{"schemaVersion":1,"slug":"ansi-three-input-nor-gate","name":"ANSI three-input NOR gate","kind":"symbol","abbreviation":"NOR3","aliases":["3-input NOR gate","triple-input NOR","distinctive-shape NOR3"],"category":"logic-signals","drawingTypes":["Schematic"],"referenceFamilies":["IEEE / ANSI","Manufacturer"],"summary":"Three-input OR outline with an output bubble; the output is high only when all three inputs are low.","description":["The three-input NOR gate is the OR outline with three inputs and a bubble at the pointed output. The output is high only when all inputs are low. Triple three-input NOR packages provide the function and it is often used to create an all-clear signal.","When all inputs are themselves active-low alarm lines, the same function may be easier to read as an AND outline with bubbled inputs. A consistent choice across the drawing set makes reviews quicker.","The symbol does not show output drive strength or whether the output may be wired to others. Check the device type before connecting outputs together."],"readingNotes":["Look for the output bubble at the point of the outline.","Check whether a De Morgan form is used elsewhere for the same signal."],"drawingChecklist":["Show the output bubble clearly.","Name the condition each input represents.","Note the device section and pin numbers."],"distinction":"An AND outline with three bubbled inputs is the De Morgan equivalent of this gate.","facts":[{"label":"Inputs","value":"Three"},{"label":"Output high when","value":"All inputs low"},{"label":"Artwork scope","value":"Original educational illustration; consult the applicable standard and the selected device documentation for the exact graphic"}],"references":[{"sourceId":"s28-ti-hc27","relevance":"Manufacturer documentation for triple three-input NOR gates."}],"related":["logic-nor-gate","ansi-nor-as-negative-and-gate","iec-nor-gate"],"artwork":"s28-ansi-three-input-nor-gate","publishedOn":"2026-10-28","updatedOn":"2026-10-28","provenance":"independent-public-research","symbolVariant":{"convention":"IEEE / ANSI","form":"OR outline with three inputs and an output bubble","reference":"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.","counterpart":"logic-nor-gate"},"plainEnglish":{"title":"What does ANSI three-input NOR gate mean?","introduction":"The three-input NOR gate is the OR outline with three inputs and a bubble at the pointed output. The output is high only when all inputs are low. Triple three-input NOR packages provide the function and it is often used to create an all-clear signal.","example":"When all inputs are themselves active-low alarm lines, the same function may be easier to read as an AND outline with bubbled inputs. A consistent choice across the drawing set makes reviews quicker.","drawings":"The symbol does not show output drive strength or whether the output may be wired to others. Check the device type before connecting outputs together.","terms":[{"name":"Terminal","meaning":"An identified point where a conductor connects."},{"name":"Signal","meaning":"Electrical information passed between devices, rather than necessarily the main power supply."},{"name":"Schematic","meaning":"A drawing showing function and connections rather than physical appearance."}],"diagram":"flow","steps":["Identify the device and form","Read the connections and state","Check the equipment reference"],"caption":"A guide to reading this reference. The original symbol illustration and its drawing notes appear below; these boxes are not a wiring diagram.","sources":[{"label":"SNx4HC27 triple 3-input NOR gates","url":"https://www.ti.com/lit/ds/symlink/sn74hc27.pdf"}],"detail":"Three-input OR outline with an output bubble; the output is high only when all three inputs are low. An AND outline with three bubbled inputs is the De Morgan equivalent of this gate.","profileId":"reviewed-symbol-20261028"},"url":"https://eloragrid.ai/symbols/ansi-three-input-nor-gate","illustration":{"url":"https://eloragrid.ai/tools/electrical-library/illustrations/ansi-three-input-nor-gate.svg","scope":"Original educational concept; not an official standard graphic or product footprint","license":"https://creativecommons.org/licenses/by/4.0/"},"sources":[{"id":"s28-ti-hc27","title":"SNx4HC27 triple 3-input NOR gates","publisher":"Texas Instruments","url":"https://www.ti.com/lit/ds/symlink/sn74hc27.pdf","type":"manufacturer","scope":"Device documentation for three-input NOR gates.","checkedOn":"2026-10-28","reuse":"link-only","relevance":"Manufacturer documentation for triple three-input NOR gates."}]}