Littelfuse
Littelfuse is an American electronics manufacturer specializing in circuit protection, power-control, sensing, switching, and semiconductor products.
Last updated August 25, 2026
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Overview
Littelfuse is an American electronics manufacturing company founded in Chicago in 1927 by Edward V. Sundt. The company began with a small protective fuse intended to prevent electrical failures in diagnostic equipment. Sundt had previously worked at General Electric and Stewart-Warner, where he encountered equipment failures caused by excessive current. The company’s name was created after Sundt’s proposed trademark, “Little fuse,” was rejected as too descriptive; he rearranged letters to form “Littelfuse.” The business was incorporated as Littelfuse, Inc. in 1938 and became publicly traded in 1962. During its early decades, it built a position in electrical protection and expanded manufacturing beyond its original Chicago base. Its product portfolio broadened in the 1970s, including the Littelites line of electronic indicator lights and the AutoFuse blade-type automotive fuse. Introduced in 1976, AutoFuse became an important automotive product and is described as the first blade-type fuse used in automobiles. The company later pursued legal protection against counterfeit versions of the product and obtained a United States International Trade Commission exclusionary order in 1983. Littelfuse spent part of its history under corporate ownership. Tracor acquired the company in 1968, and Westmark Systems purchased Tracor and its Littelfuse subsidiary in 1987. After Tracor entered bankruptcy proceedings in 1991, Littelfuse was spun off and reincorporated. It completed a second initial public offering in 1991 under the leadership of Howard Witt. The company subsequently expanded its manufacturing, engineering, distribution, and sales presence across Europe, Asia, and South America. Its headquarters returned to Chicago from Des Plaines, Illinois, in 2008, alongside a major restructuring of its manufacturing footprint. The modern Littelfuse portfolio is organized around electronics, industrial, and automotive applications. Products include fuses, circuit breakers, overvoltage suppressors, gas discharge tubes, solid-state relays, electronic switches, solenoids, battery-management devices, protective relays, power-monitoring equipment, automotive sensors, and semiconductor components. Through acquisitions, the company added capabilities in automotive and industrial sensing, heavy-duty vehicle power management, switchgear, electrical-shock protection, power semiconductors, and electromechanical switching. The acquisition of Hamlin in 2013 strengthened its sensor business, while the 2017 acquisition of IXYS also brought Zilog and expanded the company’s semiconductor activities. Littelfuse serves equipment manufacturers, automotive companies, industrial operators, electrical distributors, and electronics customers. Its products are generally designed to protect circuits, control electrical energy, detect operating conditions, isolate faults, or manage power in demanding applications. The company has operated more than 40 sales, distribution, manufacturing, and engineering facilities across the Americas, Europe, and Asia. It remains an active, diversified supplier whose historical fuse business has developed into a broader electrical and electronic protection platform.
History
Edward V. Sundt founded Littelfuse in Chicago in 1927 after observing that electrical failures could disrupt diagnostic equipment. Drawing on experience at General Electric and Stewart-Warner, Sundt developed a compact protective fuse designed to regulate current and prevent equipment damage. The company initially operated as Littelfuse Laboratories. Sundt’s preferred name, “Little fuse,” was not accepted as a trademark because it was considered too generic, so the spelling was altered to produce the Littelfuse name. The company was incorporated under the Littelfuse, Inc. name in 1938. It became a public company in 1962 while Sundt remained chairman. In 1963, headquarters moved from Chicago to Des Plaines, Illinois. Sundt retired as chairman in 1965 and was succeeded by Thomas Blake. Tracor acquired Littelfuse in 1968, making it a wholly owned subsidiary while retaining Blake as president. During the 1970s, Littelfuse expanded its manufacturing capacity with facilities in Watseka, Illinois, and Piedras Negras, Mexico. It also broadened beyond conventional fuses with Littelites, electronic indicator lights used in machinery, appliances, computers, and office equipment. In 1976, the company developed AutoFuse, a blade-style automotive fuse that became an important product in vehicle electrical systems. Counterfeiting of AutoFuse products led to regulatory action, and in 1983 the United States International Trade Commission issued an exclusionary order barring imports of counterfeit blade-type fuses. Westmark Systems acquired Tracor and its Littelfuse subsidiary in 1987. Tracor later filed for bankruptcy in 1991 and spun off Littelfuse. The company reincorporated in November 1991, with Howard Witt serving as president and chief executive officer. Littelfuse completed its second initial public offering that year. Through the 1990s, it expanded into Europe and Asia and established a distribution and engineering center in São Paulo, Brazil, extending its reach into South America. The company entered a more diversified expansion phase from the late 1990s onward. Acquisitions added suppression products, semiconductor capabilities, circuit and overvoltage protection, industrial protection systems, automotive switches and sensors, heavy-duty vehicle power-management products, monitoring equipment, switchgear, and power semiconductors. Key transactions included Harris Suppression Products, Semitron, Teccor, the WICKMANN-related businesses, Cole Hersee, Selco, Accel, Terra Power Systems, Hamlin, SymCom, and other industrial and automotive specialists. The 2016 purchase of TE Connectivity’s circuit-protection business and selected ON Semiconductor divisions further strengthened its protection and semiconductor portfolio. The 2017 acquisition of IXYS also brought Zilog into the Littelfuse group. Gordon Hunter became president and chief executive officer at the end of 2004. In 2008, Littelfuse reorganized manufacturing by closing 16 smaller plants and opening six larger facilities, while moving its headquarters from Des Plaines back to Chicago. During the early 2010s, the company received repeated product and supplier awards, including recognition from Consulting-Specifying Engineer, Arrow Electronics, TTI, and the Chicago Innovation Awards. In 2017, David Heinzmann succeeded Hunter as chief executive officer. Later acquisitions continued to extend the company’s electromechanical, semiconductor, switching, and electrical-safety capabilities. These included Monolith Semiconductor in 2018, Carling Technologies in 2021, C&K Switches in 2022, Western Automation Research and Development in 2023, and Basler Electric in 2025. Littelfuse’s present business therefore extends well beyond traditional fuses: it supplies technologies that protect, monitor, switch, sense, and control electrical energy across automotive, electronics, industrial, transportation, energy, and heavy-equipment markets.
- 2025
Basler Electric is acquired
[1]Littelfuse adds protection-relay capabilities through the acquisition of Basler Electric.
- 2023
Western Automation Research and Development is acquired
[1]The acquisition adds electrical-shock protection technologies.
- 2022
C&K Switches is acquired
[1]Littelfuse expands its electromechanical switch portfolio.
- 2021
Carling Technologies is acquired
[1]The transaction adds switching and electromechanical circuit-breaker capabilities.
- 2017
IXYS and Zilog join Littelfuse
[1]The IXYS acquisition expands Littelfuse’s power-semiconductor activities and brings Zilog into the group.
- 2013
Hamlin acquisition expands sensor capabilities
[1]The acquisition adds automotive, industrial, and consumer sensor products.
- 2008
Manufacturing is restructured and headquarters return to Chicago
[1]The company closes 16 smaller plants, opens six larger facilities, and moves its headquarters from Des Plaines to Chicago.
- 1991
Littelfuse is spun off and completes a second IPO
[1]Following Tracor’s bankruptcy, Littelfuse is spun off, reincorporated, and returned to the public market.
- 1983
Counterfeit AutoFuse imports are excluded
[1]The United States International Trade Commission issues an exclusionary order concerning counterfeit blade-type fuses.
- 1976
AutoFuse blade-type automotive fuse is developed
[1]Littelfuse develops what is described as the first blade-type automotive fuse.
Products and positioning
A global supplier of electrical and electronic protection, sensing, switching, and power-management technologies for automotive, electronics, industrial, transportation, energy, and heavy-equipment applications.
Circuit protection · 1927
Circuit-protection fuses
Littelfuse’s foundational product family protects electrical and electronic circuits from overcurrent and related fault conditions. The portfolio serves electronics, automotive, industrial, and electrical-distribution applications, ranging from compact device protection to larger industrial systems.
Automotive circuit protection · 1976
AutoFuse
AutoFuse is Littelfuse’s blade-type automotive fuse platform. Developed in 1976, it was designed for vehicle electrical systems and became one of the company’s best-known automotive offerings. The product’s popularity also led to documented counterfeiting and trade-enforcement action.
Electronic indicators · 1974
Littelites
Littelites are electronic indicator lights introduced for use in industrial and office machinery, household appliances, and computers. The line marked an early expansion beyond conventional current-protection devices into electrical status and interface components.
Automotive and industrial sensing
Sensors
Littelfuse supplies sensing technologies for automotive, industrial, and consumer applications. The company substantially expanded this capability through acquisitions including Hamlin, Accel, and U.S. Sensor, adding magnetic, position, temperature, and related detection products.
Semiconductors and embedded control
Zilog products
Through Zilog, acquired as part of the IXYS transaction, Littelfuse has offered microprocessors and related embedded-control products. This capability complements its broader power-semiconductor and electronic-control portfolio.
Switching and power management
Switches and electromechanical products
The company’s switching portfolio includes electronic switches, heavy-duty vehicle switches, electromechanical switches, and circuit breakers. Acquisitions such as Cole Hersee, Carling Technologies, and C&K Switches expanded its presence in commercial vehicles, industrial equipment, and control interfaces.
Brand decisions
2025
Acquisition of Basler ElectricM&ABackground
Littelfuse continued developing its industrial electrical-protection portfolio.
Action taken
The company acquired Basler Electric, a designer and manufacturer of protection relays.
Aftermath
The transaction added protection-relay technologies to Littelfuse’s industrial offering.
2023
Acquisition of Western Automation Research and DevelopmentM&ABackground
Littelfuse sought additional capabilities in electrical safety and shock protection.
Action taken
The company acquired Western Automation Research and Development Limited.
Aftermath
The acquisition added electrical-shock protection devices and related engineering capabilities.
2022
Acquisition of C&K SwitchesM&ABackground
Electromechanical switching was an expanding component of Littelfuse’s product strategy.
Action taken
Littelfuse acquired C&K Switches.
Aftermath
The transaction broadened Littelfuse’s electromechanical switch offering.
2021
Acquisition of Carling TechnologiesM&ABackground
Littelfuse continued expanding its switching and electromechanical product capabilities.
Action taken
The company acquired Carling Technologies, a manufacturer of switches and electromechanical circuit breakers.
Aftermath
The acquisition strengthened the company’s switching and circuit-breaker portfolio.
2017
Acquisition of IXYSM&ABackground
Littelfuse aimed to increase its presence in power semiconductors and related electronic-control technologies.
Action taken
The company acquired IXYS, thereby also acquiring Zilog.
Aftermath
The transaction added power-semiconductor and microprocessor capabilities to Littelfuse’s portfolio.
2013
Acquisition of HamlinM&ABackground
Littelfuse sought to broaden its circuit-protection business into sensing applications.
Action taken
The company acquired Hamlin, an automotive sensor manufacturer.
Aftermath
The transaction expanded Littelfuse’s automotive, industrial, and consumer sensor offerings.
2008
Manufacturing footprint restructuringStrategyBackground
Littelfuse undertook a broad review of its manufacturing network as it expanded internationally.
Action taken
The company closed 16 smaller manufacturing plants and opened six larger facilities.
Aftermath
The restructuring consolidated production capacity while the company also moved its headquarters back to Chicago.
1983
Trade action against counterfeit blade fusesOtherBackground
The AutoFuse brand was heavily counterfeited, creating a product-authenticity and market-protection issue.
Action taken
Littelfuse obtained a United States International Trade Commission exclusionary order barring imports of counterfeit blade-type fuses.
Aftermath
The order provided a formal mechanism to restrict the importation of infringing products.
1976
Launch of AutoFuseProduct launchBackground
Automotive electrical systems required compact, standardized protection devices suitable for vehicle manufacturing and service applications.
Action taken
Littelfuse developed and introduced the AutoFuse blade-type automotive fuse.
Aftermath
AutoFuse became a significant automotive product and was later the subject of counterfeit-product enforcement.
Recent events
Reported
Littelfuse reports Q3 2026 earnings[2]
Littelfuse reported Q3 2026 revenue of $766.7 million, up 22.7% year on year but below analyst estimates, and adjusted EPS of $5.79, above estimates. It guided to Q4 2026 revenue of $760 million at the midpoint and adjusted EPS of $5.15 at the midpoint.
Reported
Littelfuse launches AK-FL series FlatSuppressX TVS diodes for aviation power systems[3]
Littelfuse announced the launch of the AK-FL series FlatSuppressX transient voltage suppression (TVS) diodes, axial-leaded devices designed to protect high-voltage DC aviation power systems from transient overvoltage while maintaining a flat, low and stable clamping voltage. The series is the first FlatSuppressX TVS diode designed for aviation and eVTOL power protection, offering 6 kA, 8 kA and 10 kA (8/20 μs) current ratings, 100% screening per MIL-STD-750 test methods, and RTCA DO-160 compliance, targeting 270 V-800 V DC aerospace, defense and eVTOL applications.
- Unconfirmed
Reported
Littelfuse launches FlatSuppressX TPSMD-FL TVS diode series for automotive load dump protection[4]
Littelfuse announced the launch of the FlatSuppressX TPSMD-FL series of automotive-grade TVS (transient suppression) diodes, designed to simplify ISO 7637-2 Pulse 5b load dump protection for 12V automotive electronics. The series handles 3000 W peak pulse power in a DO-214AB surface-mount package and is AEC-Q101 qualified.
Reported
Littelfuse/C&K launches TSC Series Toggle Safety Covers[5]
Littelfuse, Inc. (NASDAQ: LFUS) announced the launch of the Littelfuse/C&K TSC Series Toggle Safety Covers, designed to prevent accidental actuation of toggle switches in critical control systems. The covers use a spring-loaded mechanism, a stainless steel faceplate, and ABS covers in multiple colors, fitting standard 12.0 mm mounting holes and switch levers up to 25 mm. They are targeted at industrial control equipment, commercial and off-road vehicles, marine systems, aerospace platforms, and military equipment, and are available in bags of 50 and cartons of 1,000 through authorized Littelfuse distributors.
Reported
Littelfuse completes acquisition of Carling Technologies[6]
Littelfuse completed its previously announced acquisition of Carling Technologies.
- Unconfirmed
Reported
Littelfuse acquires Hartland Controls[7]
Littelfuse announced that it had acquired Hartland Controls, a manufacturer and supplier of electrical components used primarily in HVAC/R and other industrial and control systems applications.
Littelfuse launches Gate Drive Evaluation Platform[8]
Littelfuse launched the Gate Drive Evaluation Platform (GDEV) for evaluating SiC MOSFETs, SiC Schottky diodes and related components under continuous operating conditions.
Sources10 sources
- 1Littelfuseen.wikipedia.org
- 2Littelfuse公布2026年第三季度业绩markets.financialcontent.com
- 3Littelfuse推出用于航空电源系统的AK-FL系列FlatSuppressX瞬态电压抑制二极管finance.sina.com.cn
- 4Littelfuse推出FlatSuppressX TPSMD-FL系列TVS二极管，用于汽车负载突降保护finance.sina.com.cn
- 5Littelfuse/C&K 推出 TSC 系列拨动开关安全护盖n.yam.com
- 6Littelfuse完成对Carling Technologies的收购evertiq.com
- 7Littelfuse收购Hartland Controlsevertiq.com
- 8Littelfuse推出栅极驱动评估平台semiconductor-today.com
- 9Chicago Electronics Maker Littelfuse Acquires HVAC Components Manufacturerthomasnet.com
- 10Littelfuse/C&K推出TSC系列拨动开关安全盖，防止误操作和意外触发finance.sina.com.cn
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