Patent ID: 7598840

Claim:
A metal oxide varistor having thermal cut-off function comprising: a metal oxide varistor body having a first lateral side and a second lateral side, the metal oxide varistor body heating up when exposed to voltage strikes; a first lead, one end thereof electrically coupled to the first lateral side and the other end opposite to the one end of the first lead adapted to couple to a source of current; a thermal cut-off fuse comprising a first fuse end and a second fuse end, the thermal cut-off fuse having a predetermined melting point at which the thermal cut-off fuse melts and interrupts current flow therethrough; a second lead, one end thereof directly and electrically coupled to the first fuse end of the thermal cut-off fuse and the other end opposite to the one end of the second lead adapted to couple to the source of current; wherein the metal oxide varistor further comprises a silver electrode area, and one end of the silver electrode area is formed on and electrically coupled to the second lateral side, and the other end opposite the one end of the silver electrode area is electrically coupled to the second fuse end of the thermal cut-off fuse, whereby the current is permitted to flow through the first lead, the metal oxide varistor body, the silver electrode area, the thermal cut-off fuse and the second lead when the thermal cut-off fuse is held below the predetermined melting point and the current is interrupted when the thermal cut-off fuse goes above the predetermined melting point and melts due to the heat provided by the metal oxide varistor body, under which case the metal oxide varistor is protected from thermal runway.