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Varistors from AVX reduce component count for ESD protection in CAN applications

22nd January 2008

AVX

ES Admin

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CAN Series varistors from AVX Corporation are specifically designed to provide ESD protection in controlled-area-network (CAN) applications, predominantly in automotive electronics. The zinc-oxide (ZnO) based, multilayer ceramic varistors feature non-linear, bi-directional voltage-current characteristics similar to back-to-back Zener diodes and an EMC (electromagnetic compatibility) capacitor in parallel. This “equivalent” capacitor ensures inherent EMI/RFI attenuation.

Available as 0603 discretes or 0405 and 0612 arrays with two and four elements respectively, the varistors offer significant advantages over diodes in CAN networks. These include space savings, higher ESD capability at 25 kV contact, higher in-rush current of 4 A (8 x 20 µs) and a FIT rate of under 0.1 failures (per billion hours).

Multilayer ZnO varistors offer nanosecond response times and compared to diodes demonstrate a greater capability of withstanding repetitive ESD high voltage discharge without degradation. A single ZnO varistor also replaces the diode, capacitor and resistor array on multiplex node applications, significantly reducing component count and space requirements. Varistors also offer inherent EMI/RFI attenuation.

The varistors are specified with 0.015 J (10 x 1000 µs) transient energy rating, 22 pF maximum capacitance, 2 µA maximum leakage current at working voltage, as well as a DC working voltage of up to 18 V and AC working voltage of up to 14 V.

AVX can also design and manufacture custom versions to specific performance and environmental characteristics not available in the standard product range.