PPTC (Polymeric Positive Temperature Coefficient Thermistor) is also known as resettable fuse. It has very low resistance under normal working status, no impact on the working circuit. The response speed of PPTC is from few dozen ms to few seconds level. It is proportional to the current value. Yageo provides SMD (case size: 0603 ~ 2920) and DIP package types for the usage in different applications.