Top 10 circuit protection devices

Circuit protection devices are safety components that are used in every electronic device and system, ranging from the smallest smartphones and wearables to high-reliability applications like automotive and data centers to protect them from failure due to surge events and electrostatic discharge (ESD) strikes as well as overvoltage, overcurrent and overtemperature conditions.

These small, protective devices include ESD protection devices like transient voltage suppressor (TVS) diodes and arrays, surge protectors, fuses and circuit breakers. Over the past year, miniaturization continued to be a key trend, particularly for TVS diodes, driven by a range of end devices from wearables to automotive interfaces.

Circuit protection manufacturers have also focused on enabling these protective devices to withstand the harshest automotive, industrial and avionics applications. Here is a selection of 10 circuit protection devices, introduced in 2023, highlighting these trends. They are not in any particular order.

Ultra-small protectors for mobile and wearables

One space-saving bidirectional TVS diode is the D3V3Z1BD2CSP from Diodes Incorporated. It is designed to protect high-speed data ports from both ESD strikes and surge events. The new TVS diode targets I/O ports in high-performance computing hardware, smartphones, laptops, tablets, computers, displays and gaming consoles.

Diodes said the D3V3Z1BD2CSP does not compromise on either surge protection or low input capacitance, which is typically a design tradeoff in competing devices. The TVS diode has an ultra-low capacitance of 0.3 pF (typical), which ensures signal integrity by not interfering with or impeding high-speed data communication, the company said.

Other features include high peak pulse current (10.5 A typical) and low clamping voltage (5.3 V), which protect I/O ports and their sensitive electronics from transient voltages, reducing the risk of electrical overstress damage from things like frequent hot swapping. The D3V3Z1BD2CSP complies with the IEC61000-4-2 immunity standard, providing ESD protection against ±20-kV air and contact discharges.

The D3V3Z1BD2CSP can be used to protect I/O interfaces, such as USB Type-C, DisplayPort, HDMI and SD Card, with high-speed data rates up to 20 Gbits/s. It is housed in a compact, 0.6 × 0.3 × 0.3-mm DSN0603 WLCSP. In addition, the TVS diode features a wide operating temperature range of –55°C to 150°C for protection in challenging application environments.

Targeting ESD protection of USB4 and Thunderbolt 4, Alpha and Omega Semiconductor (AOS) has developed a TVS diode with an ultra-low reverse working voltage. The new AOZ8S207BLS-01 delivers low capacitance, a fast response time and small packaging.

The AOZ8S207BLS-01 features an extremely low capacitance of 0.15 pF and claims “superior” high-speed data-line protection thanks to the company’s advanced Ultra-Low Breakdown Voltage TVS platform and innovative packaging. A low breakdown voltage is essential for ESD protection devices, AOS said.

The company also reported the AOZ8S207BLS-01 can provide a faster response time compared with conventional snapback devices, enabling it to absorb ESD energy very quickly to avoid damage to the IC and surrounding components. Together, the low capacitance, lower clamping voltage and faster response during an ESD event enable the device to protect the more ESD-sensitive chipsets.

The AOZ8S207BLS-01 is a single-channel device housed in a 0.6 × 0.3-mm leadless SMD package, making it suitable for USB Type-C connectors.

Taiwan Semiconductor’s latest ESD protection devices offer protection up to ±30 kV, thanks to its proprietary bidirectional clamping cell, in an ultra-small DFN0603 package. The new TESD Series of single-channel ESD clamping diodes deliver size and performance specifications for wearable applications.

In addition to wearable applications, the combination of their ultra-small size and ultra-low capacitance makes them suited for other ESD-sensitive applications, including HDMI, display port and high-speed video I/O; USB 3.0 and 3.1; industrial I/O (RS485); SATA and eSATA; and RAID, NAS and SAN systems.

The protection devices are available in versions with 5-V and 3.3-V (max.) operating voltages and provide protection in compliance with IEC61000-4-2 (ESD) to ±20 kV (air/contact) and IEC61000-4-5 (lightning) to 4.5 A (8/20 µs). The series also offers a second 3.3-V model that increases these specs to ±30 kV and 8.2 A, respectively.

The 3.3-V TESDL3V3B23P1Q0 (17 pF) protects control signal lines and power lines on the PCB, as well as serial and parallel ports. Both the 3.3-V TESDH3V3B03P1Q0 (0.2 pF) and 5-V TESDH5V0B03P1Q0 (0.2 pF) are suited for SATA/eSATA, PCI Express, USB3.1/3.0, USB Type-C and DisplayPort interfaces. The devices are RoHS-compliant and halogen-free.

Aimed at USB-C ESD protection and housed in micro packages, TDK Electronics has launched a new series of compact TVS diodes with very low parasitic capacitance values and low clamping voltage required for high-speed USB-C ports, operating at up to 40 Gbit/s with USB4 version 1. These TVS diodes can also be used for other high-speed interfaces, such as Thunderbolt, HDMI, Display Port, FireWire, DVI, SATA or SWP/NFC. Typical applications include smartphones, tablets, notebooks, wearables and network components.

With ultra-low clamping voltage and capacitance, the B74111U0055M060 and B74121U0055M060 TVS diodes feature maximum DC voltages of up to 5.5 V and capacitance values of 0.48 pF and 0.65 pF at 1 MHz, respectively, so that signal integrity is not compromised. They are suitable for the conventional USB 2.0 data bus of USB-C (D+/D–). Their clamping voltages are 3.9 V and 4.0 V, with an I_TLP of 8 A.

Designed for high ESD discharge voltage of up to 15 kV, the TVS diodes are manufactured in compact WLCSP 01005 and WLCSP 0201 packages and are extremely flat, with heights of 100 µm and 150 µm, respectively, enabling them to be easily integrated into USB-C SiP modules. The ESD protection exceeds standard requirements, according to TDK.

Power lines VBUS can be used to transmit a maximum of 100 W at voltages of up to 20 V and currents of 5 A, also requiring safe ESD protection. Within the new TVS family, TDK’s general-purpose diodes include the B74121G0160M060, which features a maximum working voltage of 16 V, and the B74121G0200M060, with a value of 20 V. Clamping voltages are rated at 23 V and 27 V, respectively, at an I_TLP of 8 A. They feature capacitance values of 6 pF and 5 pF, respectively, with high linearity and are rated for ESD contact discharge voltages of 15 kV. They are also designed in the compact WLCSP 0201 form factor with a height of 150 µm.

Protecting automotive electronics

A big growth area for ESD protection is automotive applications, particularly automotive infotainment with numerous high-speed interfaces. Nexperia targets high-speed data lines in interfaces like USB, HDMI, high-speed video links and Ethernet in automotive infotainment applications with its new ultra-low–capacitance ESD protection diodes. The packaging options are designed to minimize the impact on signal integrity.

The new devices include the PESD18VF1BLS-Q, PESD24VF1BLS-Q, PESD30VF1BLS-Q and PESD32VF1BLS-Q in the DFN1006BD-2 package, enabling optical inspection in automotive production lines using side-wettable flanks. The PESD18VF1BBL-Q, PESD24VF1BBL-Q and PESD30VF1BBL-Q devices are also available in the DFN1006-2 package.

Nexperia said all variants are in leadless packages to improve electrical performance and minimize their impact on signal integrity. They offer ESD protection up to ±10 kV according to IEC 61000-4-2, Level 4.

Nexperia’s latest AEC-Q101 automotive-qualified devices offer ultra-low capacitance, as low as a typical 0.28 pF, along with a higher standoff voltage of 18–32 V for placement closer to the connector. They also claim “extremely deep snapback behavior” and a low dynamic resistance of 0.8 Ω for improved system-level robustness and clamping performance in high-speed data interfaces. The ESD protection diodes are offered with and without side-wettable flanks.

Also targeting automotive applications is Vishay Intertechnology Inc.’s two-in-one protection device that combines a rectifier and TVS in a small FlatPAK 5 × 6 package. The company claims the integrated component is the industry’s first standard rectifier and TVS two-in-one device for automotive applications.

The Vishay General Semiconductor R3T2FPHM3 combines a 3-A, 600-V standard rectifier with a 200-W TRANSZORB TVS. The rectifier features a low forward-voltage drop of 0.86 V to reduce power losses and improve efficiency, while the TVS offers a breakdown voltage of 27 V.

“By combining two different technologies in a single package, the dual-chip solution saves PCB space, simplifies layouts and lowers overall costs in these applications,” Vishay said. “When paired in series with a standard TVS, the R3T2FPHM3 offers designers a complete >24-V solution with a low clamping ratio.”

The protection device is suited for high-reliability automotive applications, including secondary protection for sensor units, distributed airbag modules and low-power DC/DC converters in power distribution systems. It provides a wide operating temperature range from –55°C to 175°C.

The R3T2FPHM3 is in compliance with IEC 61000-4-2, air discharge and contact mode and UL 94 V-0 flammability rating for its molding compound. It is also RoHS-compliant and halogen-free. The device is available in an AEC-Q101–qualified version.

Littelfuse Inc. claimed the industry’s first release of AEC-Q200–qualified fuses. These protection devices are designed for the demanding circuit protection needs in compact automotive electronics and EV applications.

The new automotive-grade portfolio includes a range of thin-film fuses, Nano2 fuses, PICO fuses and cartridge fuses, which are all certified to meet the AEC-Q200 Revision E qualifications for fuses for long-term reliability of components used in harsh automotive environments. Offering a wide range of performance, reliability and component options, these fuses offer high I²t values to ensure high inrush current withstand capability and provide circuit protection against abnormal overload and surge conditions.

The AEC-Q200–qualified fuses are suited for a wide range of automotive electronics designs. They include on-board chargers, power distribution units, battery management systems, ignition systems, infotainment and navigation, ADAS, radar and eCall. They can also be used for sensing-line protection and high-voltage DC/DC converters.

Innovations for high-reliability applications

Bourns Inc. has expanded its gas discharge tube (GDT) family with new devices that deliver a higher level of voltage limiting during fast-rising events. Claiming breakthrough overvoltage surge arrestor performance, the Model GDT35 Series offers a significantly higher level of protection against voltage transients caused by lightning or accidental contact with AC power lines, resulting in a faster-responding component.

Bourns said it developed the next generation of GDTs with improved impulse voltage protection and higher surge ratings to meet increased market demand as susceptibility to surges increased with smaller components, calling for smaller and more effective overvoltage protection solutions.

The three-electrode GDTs are based on Bourns’s proprietary, advanced computer simulation techniques, which led to a lower-impulse sparkover component design that reduces stress on downstream components, Bourns said. This enables designers to select smaller and lower voltage-rated components, reducing the bill-of-materials costs.

The key features of the GDT35 series are the high surge rating, lower impulse breakdown and lower capacitance. These devices also feature a unique coplanarity fit that enables the devices to toggle in either direction until a three-point contact is established. It is also reported to deliver “superior” current-handling capability in a small, 5 × 7.2-mm form factor. (See the datasheet for specs by part number.)

Also, the low capacitance (< 0.7 pF) and low insertion loss make the devices suited for protecting industrial equipment and high-speed information and communication technology systems. Other key specs include a DC breakdown voltage range of 75–600 V and an extended temperature range of –55°C to 125°C to meet tough environmental conditions.

The GDT35 Series is UL-recognized and RoHS-compliant. A GDT35 Design Kit for prototyping is available.

Designed for circuit protection in high-speed communication data-line applications like Ethernet, set-top boxes, xDSL, T1/E1 line cards and ISDN, ProTek Devices’ latest TVS hybrid array, the PTA03-3.3ULC, protects against ESD, electrical fast transients (EFTs) and secondary electrical transient threats.

ProTek introduced its first hybrid circuit protection devices in 2022 as replacements for surface-mount metal oxide varistors for household and industrial applications with extended reliability and operational lifetimes.

The high-power and low-capacitance PTA03-3.3ULC TVS hybrid array provides low capacitance—max. 2.4 pF (I/O to I/O)—even at higher temperatures and 2,000-W peak pulse power per line (8/20 µs typical). It features 100 A (2/10 µs) per Bellcore GR1089 (intra-building) and ESD protection greater than 30 kV, contact per IEC 61000-4-2. It also allows for a telecom/diode bridge configuration.

The PTA03-3.3ULC is also compatible with IEC standards 61000-4-2 (ESD): ±15 kV (air), ±8 kV (contact); IEC 61000-4-4 (EFT): 40 A, 5/50 ns; and IEC 61000-4-5 (surge): 70 A, 8/20 µs. It is also RoHS- and REACH-compliant.

The TVS hybrid array is housed in a molded JEDEC SO-8 package with an approximate weight of 70 mg. It has a flammability rating of UL 94V-0. The operating and storage temperature is –55°C to 150°C.

Designed for avionics and other harsh environmental conditions, Schurter has introduced the FRM-A panel-mount fuse holder with a DRM-A SMT fuse. This compact solution measures <15 mm deep behind the panel.

Although the ultra-compact FRM-A fuse holder is originally designed to withstand harsh environmental conditions in the avionics industry and is qualified for use up to 50,000 feet, its compact dimensions and high ingress protection rating of IP67 make it suited for use in any challenging environment, Schurter said.

The FRM-A has successfully passed vibration, shock and salt mist tests according to NF C 20-7XX and IEC 60068-2-XX and is built to UL 4248-1 and CSA C22.2 No. 4248-1. The fuse holder is developed exclusively for use with the SMT DRM-A ceramic fuse.

The DRM-A is a fast-acting ceramic SMT fuse built according to UL 248-14 for avionics applications and uses gold plating on the endcaps to prevent tin whiskers. It features a pre-arcing time rated for an altitude of 50,000 feet, but it is suitable for any application that requires a reliable and robust design. Rated 0.5–8 A at 250 VAC and 125 VDC, the DRM-A meets similar IEC environmental tests as the FRM-A, as well as additional MIL-STD-202 tests.

Used together or the fuse separately, the FRM-A and DRM-A devices can be used in a range of industrial markets, AV/IT applications according to IEC/UL 62368-1 and household appliances according to IEC 60335-1. The fuse holder and fuse combination carry the marks for CE, UKCA, RoHS, China RoHS, UL, Halogen-Free and REACH.