You can't help but admire the unheralded fuse.
Fuses are small heroic devices. They come in all forms and sizes, but they all have the role of being a sacrificial device designed to protect an electrical circuit when too much current is drawn than its design allows. They're the Secret Service detail of electrical engineering. If a fuse blows and the circuit remains unharmed, it has done its job right.
In the days of fuses fitted into cartridges or fuse boxes, you had to remove what was left of this small hero when a fuse blew. The spent fuse might be discolored, cloudy, maybe with a melted or broken metal piece inside. The small hero was discarded, unceremoniously thrown into the trash, but it had done something noble.
Today's fuses can be more discrete, maybe surface-mounted, sometimes embedded, and out-of-sight. But their function remains the same—protect the circuit at all costs.
In this week's New Tech Tuesdays, we pay tribute to a new generation of heroic fuses by featuring three different types that still put their lives on the line to protect valuable electric circuits.
Bourns MF-MSHT PTC Resettable Fuses will do their job covertly. These fuses are ideal for overcurrent surge protection of consumer electronic equipment. For example: If some headbanging Queen music comes on and you must crank up the audio, a resettable fuse will protect the tweeter when the amplifier delivers more power to the speakers than the tweeter could tolerate. They're also ideal for communication and security applications. The fuses are AEC-Q200 qualified, meaning they provide robust resettable fault protection for industrial transportation. The MF-MSHT series offers a broader standard high-temperature polymeric positive temperature coefficient device (PPTC) for engineers with high working temperature and power-rating requirements. They're compliant with the AEC-Q200 Rev-D Stress Test Qualification for passive components in automotive applications.
Texas Instruments TPS2640 42V 2A eFuses are also compact but versatile power path protection devices. They're the Dikembe Mutombo of eFuses—virtually nothing gets past them. (Mutombo is known as one of the NBA’s best shot-blockers; surely you’ve seen the finger-wag commercials). These eFuses are capable of withstanding and protecting power loads from positive and negative supply voltages up to ±42V. The eFuses have a reverse current blocking feature that makes the devices suitable for systems with voltage holdup requirements during power fail and brownout conditions. They're used for Human Machine Interface (HMI) power protection in industrial automation settings. They're also found in fire safety systems, electronic thermostats, video doorbells, industrial PCs, and elevators.
Littelfuse PICO® II 521 AEC-Q200 Very Fast-Acting Fuses come in a sub-miniature package, encapsulated in an epoxy-coated body, so you might not actually see it do its job. But it's there. Fast-acting are the most common fuses and are ideal for secondary protection of battery-management systems and space-constrained applications. The fuses are also AEC-Q200 qualified and meet Littelfuse's automotive qualifications.
Our devices have always needed fuses to protect from current overloads. Today, they're more diverse in design to protect even more diverse electrical devices. Through their design evolution, they still have one objective—protection. These Bourns, TI, and Littelfuse fuses carry on the proud tradition of fuses sacrificing themselves to protect the device.
Tommy Cummings is a freelance writer/editor based in Texas. He's had a journalism career that has spanned more than 40 years. He contributes to Texas Monthly and Oklahoma Today magazines. He's also worked at The Dallas Morning News, Fort Worth Star-Telegram, San Francisco Chronicle, and others. Tommy covered the dot-com boom in Silicon Valley and has been a digital content and audience engagement editor at news outlets. Tommy worked at Mouser Electronics from 2018 to 2021 as a technical content and product content specialist.