I've seen power protection that uses:

  • MOV (metal-oxide varistor)
  • Inductor
  • TVS diode

Application Note: Transient Voltage Suppressors (TVS Diode) Applications Overview

enter image description here I didn't see any design guide for the inductor selection I choose 1 A inductor 4.7 µH, but doesn't that mean it will carry the surge current that TVS should clamp?

enter image description here enter image description here

I'm not sure is 4.7 µH the right selection or not.

  • \$\begingroup\$ I do not see any reason for placing an inductor between the protective elements. If used, it should be placed after the TVS diode so that the diode can do it’s job. \$\endgroup\$ – Stefan Wyss Oct 8 '18 at 19:30
  • \$\begingroup\$ the first picture is not mine, as much as i understand, the inductor is there to delay surge current from TVS diode so the varistor takes most of the power of that surge. i dont know if its effective or not that what comes in my mind \$\endgroup\$ – Hasan alattar Oct 9 '18 at 5:53
  • \$\begingroup\$ Why don’t you simulate it? \$\endgroup\$ – winny Oct 9 '18 at 6:11
  • \$\begingroup\$ i've never used simulation, only the one altium provide for very simple circuits RC, LC, filters that already have spice model by default. \$\endgroup\$ – Hasan alattar Oct 9 '18 at 6:52
  • \$\begingroup\$ i did use LT spice today, it just doesnt give what i should do, good to see that 8kV voltage gets shunted by the varistor and zener diode but it need much more study of spice simulation i guess to simulate the real component and i guess current and voltage should be measured \$\endgroup\$ – Hasan alattar Oct 9 '18 at 8:54

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