{"schemaVersion":1,"slug":"iec-active-low-input-indicator","name":"IEC polarity indicator at input (active-low input)","kind":"symbol","abbreviation":"POL-IN","aliases":["input polarity triangle","active-low input mark","polarity indicator input"],"category":"logic-signals","drawingTypes":["Schematic"],"referenceFamilies":["IEC","Manufacturer"],"summary":"Small triangle on an input lead meaning a low level produces the internal active state.","description":["The polarity indicator is a small right-angled triangle drawn on the input line where it meets the outline. It states that the L level produces the internal 1 state. Because it refers directly to levels, it does not need a positive or negative logic declaration, which is why device data books favour it.","On drawings that combine device-level schematics with functional logic, the polarity triangle tells the reader that a pin is active low, such as an enable, chip-select or reset input. In positive logic it means the same as a negation circle.","The triangle does not indicate an internal pull-up or default state for an unconnected input. Those details are device data."],"readingNotes":["Read the triangle as active when low.","Equivalent to a negation circle only in positive logic."],"drawingChecklist":["Draw the triangle on the outside of the outline, pointing in the signal direction.","Use it consistently in place of circles on level-based schematics.","Name active-low nets with a consistent suffix or overbar."],"distinction":"The negation circle is a logic statement that needs a declared convention; the triangle is a level statement.","facts":[{"label":"Meaning","value":"L level produces internal 1"},{"label":"Equivalent in positive logic","value":"Input negation circle"},{"label":"Artwork scope","value":"Original educational illustration; consult the applicable standard and the selected device documentation for the exact graphic"}],"references":[{"sourceId":"s28-ti-ieee91-logic-symbols","relevance":"Explains the logic polarity indicator and why data books use it."}],"related":["iec-logic-input-negation","iec-active-low-output-indicator","iec-enable-input"],"artwork":"s28-iec-active-low-input-indicator","publishedOn":"2026-10-28","updatedOn":"2026-10-28","provenance":"independent-public-research","symbolVariant":{"convention":"IEC","form":"Right-angled triangle on the input line next to the outline","reference":"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."},"plainEnglish":{"title":"What does IEC polarity indicator at input (active-low input) mean?","introduction":"The polarity indicator is a small right-angled triangle drawn on the input line where it meets the outline. It states that the L level produces the internal 1 state. Because it refers directly to levels, it does not need a positive or negative logic declaration, which is why device data books favour it.","example":"On drawings that combine device-level schematics with functional logic, the polarity triangle tells the reader that a pin is active low, such as an enable, chip-select or reset input. In positive logic it means the same as a negation circle.","drawings":"The triangle does not indicate an internal pull-up or default state for an unconnected input. Those details are device data.","terms":[{"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":"Overview of IEEE Standard 91-1984: explanation of logic symbols (SDYZ001A)","url":"https://www.ti.com/lit/ml/sdyz001a/sdyz001a.pdf"}],"detail":"Small triangle on an input lead meaning a low level produces the internal active state. The negation circle is a logic statement that needs a declared convention; the triangle is a level statement.","profileId":"reviewed-symbol-20261028"},"url":"https://eloragrid.ai/symbols/iec-active-low-input-indicator","illustration":{"url":"https://eloragrid.ai/tools/electrical-library/illustrations/iec-active-low-input-indicator.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-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":"Explains the logic polarity indicator and why data books use it."}]}