Protection Thyristor utilizes silicon crowbar technology.

Press Release Summary:

Housed in SOT23-6 package, SDP Series SIDACtor® Protection Thyristor delivers overvoltage protection for broadband/xDSL telecommunications equipment with minimal effect on connection speed and reach. Unit provides crowbar response to surge events with max threshold of 29 V at 250 V/µs, and offers surge protection up to 30 A while maintaining low off-state capacitance. By responding quickly to surges, device prevents damage caused by coupling of transient events across small signal transformer.

Original Press Release:

New Littelfuse SIDACtor® Protection Thyristor Provides 45 Percent Lower Capacitance than Clamping Devices

Offers industry-leading AC protection for broadband telecom equipment

CHICAGO, — Littelfuse, Inc., the global leader in circuit protection, has introduced an ultra-low capacitance protection thyristor. The SDP Series SIDACtor® Protection Thyristor in the SOT23-6 package provides robust overvoltage protection for broadband/xDSL telecommunications equipment with minimal effects on connection speed and reach. Patent-pending silicon crowbar technology allows for 45 percent lower capacitance than clamping devices like transient voltage suppressor (TVS) diodes. It also provides faster response to surges, ensuring lower overshoot voltages and improved electrostatic discharge (ESD), lightning and power fault protection. It is designed for the tertiary or line driver side protection position in VDSL2, ADSL2, ADSL2+ telecommunications applications and general I/O protection functions. Its small-footprint package is well-suited for high density card designs.

Crowbar devices operate as shunt devices in response to a surge that exceeds the breakover voltage. After switching on, they offer a very low impedance path that diverts transient energy away from the load. In contrast, clamping devices limit the transient voltage to a set value. When the applied voltage reaches the device’s breakdown value, it switches to a much lower resistance value to minimize the transient energy the circuit will experience.

“The SDP Series SOT23-6 is the lowest off-state capacitance crowbarring component on the market and provides the industry’s quickest surge suppression response,” said Betty Li, Global Product Manager for the SIDACtor Protection Thyristor product line. “It allows circuit designers to provide much faster suppression response to surges than clamping devices while maintaining signal integrity.”


Helps prevent xDSL driver chip failures by providing a crowbar response to surge events with a maximum threshold of 29V at 250V/µs

Provides robust surge protection performance up to 30A while maintaining low off-state capacitance for better AC protection

Responds quickly to surges, preventing damage caused by the coupling of transient events across the small signal transformer


SDP SOT23-6 SIDACtor Protection Thyristors are available on reels in quantities of 3,000. Samples are available now for bulk orders; sample requests can be placed through authorized Littelfuse distributors worldwide. For a listing of Littelfuse distributors, please visit

For More Information

Additional information is available on the SDP SOT23-6 product page and datasheet. If you have technical questions, please contact: Betty Li, Global Product Manager, SIDACtor Protection Thyristors,

About Littelfuse

Founded in 1927, Littelfuse is the world leader in circuit protection with growing global platforms in power control and sensing. The company serves global customers in the electronics, automotive and industrial markets with technologies including fuses, semiconductors, polymers, ceramics, relays and sensors. Littelfuse has over 7,000 employees in more than 35 locations throughout the Americas, Europe and Asia. For more information, please visit the Littelfuse website:

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