PTC Thermistor

Positive Temperature Coefficient (PTC) thermistor is a type of resistor whose resistance increases significantly with temperature.

• Function: Overcurrent/overtemperature protection, self-regulating heater, motor start assist.
• Behavior: Low resistance at low temp → High resistance at high temp.
• Applications: Resettable fuses (e.g., polymeric PTC), inrush current limiting.
• Types:
  • Ceramic PTC – sharp resistance rise at Curie temperature.
  • Polymer PTC – used as resettable fuse (e.g., Bell Fuse, Littelfuse PolySwitch).

Note: Unlike NTC thermistors, PTCs are not typically used for temperature sensing but for protection and control.