{"schemaVersion":1,"slug":"ansi-open-collector-inverter","name":"ANSI open-collector inverter","kind":"symbol","abbreviation":"OC-NOT","aliases":["open-drain inverter","inverter with open-collector output","open-collector NOT gate"],"category":"logic-signals","drawingTypes":["Schematic"],"referenceFamilies":["IEEE / ANSI","Manufacturer"],"summary":"Inverter triangle with output bubble and an open-circuit mark, needing an external pull-up to produce a high level.","description":["This is an inverter whose output transistor can only pull low. On distinctive-shape schematics the triangle and bubble are retained and an open-collector or open-drain mark, often the underlined diamond, is placed inside or beside the outline. A pull-up resistor or load to a supply completes the circuit.","Open-drain inverters are used to drive indicator LEDs, relay inputs and shared interrupt or alarm lines, and to translate to a higher pull-up voltage within the device rating. The schematic should show the pull-up value and its supply rail next to the gate.","The output state with no pull-up is undefined when the transistor is off. A drawing that omits the pull-up is incomplete even though the gate symbol is correct."],"readingNotes":["Find the pull-up or load; without it the high level is undefined.","Check whether the output is shared with other open-collector outputs."],"drawingChecklist":["Mark the open-collector or open-drain output.","Show the pull-up and its supply.","Record the maximum output voltage and sink current from the datasheet."],"distinction":"The non-inverting open-collector buffer has no output bubble.","facts":[{"label":"Output stage","value":"Open collector or open drain"},{"label":"External part","value":"Pull-up resistor or load"},{"label":"Artwork scope","value":"Original educational illustration; consult the applicable standard and the selected device documentation for the exact graphic"}],"references":[{"sourceId":"s28-ti-hc05","relevance":"Manufacturer documentation for inverters with open-drain outputs."},{"sourceId":"s28-ti-ieee91-logic-symbols","relevance":"Open-collector output qualifier."}],"related":["open-collector-buffer","ansi-wired-and-connection","logic-inverter"],"artwork":"s28-ansi-open-collector-inverter","publishedOn":"2026-10-28","updatedOn":"2026-10-28","provenance":"independent-public-research","symbolVariant":{"convention":"IEEE / ANSI","form":"Inverter triangle with bubble and open-circuit output marking","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."},"plainEnglish":{"title":"What does ANSI open-collector inverter mean?","introduction":"This is an inverter whose output transistor can only pull low. On distinctive-shape schematics the triangle and bubble are retained and an open-collector or open-drain mark, often the underlined diamond, is placed inside or beside the outline. A pull-up resistor or load to a supply completes the circuit.","example":"Open-drain inverters are used to drive indicator LEDs, relay inputs and shared interrupt or alarm lines, and to translate to a higher pull-up voltage within the device rating. The schematic should show the pull-up value and its supply rail next to the gate.","drawings":"The output state with no pull-up is undefined when the transistor is off. A drawing that omits the pull-up is incomplete even though the gate symbol is correct.","terms":[{"name":"Normally open / normally closed","meaning":"The contact state in the normal condition defined for the drawing."},{"name":"Coil","meaning":"A wound conductor that can produce a magnetic field when energised."},{"name":"Signal","meaning":"Electrical information passed between devices, rather than necessarily the main power supply."}],"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":"SNx4HC05 hex inverters with open-drain outputs","url":"https://www.ti.com/lit/ds/symlink/sn74hc05.pdf"},{"label":"Overview of IEEE Standard 91-1984: explanation of logic symbols (SDYZ001A)","url":"https://www.ti.com/lit/ml/sdyz001a/sdyz001a.pdf"}],"detail":"Inverter triangle with output bubble and an open-circuit mark, needing an external pull-up to produce a high level. The non-inverting open-collector buffer has no output bubble.","profileId":"reviewed-symbol-20261028"},"url":"https://eloragrid.ai/symbols/ansi-open-collector-inverter","illustration":{"url":"https://eloragrid.ai/tools/electrical-library/illustrations/ansi-open-collector-inverter.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-hc05","title":"SNx4HC05 hex inverters with open-drain outputs","publisher":"Texas Instruments","url":"https://www.ti.com/lit/ds/symlink/sn74hc05.pdf","type":"manufacturer","scope":"Device documentation for inverters with open-drain outputs.","checkedOn":"2026-10-28","reuse":"link-only","relevance":"Manufacturer documentation for inverters with open-drain outputs."},{"id":"s28-ti-ieee91-logic-symbols","title":"Overview of IEEE Standard 91-1984: explanation of logic symbols (SDYZ001A)","publisher":"Texas Instruments","url":"https://www.ti.com/lit/ml/sdyz001a/sdyz001a.pdf","type":"manufacturer","scope":"Public explanation of rectangular logic symbols, general qualifiers, input and output qualifiers, dependency notation, bistable elements and coders, consistent with IEC 617-12 work.","checkedOn":"2026-10-28","reuse":"link-only","relevance":"Open-collector output qualifier."}]}