Thyristors Provide Enhanced Surge Protection

Littelfuse’s two SIDACtor series of protection thyristors are optimized to protect equipment located in high exposure environments from severe overvoltage transients. The Pxxx0MEL 5kA Series and Pxxx0FNL 3kA Series SIDACtor protection thyristors offer enhanced reliability through multiple high energy surge events. Unlike many non-semiconductor-based high power protective products, which can experience functional degradation after only a few surge events, the Pxxx0MEL and Pxxx0FNL Series are semiconductor-based components, and will continue to provide protection through multiple surge events without functional degradation.


Typical applications for Pxxx0MEL 5kA Series and Pxxx0FNL 3kA Series SIDACtor protection thyristors include:

  • CATV amplifiers.
  • Telecom base station equipment.
  • Cell towers.
  • UPS/AC high-power distribution grids.
  • Automotive battery charging systems.
  • Solar power system DC/AC inverters.
  • Uninterruptible battery backup systems.  

Pxxx0MEL Series and Pxxx0FNL Series SIDACtor protection thyristors offer these key benefits:

  • Clamping that is superior to traditional MOV passive technology for AC line protection provides high-power surge protection up to 3kA or 5kA.
  • Low on-state voltage condition ensures low thermal accumulation during long-term events.
  • Unlike gas discharge tubes (GDTs) or surge arrestors, these semiconductor crowbar devices have no wear-out mechanism, so they can withstand multiple surge events with minimal degradation, eliminating the need to dispatch service personnel to replace damaged equipment.  

Additional information is available on the Pxxx0MEL 5kA Series SIDACtor product page and the Pxxx0FNL 3kA Series SIDACtor product page.