High-surge varistors

12 August 2015 Circuit & System Protection

A new series of EPCOS multilayer varistors (MLV) is being offered by TDK with high surge current capability, ranging from one surge of up to 5000 A to ten surges of up to 3500 A, with a pulse of 8/20 μs and an operating voltage of up to 65 V d.c.

The SMD components are available in case sizes EIA1210 through EIA2220 and require significantly less space than wired types or semiconductor-based solutions.

A new high-performance ceramic material set and an improved component design have made the further miniaturisation possible. This means that, in comparison with conventional technologies, current densities of three times higher can be achieved. On this basis, TDK now manufactures protection components in the EIA 1210 case size that offer the same performance as existing EIA 2220 types, which are three times larger. Despite their compact design, the maximum energy absorption for EIA 2220 components is about 15 J for a pulse of 2 ms.

In addition, the rugged new MLVs are highly resistant to thermo-mechanical stress. They offer extremely high surge current capability even at 125°C, a temperature at which other technologies can only be operated with derating. The protection components are designed for lead-free reflow soldering processes.

Applications include power supplies for telecommunication systems and power-over-Ethernet (PoE) systems.

For more information contact Yolandi de Beer, Avnet South Africa, +27 (0)11 319 8600, [email protected], www.avnet.co.za

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