TMOV and iTMOV Varistor Series The Littelfuse TMOV and iTMOV thermally protected varistors represent a new development in integrated circuit protection. Both versions are comprised of radial leaded MOVs (Metal Oxide Varistors) with an integrated thermally activated element designed to open in the event of overheating due to the abnormal overvoltage, limited current, conditions outlined in UL 1449. The iTMOV varistor differs from the TMOV varistor by the inclusion of a third party lead for the purpose of indicating that the MOV has been disconnected from the circuit. This lead facilitates connection to monitoring circuitry. The TMOV and iTOMV varistors offer quick thermal response due to the close proximity of the integrated thermal element to the MOV body. The integrated configuration also offers lower inductance than most discrete solutions resulting in improved clamping performance to fast over-voltage transients. Additionally, TMOV and iTMOV varistors are wave solderable, thus simplifying end product assembly by reducing the expense and rework associated with hand soldering operations. The TMOV and iTMOV varisors are both recognized surge suppression components to UL 1449. The TMOV and iTMOV varistor’s integrated thermal element, in conjunction with appropriate enclosure design, helps facilitate TVSS module compliance to UL 1449 for both cord connected and permanently connected applications. TMOV and iTMOV varistors are compatible for use with industry standard wave-solering processes or recommended hand-soldering methods.