at PCIM 2024. Image used courtesy of EEPower

 

Solid-State Circuit Breakers Advantages

Solid-state circuit breakers (SSCBs) have several advantages over traditional mechanical circuit breakers.

• Faster operation. SSCBs can interrupt faults in microseconds, significantly faster than mechanical breakers, which take several milliseconds to trip. This rapid response helps prevent damage to equipment and improves system stability.
• No arcing. SSCBs do not have moving contacts, eliminating the problem of arcing that can damage equipment in mechanical breakers during switching operations.
• Remote operation. SSCBs can be reset remotely through wired or wireless connections, unlike mechanical breakers, requiring manual resetting on-site.
• Programmable current ratings. SSCBS’ current ratings are programmable and adjustable, while mechanical breakers have fixed current ratings.
• Compact size and weight. SSCBs are more compact and lightweight than mechanical breakers, making them suitable for space-constrained applications like electric vehicles and aircraft.
• Longer operating life. With no moving parts, SSCBs have a longer operating life and are not subject to wear and tear like mechanical breakers.
• Temperature flexibility. SSCBs can operate at higher temperatures than mechanical breakers, and their operating temperature can be set as required.
• Current limiting capability. Some SSCBs can limit fault currents, which is not possible with mechanical breakers.

While SSCBs offer these advantages, their main challenges include higher costs, limited voltage/current ratings, and potential thermal management issues compared to mechanical breakers.

 

Qorvo’s Design for Low On-Resistance

Qorvo’s UJ4N075004L8S design offers the industry’s lowest on-resistance among the 650 V to 750 V class of power devices in standard discrete packages. This low R_DS(on) significantly reduces heat generation and, when coupled with a compact TOLL package, enables a solution size 40% smaller than competing devices. 

 

The UF3N170400B7S JFET.  Image used courtesy of Qorvo 

 

Among the key features and benefits of Qorvo’s power devices are:

• The ultra-low on-resistance of 4 mΩ is 4-10 times lower than competing Si MOSFETs, SiC MOSFETs, and GaN transistors, enabling higher efficiency and reduced power losses.
• The 750 V rating provides a significantly enhanced design margin for managing voltage transients, 100-150 V higher than alternative technologies.
• The TOLL package is 30% smaller in footprint and half the height of comparable D2PAK packages, making it ideal for space-constrained applications like solid-state circuit breakers.
• Its industry-leading 0.1°C/W thermal resistance from junction to case enables effective heat dissipation.
• The high current ratings are 120 A DC up to 144°C case temperature and 588 A pulsed current for 0.5 ms, providing robustness and immunity to transient overloads.

Qorvo SSCB’s advantages over traditional circuit breakers include faster fault interruption in microseconds, compared to milliseconds for mechanical breakers, improved system stability, and equipment damage prevention. In addition, because there are no arcing or moving contacts, wear and tear is eliminated, and operating life is increased.

Qorvo's 750 V 4 mΩ SiC JFET in the TOLL package represents a significant advancement in solid-state circuit breaker technology, offering superior performance, efficiency, and design flexibility compared to traditional mechanical breakers and other semiconductor solutions. According to the company, the UJ4N075004L8S is now available for sampling and will enter full production in Q4 2024, accompanied by additional JFET options, including 750 V with 5 milliohm and 1200 V with 8 milliohm ratings, all in TO-247 packaging.