A New PTC Resistor for Power Applications

Abstract

A new positive temperature coefficient (PTC)resistor and its properties are described which utilizes the metal-insulator solid-state transition in (V,Cr) <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> 0 <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> . At a transition temperature of 80°C, for example, the specific resistivity of a ceramic body exhibits a · rapid increase to a value 100 times higher than that at 20°C, which is typically 1.5x 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\Omega</tex> cm. Due to this low resistivity, thermistors with resistance values between at least 0.1 m <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\Omega</tex> and 0.1 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\Omega</tex> can be manufactured which can carry rated currents substantially higher than 200 A or lower than 2 A, respectively. The construction of the new device is described, and typical properties and applications are illustrated.