PolySwitch Telecommunication Resettable PTCs Littelfuse PolySwitch Telecom Resettable PTCs are designed to protect against short-duration high-voltage fault currents typically found in telecom applications. These components help provide protection against damage caused by power cross and power induction surges, as well as help improve the reliability of customer premise and network equipment worldwide. Littelfuse PolySwitch Telecom Resettable PTCs are compatible with high-volume electronics assembly, assist in meeting regulatory equipment requirements, help improve line balance, and are applicable for legacy POTS and modern digital communications equipment. These devices are available in chip, surface-mount, or radial-leaded configurations.