NEG-OUT
IEC logic negation at output
Circle on an output edge meaning the internal 1 state of the element produces an external 0.
IEC
IEC · POL-OUT
IEC polarity indicator at output (active-low output)
Triangle on an output lead meaning the internal active state drives the output to a low level.
In plain English
What does IEC polarity indicator at output (active-low output) mean?
At an output, the polarity indicator triangle means the internal 1 state produces an external L level. It is the level-based counterpart of output negation and is used on device symbols for active-low interrupt, ready or fault outputs.
A simple example
When an active-low output drives an active-low input, the two triangles show directly that the signal is asserted low throughout, which avoids the double-negation reading needed with circles. This makes signal names with a low-active suffix line up with the graphic.
What the drawings help you do
The triangle does not state the output drive type. An active-low open-drain output also needs the open-circuit additional drawing mark inside the outline.
This particular reference
Triangle on an output lead meaning the internal active state drives the output to a low level. An output negation circle has the same meaning in positive logic but depends on the declared convention.
- Signal
- Electrical information passed between devices, rather than necessarily the main power supply.
- Schematic
- A drawing showing function and connections rather than physical appearance.
Read the source: Overview of IEEE Standard 91-1984: explanation of logic symbols (SDYZ001A)
IEC · Right-angled triangle on the output line next to the outline
Qualifying-symbol and dependency conventions as explained in TI's public overview of IEEE Std 91-1984, which incorporates IEC 617-12 work. Independent educational drawing; not certified IEC geometry or an IEC database identifier.
Shown as an independently authored educational illustration. Use the cited publication and drawing legend to verify the required drafting form.
Schematic · POL-OUT
What it represents
At an output, the polarity indicator triangle means the internal 1 state produces an external L level. It is the level-based counterpart of output negation and is used on device symbols for active-low interrupt, ready or fault outputs.
When an active-low output drives an active-low input, the two triangles show directly that the signal is asserted low throughout, which avoids the double-negation reading needed with circles. This makes signal names with a low-active suffix line up with the graphic.
The triangle does not state the output drive type. An active-low open-drain output also needs the open-circuit qualifier inside the outline.
How to read it
- Read the output as asserted when low.
- Check for an open-circuit qualifier as well.
Information to show or reference
- Draw the triangle on the output line at the outline edge.
- Name the net to show low-active sense.
- Add any output-type qualifier inside the outline.
A distinction that matters
An output negation circle has the same meaning in positive logic but depends on the declared convention.
Sources you can follow
These public references support the explanation and provide further detail. Their graphics and downloadable files remain with their publishers.
Overview of IEEE Standard 91-1984: explanation of logic symbols (SDYZ001A)
Polarity indicator at outputs.
About this graphic
This illustration was authored independently by Elora Grid to explain the concept. It is not reproduced from a customer drawing, an official standard graphic or a manufacturer CAD file. Its correspondence to an exact IEC or IEEE symbol identifier has not been certified.
SVG and DXF downloads contain this original artwork. DXF uses unscaled drawing units; a GA envelope supplies no product dimensions, clearances or fabrication information. Original artwork is available under CC BY 4.0. Third-party references retain their own terms.
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