Cross Reference
Protection

TSS (Thyristor Surge Suppressor)

Crowbar-style surge protectors for telecom and high-energy line protection.

What is it?

A TSS (Thyristor Surge Suppressor, sometimes called SIDACtor or surge thyristor) is a PNPN structure that, when triggered by an over-voltage event, snaps into a low-impedance crowbar state. Unlike a TVS that clamps to a fixed clamping voltage, a TSS pulls down to ~3 V holding voltage and shunts very high currents (tens to hundreds of amps) with minimal heating. Used where the surge energy is too high for a clamping TVS to absorb.

TSS crowbar versus TVS clampVt →TVS: clamps at VCTSS: crowbar to ~3 Vnormalfault currenttrigger
A TVS holds at its clamping voltage VC during a surge. A TSS, once triggered, snaps to a low holding voltage (~3 V) and conducts almost all the surge current, far less power dissipated in the device itself.

When do you need it?

  • Telecom subscriber-line interfaces (POTS, xDSL, ISDN) facing lightning-induced surges.
  • Industrial Ethernet (10/100/1G) with long outdoor cable runs.
  • Power-line communication interfaces.
  • Any system that must survive multi-kA surges per ITU-T K.20 / K.21 / GR-1089.

How to pick the right one

VBR (Breakdown Voltage)
Above maximum normal line voltage. Telecom POTS uses ~190-265 V (high-voltage TSS).
IH (Holding Current)
Below the maximum normal line current. Otherwise the TSS won't reset after triggering.
ITSP (Peak Pulse Surge Current)
Must exceed the lightning surge rating you need to pass, typically 100 A to 1 kA for telecom.
Symmetric vs Asymmetric
Telecom POTS uses symmetric (line swings positive and negative); some industrial uses asymmetric.

What Magnias offers

Magnias TSS and SIDAC parts cover VDRM from 6 V to 750 V in SOD123-FL, SMB, DFN3333-2L and SOP-8: CPxxxxCB (SMB) and TSPxxxxM-D1 / TSPxxxxB-D1 (SOD123-FL) for telecom, Ethernet and industrial lines, the 600 V / 750 V TSPxx00CJ SIDACs (SMB), the programmable protectors TSP61089S / TSP61089L (SOP-8) and TSP4200E-Q32 (DFN3333-2L) for FXS and PBX ports, and SKxxxJ-D1 SIDACs for lamp and gas ignitors.

Common questions

How is TSS different from a TVS?
A TVS clamps (acts like a Zener). A TSS crowbars (snaps to a low-voltage held state). TSS handles much higher surge energy because almost no power is dissipated in the device once it triggers.
Will a TSS work for ESD protection?
Partly. Many Magnias TSS parts switch in nanoseconds and carry IEC 61000-4-2 ratings up to ±30 kV, so they survive ESD on the line. But their breakover voltage is above what most IC pins can take, so on sensitive pins pair the TSS with a low-capacitance ESD diode or TVS closer to the IC.
Why does TSS need to reset?
After triggering, the TSS holds in low-Z state while load current exceeds IH. When normal line current drops below IH (e.g., on the next ring cycle for telecom), the TSS resets. You need to verify IH is below your minimum normal current.
Related FAQs
Protection

ESD Protection Diodes

Tiny diodes that protect your IC pins from human-body static and other transient events.

 Protection

TVS Diodes (General)

Workhorse transient voltage suppressors for power rails and lower-speed signal lines.

 Protection

Load Dump TVS (DO-218)

Heavy-duty TVS purpose-built for automotive 12 V / 24 V load-dump surge events.

 Protection

Short-to-VBUS Protection

Protection ICs that keep USB Type-C CC and SBU pins safe when they are shorted to VBUS.
← Previous Common-Mode Filter + ESD (CMF+ESD) All categories Next → ePoly (Polymer ESD Suppressor)