# IEC polarity indicator at output (active-low output)

Canonical URL: https://eloragrid.ai/symbols/iec-active-low-output-indicator
Publisher: Elora Grid
Updated: 2026-10-28
Lookup label: POL-OUT
Drawing use: Schematic
Reference families: IEC, Manufacturer

## Symbol convention

Convention: IEC
Form: 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.

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.

### Terms

- Signal: Electrical information passed between devices, rather than necessarily the main power supply.
- Schematic: A drawing showing function and connections rather than physical appearance.

Concept diagram: Identify the device and form → Read the connections and state → Check the equipment reference
A guide to reading this reference. The original symbol illustration and its drawing notes appear below; these boxes are not a wiring diagram.

- [Overview of IEEE Standard 91-1984: explanation of logic symbols (SDYZ001A)](https://www.ti.com/lit/ml/sdyz001a/sdyz001a.pdf)


## 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.

## Important distinction

An output negation circle has the same meaning in positive logic but depends on the declared convention.

## Facts

- Meaning: Internal 1 produces L level
- Typical pins: Interrupt, fault, ready outputs
- Artwork scope: Original educational illustration; consult the applicable standard and the selected device documentation for the exact graphic

## Public references

- [Overview of IEEE Standard 91-1984: explanation of logic symbols (SDYZ001A)](https://www.ti.com/lit/ml/sdyz001a/sdyz001a.pdf) — Texas Instruments. Polarity indicator at outputs.

## Graphic scope

Independent original educational concept illustration by Elora Grid. Not a certified standards graphic or manufacturer footprint. Unitless; not to scale. Original artwork licence: https://creativecommons.org/licenses/by/4.0/. Publisher material is linked only.