I'm working on an electronics project and decided I need (among other things) an ESD diode to protect my inputs. I selected a diode which should do the trick: https://www.digikey.ca/product-detail/en/vishay-semiconductor-diodes-division/GSOT05C-E3-08/GSOT05C-E3-08CT-ND/1680616

I was going to use this for everything: signal input, Vcc, etc. Looking farther down the Digi-Key page, though, it says: Power Line Protection: No.

The data sheet says the diode can protect "two signal or data lines," and does not claim it will not work on a supply. I see no reason why I can't use the same diode on a 5V Vcc net if I'd use it on a 5V logic net, so what's up with this bizarre "power line protection" stuff? I searched high and low for app notes, etc., but didn't come up with anything.

Any insight into this will be appreciated. If there isn't a satisfactory answer, I'll go ahead and use this "signal/data" diode on my power nets!


1 Answer 1


You're right that this does not appear to be a standard term. From looking at the differences between TVS diodes on Digi-Key with and without it, though, I think it has a fairly simple meaning. First, it only applies to the steering configuration; you're using zener diodes, so you don't have to care about it at all.

Within the steering configuration, there are two approaches: you can connect the upper diode to your power rail, like on the left:


simulate this circuit – Schematic created using CircuitLab

This has the disadvantage that any positive ESD strikes get shunted into the power rail, which can raise it to a voltage above its rating. Therefore, the configuration on the right is often used, with a zener diode instead of (or in addition to) the connection to the power rail, thus protecting the power rail from overvoltage: "Power Line Protection".

(If you're wondering why someone would use this latter configuration rather than only a zener diode, it allows several signals to be protected with mostly regular diodes: only one zener.)

  • \$\begingroup\$ Thanks for your insight -- that takes the mystery out of it. I'll go ahead and use those zener diodes wherever they're necessary. \$\endgroup\$
    – int32_t
    Apr 13, 2017 at 4:06

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