Electronic – Different Zener Diode Symbols

diodessymbol [~]zener

In the past I have seen two different symbols for a zener diode. One shows the complete "Z" shape on the cathode, and one shows more of an "L" shape on the cathode (see images below):

enter image description here

What is the difference between these? Do they actually have different meanings, or are they two ways of showing the same thing? Perhaps one is European and one is American? I always thought that they were simply two ways of showing the same thing, but a coworker of mine questioned it and now I am looking for confirmation.

Best Answer

The base symbol I can fine no definite standard reference for. I'd guess the majority of us would use it.


simulate this circuit – Schematic created using CircuitLab

Graphical samples for the Australian Standard AS 1102 (1989) Graphical symbols for electrotechnical does appear to reference this symbol. I don't have a copy, so I cannot confirm this.

Europe: International Electrotechnical Commission IEC60617 (2012) Graphical Symbols for Diagrams provide the following:

Zener Diode - IEC60617

with the IEC60617 (1996) version defining the bars. Diode Bars for:

  • Schottky
  • Tunnel
  • Zener
  • Bi-directional
  • Unitunnel

Their usage of straight bars (05-02-04) is for Bi-directional or breakdown diode.

Bi-directional or breakdown diode

US: IEEE 315 (1975) Standard for Graphic Symbols for Electrical and Electronics Diagrams provides the straight bar symbol:

Zener - IEEE 315

ANSI Y32.2 (1975) Graphic Symbols for Electrical and Electronics Diagrams has been superseded by IEEE315. It references the same symbol as IEEE315.