TransGuard®
AVX Multilayer Ceramic Transient Voltage Suppressors
GENERAL DESCRIPTION
The AVX TransGuard® Transient Voltage Suppressors (TVS)
with unique high-energy multilayer construction represents
state-of-the-art overvoltage circuit protection. Monolithic
multilayer construction provides protection from voltage
transients caused by ESD, lightning, NEMP, inductive switching, etc. True surface mount product is provided in EIA
industry standard packages. Thru-hole components are
supplied as conformally coated axial devices.
TRANSGUARD® DESCRIPTION
TransGuard® products are zinc oxide (ZnO) based ceramic
semiconductor devices with non-linear voltage-current characteristics (bi-directional) similar to back-to-back zener diodes.
They have the added advantage of greater current and energy
handling capabilities as well as EMI/RFI attenuation. Devices
are fabricated by a ceramic sintering process that yields a
structure of conductive ZnO grains surrounded by electrically
insulating barriers, creating varistor-like behavior.
The number of grain-boundary interfaces between conducting electrodes determines “Breakdown Voltage” of the
device. High voltage applications such as AC line protection
require many grains between electrodes while low voltage
requires few grains to establish the appropriate breakdown
voltage. Single layer ceramic disc processing proved to be a
viable production method for thick cross section devices
with many grains, but attempts to address low voltage
suppression needs by processing single layer ceramic disc
formulations with huge grain sites has had limited success.
AVX, the world leader in the manufacture of multilayer
ceramic capacitors, now offers the low voltage transient
protection marketplace a true multilayer, monolithic surface
mount varistor. Technology leadership in processing
thin dielectric materials and patented processes for
precise ceramic grain growth have yielded superior energy
dissipation in the smallest size. Now a varistor has voltage
characteristics determined by design and not just cell sorting
whatever falls out of the process.
Multilayer ceramic varistors are manufactured by mixing
ceramic powder in an organic binder (slurry) and casting it
into thin layers of precision thickness. Metal electrodes are
deposited onto the green ceramic layers which are then
stacked to form a laminated structure. The metal electrodes
are arranged so that their terminations alternate from one
end of the varistor to the other. The device becomes a
monolithic block during the sintering (firing) cycle providing
uniform energy dissipation in a small volume.
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