Trisil is a trade name for a
thyristor
A thyristor (, from a combination of Greek language ''θύρα'', meaning "door" or "valve", and ''transistor'' ) is a solid-state semiconductor device which can be thought of as being a highly robust and switchable diode, allowing the passage ...
surge protection device, an electronic component designed to protect electronic circuits from
overvoltage
In electrical engineering, overvoltage is the raising of voltage beyond the design limit of a circuit or circuit element. The conditions may be hazardous. Depending on its duration, the overvoltage event can be transient—a voltage spike—o ...
. Unlike a
transient voltage suppression diode
A transient-voltage-suppression (TVS) diode, also transil, transorb or thyrector, is an electronic component used to protect electronics from voltage spikes induced on connected wires.
Description
The device operates by shunting excess current ...
s, such as Transil, Trisil acts as a
crowbar device, switching ON when the voltage across it exceeds its breakover voltage.
Overview
A Trisil is bidirectional, behaving the same way in both directions. It is principally a voltage-controlled
triac
A TRIAC (triode for alternating current; also bidirectional triode thyristor or bilateral triode thyristor) is a three-terminal electronic component that conducts current in either direction when triggered. The term TRIAC is a genericized trad ...
without gate. The behavior of a Trisil is similar to a
SIDAC, but unlike SIDAC, Trisil devices are commonly used to protect circuits from overvoltage.They act faster and can handle more current. In 1982, the only manufacturer was
Thomson SA
Vantiva SA (formerly Technicolor SA, Thomson SARL, Thomson SA, and Thomson Multimedia) is a French multinational corporation that provides technology products and services for the communication, media and entertainment industries. Headquarter ...
; a successor company,
ST Microelectronics
STMicroelectronics NV (commonly referred to as ST or STMicro) is a European multinational semiconductor contract manufacturing and design company. It is the largest of such companies in Europe. It was founded in 1987 from the merger of two st ...
continues to make the devices.
This type of crowbar protector is widely used to protect telecom equipment from lightning-induced transients and power line-induced currents. Other manufacturers of similar devices include Bourns (TISP) and
Littelfuse (SIDACtor). Instead of relying on the device's natural breakdown voltage, an additional region is fabricated within the device to form a
Zener diode
A Zener diode is a type of diode designed to exploit the Zener effect to affect electric current to flow against the normal direction from anode to cathode, when the voltage across its terminals exceeds a certain characteristic threshold, the ''Z ...
. This provides much tighter control over the breakdown voltage.
Gated versions of these protectors can also be manufactured. In such cases, the gate is connected to the telecom circuit's power supply (via a diode or transistor), causing the device to activate if the transient voltage exceeds the power supply voltage. The primary advantage of this configuration is that the protection voltage follows the power supply voltage, eliminating the need to select a specific breakdown voltage for the protection circuit.
See also
*
Transil
*
Zener diode
A Zener diode is a type of diode designed to exploit the Zener effect to affect electric current to flow against the normal direction from anode to cathode, when the voltage across its terminals exceeds a certain characteristic threshold, the ''Z ...
References
External links
Overvoltage protection''Trisil/Transil Comparison'', ST Application Note (PDF)
Solid state switches
Voltage stability
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