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Do you remember the bad old days when household “consumer unit” fuses were pieces of wire stretched between two terminals and when they blew, you were lucky to be alive, have your house wiring intact (especially if some “tool” had previously replaced a fuse with something like a nail), and scrambling around in the dark looking for a torch and some fuse wire?

If you don’t then you’re very lucky to be living in the age of the resettable RCD, which affords you much greater protection and the convenience of getting your connected home back on line at the flick of a switch.

If you do remember such times, you’ll appreciate the fact that Protected FETS are now being deployed to bring these kinds of protection, active monitoring, and convenience to automotive and industrial applications.

With the dramatic increasing in the number of electrical and electronic systems in vehicles today, reliability has to increase significantly if the vehicle as a whole is going to work reliably over its lifetime.

This old style fuse and relay box was a good step forward in the 1970s, but mechanical relays and replaceable fuses have their limitations in dirty, demanding, and vibration prone environments, especially on a dark night and tucked in the most inaccessible areas under a dashboard or bonnet. Burnout like this picture was not uncommon, due to the limited protection of a simple fuse, and spade connections that could corrode and become high resistance and lead to malfunction or local heating.

Time then to consign the mechanical relay and fuse to history in auto and industrial control applications, with the use of advanced protected field effect transistors “PROFETS” and “HITFETS” from Infineon, who have used their years of expertise in these applications to bring, convenience, reliability, efficiency, monitoring, and safety, to the complex electronic systems around us.

HITFETS, or Highly integrated temperature protected Mosfets, have been around for twenty years and are used today as low-side switches to control many applications in vehicles where electric motors are required like door locks, heating and ventilation, electric parking brakes, as well as mechanical relay replacement. The devices are equipped with temperature, short circuit and overload protection, and designed for harsh ESD environments. The latest HitFet+ family also have programmable slew rates and increased monitoring enabling them to be used in a wider field of consumer and industrial applications like, HVAC, Vending, Access control, vacuum systems, printing, hydraulic valve drivers etc.









Complementing the HITFET low side switch family in the battle against unreliability, are their Hi-Side switch relatives PROFET 12V & PROFET 24V , which also provide integrated protection and diagnostic functions, but their ultra-low resistance (1-2.5mOhm) mean they can drive high current loads up to 40A DC in 12V circuits (such as heating) and power distribution applications (trailers, screen clearing, seat heaters, relay replacement and fan control) particularly where high switching cycles are required. In these types of applications they bring increased monitoring of short, overload, and thermal protection, while increasing efficiency of up to 7x over traditional relays.

Also, lest we forget the lessons of the past, unlike the old fuses/relays, these can be manually or remotely reset, or even auto reset when a fault like an over temperature condition goes away. Cleverly Infineon have tried to maximise pin compatibility too to make upgrading and uprating across vehicles /products as pain free as possible.

RS Stocks >80 of these products today, alongside over 400 Infineon “CoolMos” devices, with more being continually added) to help our customers design better solutions.

Product Group Manager - Semiconductors

14 Aug 2017, 15:11