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PTC thermistor selection

  1. Mar 31, 2016 #1
    Hi all, I'm new here so I thought I'd give this a shot.

    I'm developing a relatively high power power electronic system and I want a hardware shutdown for over-temperature without going back and revving my PCB too extensively. One effective way to accomplish this is with a PTC with a sharp Resistance vs Temperature characteristic like so:

    I've actually purchased this kit shown here: http://en.tdk.eu/inf/55/db/PTC/PTC_Sensors_SMD_chips_standard.pdf

    I'm still shopping around but I'm wondering if any of you have experience with PTC selection. Here are my main issues:
    1. NTC's generally won't work for what I'm trying to do because they are relatively linear. Effectively what I want is a temperature triggered switch (like shown characteristic). The linked above was the only family of resistors (EPCOS) that I could find with that property. Does anyone know of any other manufacturers or kits that might have this feature?
    2. The tolerance range of these ones I've found is HUGE (+/-50%). This will become a digital signal at the end of the day so I can work with it but I'd prefer less slop. Once again, does anyone know of any other suppliers I can go to that will have a better control on tolerance?
    3. The nominal values from this kit are very limited (just 110, 470,680,10k) and I'd like more options.

    Basically, I'm still shopping but thought I'd give it a shot in case any of you out there know your PTC's and more importantly your suppliers.

  2. jcsd
  3. Mar 31, 2016 #2


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    A bimetal switch could be an alternative.
    It's simply on/off.
  4. Apr 2, 2016 #3


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