Construction and Operation
2002 Teccor Electronics
SIDACtor
Data Book and Design Guide
5 - 3
http://www.teccor.com
+1 972-580-7777
T
Construction and Operation
SIDACtor
devices are thyristor devices used to protect sensitive circuits from electrical
disturbances caused by lightning-induced surges, inductive-coupled spikes, and AC power
cross conditions. The unique structure and characteristics of the thyristor are used to create
an overvoltage protection device with precise and repeatable turn-on characteristics with
low voltage overshoot and high surge current capabilities.
Key Parameters
Key parameters for
SIDACtor
devices are V
DRM
, I
DRM
, V
S
, I
H
, and V
T
, as shown in Figure 5.1.
V
DRM
is the repetitive peak off-state voltage rating of the device (also known as stand-off
voltage) and is the continuous peak combination of AC and DC voltage that may be applied
to the
SIDACtor
device in its off-state condition. I
DRM
is the maximum value of leakage
current that results from the application of V
DRM
. Switching voltage (V
S
) is the maximum
voltage that subsequent components may be subjected to during a fast-rising (100 V/μs)
overvoltage condition. Holding current (I
H
) is the minimum current required to maintain the
device in the on state. On-state voltage (V
T
) is the maximum voltage across the device
during full conduction.
Figure 5.1
V-I Characteristics
Operation
The
SIDACtor
device operates much like a switch. In the off state, the device exhibits
leakage currents (I
DRM
) less than 5 μA, making it invisible to the circuit it is protecting. As a
transient voltage exceeds the
SIDACtor
device’s V
DRM
, the device begins to enter its
protective mode with characteristics similar to an avalanche diode. When supplied with
enough current (I
S
), the
SIDACtor
device switches to an on state, shunting the surge from
the circuit it is protecting. While in the on state, the
SIDACtor
device is able to sink large
I
H
I
T
I
S
I
DRM
V
DRM
V
T
+V
-V
+I
-I
V
S