# ANSI three-input OR gate

Canonical URL: https://eloragrid.ai/symbols/ansi-three-input-or-gate
Publisher: Elora Grid
Updated: 2026-10-28
Lookup label: OR3
Drawing use: Schematic
Reference families: IEEE / ANSI, Manufacturer

## Symbol convention

Convention: IEEE / ANSI
Form: Curved-back OR outline with three inputs
Distinctive-shape form as used in IEEE/ANSI-style schematics and manufacturer data books. Independent educational drawing; exact standard geometry and compliance are not asserted. The counterpart is the matching functional concept; no equivalence of every detailed standard graphic is asserted.
Related representation: [OR gate](https://eloragrid.ai/symbols/logic-or-gate)

Curved-back OR outline with three inputs; any one high input drives the output high.

## In plain English

### What does ANSI three-input OR gate mean?

The three-input OR uses the shield-shaped outline with a concave back and a pointed front, with a third input added on the curved back edge. Any input at logic 1 produces a logic 1 output. Triple three-input OR packages exist for this function.

### A simple example

Typical uses include combining several fault or request signals into a single command. The inputs should be identified by signal name so that a test engineer can trace which source produced the output when the logic operates.

### What the drawings help you do

The outline does not tell the reader whether inputs are filtered or latched. Any such behaviour must appear as separate elements before or after the gate.

### This particular reference

Curved-back OR outline with three inputs; any one high input drives the output high. An exclusive-OR has an extra curved line behind the back; a plain OR has a single back curve.

### 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.

- [CDx4HC4075 triple 3-input OR gates](https://www.ti.com/lit/ds/symlink/cd74hc4075.pdf)


## What it represents

The three-input OR uses the shield-shaped outline with a concave back and a pointed front, with a third input added on the curved back edge. Any input at logic 1 produces a logic 1 output. Triple three-input OR packages exist for this function.
Typical uses include combining several fault or request signals into a single command. The inputs should be identified by signal name so that a test engineer can trace which source produced the output when the logic operates.
The outline does not tell the reader whether inputs are filtered or latched. Any such behaviour must appear as separate elements before or after the gate.

## How to read it

- Inputs meet the curved back, not a straight edge.
- Trace each input to its source tag.

## Information to show or reference

- Terminate input leads on the concave back.
- Label each input signal.
- Show unused-input tie-offs for multi-input parts.

## Important distinction

An exclusive-OR has an extra curved line behind the back; a plain OR has a single back curve.

## Facts

- Inputs: Three
- Example device family: Triple three-input OR packages
- Artwork scope: Original educational illustration; consult the applicable standard and the selected device documentation for the exact graphic

## Public references

- [CDx4HC4075 triple 3-input OR gates](https://www.ti.com/lit/ds/symlink/cd74hc4075.pdf) — Texas Instruments. Manufacturer documentation for triple three-input OR gates.

## 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.