P4802ACMC datasheet(165/212 Pages) TECCOR

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Construction and Operation

5 - 3

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SIDACtor® Data Book and Design Guide

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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 VDRM, IDRM, VS, IH, and VT, as shown in Figure 5.1.

VDRM 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. IDRM is the maximum value of leakage

current that results from the application of VDRM. Switching voltage (VS) is the maximum

voltage that subsequent components may be subjected to during a fast-rising (100 V/µs)

overvoltage condition. Holding current (IH) is the minimum current required to maintain the

device in the on state. On-state voltage (VT) 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 (IDRM) less than 5 µA, making it invisible to the circuit it is protecting. As a

transient voltage exceeds the SIDACtor device’s VDRM, the device begins to enter its

protective mode with characteristics similar to an avalanche diode. When supplied with

enough current (IS), 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

IDRM

VDRM

-V

-I

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