Yes. I've used them for about 10 years.

Russell McMahon wrote:
> Excellent resource for polyswitch sourcing & designing.
>
> A Polyswitch (Raychem) / Multifuse (Bournes) / Polyfuse (generic) is a
> self resetting thermal fuse used to provide both overcurrent and over
> temperature protection. Basic principle has a conductive powder
> (typically carbon) embedded in a polymer matrix. When the matrix is
> heated above its phase change temperature by the combination of the
> current through it and the ambient temperature it "swells" and
> separates the conductive particles, thereby causing a significant rise
> in resistance. A much reduced 'holding current" is sufficient to
> maintain heating due to the higher resistance. The device is (usually)
> reset by depowering it and allowing it to cool. (A blast with a CO2
> extinguisher may also work).
>
> Polyswitches are extremely useful, but also very nasty thermo
> mechanical devices. Basic operation is very straight forwards.
> Understanding them fully is an arcane art. They are far from just
> being the basic "trip at X amps / reset when power removed" devices
> they may initially seem top be. Variables which may vary relevantly
> include attack times, current/temperature/time curves, holding and
> trip currents, max allowed tripped voltage  and more.
>
> Excellent Tyco / Raychem Polyswitch page
> Selection guide, catalog, order samples.
> App notes.
> Some links broken.
> Also has links to other Tyco protection systems.
>
>         http://www.circuitprotection.com/polyswitch.asp
>
> Tyco / Raychem documentation
>
>         http://www.circuitprotection.com/literature.asp
>
>
> Extremely good 12 page design guide.
>
>     http://www.circuitprotection.com/06Databook/fundamentals/PSWFundamentals.pdf
>
> Basic overview and useful selector guide
> 4 pages
>
>         http://www.circuitprotection.com/06Databook/PSWFundamentals(80-83).pdf
>
>
>   

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