At the time of powering on an electronic device such as a switch-mode power supply (SMPS) or an inverter, the device is charged with an instantaneous abnormal current with a high peak. It is called an inrush current, and without protection, it may destroy a semiconductor device or have a harmful effect on the service life of a smoothing capacitor. NTC thermistors are used as ICLs (inrush current limiters) to protect circuits of electrical and electronic devices against inrush currents easily and effectively.