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. By effectively integrating this functionality into a single device the varistors require much less PCB real-estate and significantly reduce component placement costs.
Varistors offer many electrical advantages over zener diodes, including multiple strike capability without degradation, higher in rush current capability, faster turn-on-time, and inherent EMI/RFI attenuation. The varistor is also suitable for protecting devices from induced slow speed transient voltages and currents as well as ensuring negligible degradation in signal integrity.
Automotive Series devices have palladium-silver terminations, DC and rms operating voltages of 16 Vdc and 14 Vrms in general with one device offering 34 Vdc and 30 Vrms, leakage current of 100 µA or under, maximum peak current up to 1200 A (8 x 20 µs), mean power dissipation of 0.030 W or less, and a transient energy rating of 0.6 to 12 Joules (10 x 1000 Ľs). Case sizes are 1206, 1210, 1812, and 2220. Clamping voltage is 40 V in general with one device offering 77 V.
