Power Electronics

World’s First Chip Multilayer Ceramic PTC Thermistor

Murata Electronics has developed a ceramic PTC thermistor (POSISTOR) with the world's first multilayered structure. Murata's PRG21 series is the smallest in the industry measuring only 2 mm x 1.25 mm x 0.9 mm, which allows for resistance at 0.2 Ω with a non-operating current of 0.5 A (at an ambient temperature of 60°C). This series was designed primarily for use in USB equipment, power supply circuits and PC-related electronics.

The PRG21 series chip multilayer ceramic PTC thermistor provides low resistance under normal conditions to prevent signal attenuation and power consumption. These PTC thermistors provide a self-reset function, allowing the resistance to be restored to the original low level after the cause of overcurrent is removed and heat generation stops. Unlike other fuses, Murata's PTC thermistor will not melt, therefore enabling it to be used repeatedly as a circuit protection component.

Murata's monolithic structure is specifically designed to achieve miniaturization. By pursuing state-of-the-art pulverizing and firing technology, Murata was able to fuse together the base metal and ceramics without oxidation. This technology enabled Murata to provide a thermistor whose characteristics exceed the limit of those using conventional monoplate structure. Furthermore, the PRG21 series provides high thermal stability and reliability, which can substantially expand the application range of circuit protection components. The series does not contain lead and can be mounted with lead-free solder, which makes reflow soldering at 260°C max applicable.

For more information, visit www.murata.com.

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