{"schemaVersion":1,"slug":"iec-ripple-counter","name":"IEC ripple counter (RCTRm)","kind":"symbol","abbreviation":"RCTR","aliases":["asynchronous counter IEC form","ripple-carry counter","RCTR4"],"category":"logic-signals","drawingTypes":["Schematic"],"referenceFamilies":["IEC","Manufacturer"],"summary":"IEC counter marked RCTRm: an asynchronous ripple-carry counter with a cycle length of 2 to the power m.","description":["RCTRm identifies an asynchronous or ripple-carry counter of m bits. Each stage clocks the next, so outputs change one after another rather than simultaneously. The clock input carries a dynamic mark, and a clear input is usually shown as an asynchronous R.","Ripple counters are used where outputs are not decoded together at high speed, such as long frequency dividers or simple timers. Drawing them with RCTR rather than CTR warns a reviewer that decoding several outputs together may produce brief false states.","The symbol does not state the cumulative delay through the stages. That depends on the logic family and the number of bits."],"readingNotes":["RCTR warns that outputs settle in sequence.","Avoid decoding multiple outputs without synchronisation."],"drawingChecklist":["Use RCTR for asynchronous counters.","Show the clear input and its polarity.","Note any decoding that relies on stable outputs."],"distinction":"CTRm counters are synchronous and all outputs change on the same clock edge.","facts":[{"label":"Qualifier","value":"RCTRm"},{"label":"Timing","value":"Outputs change in sequence"},{"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":"Lists RCTRm as the asynchronous ripple-carry counter qualifier."},{"sourceId":"pub-electronics-ti-hc393","relevance":"Ripple binary counter documentation."}],"related":["ripple-binary-counter","iec-synchronous-binary-counter","iec-t-flip-flop"],"artwork":"s28-iec-ripple-counter","publishedOn":"2026-10-28","updatedOn":"2026-10-28","provenance":"independent-public-research","symbolVariant":{"convention":"IEC","form":"Rectangular element with the RCTRm qualifier","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. The counterpart is the matching functional concept; no equivalence of every detailed standard graphic is asserted.","counterpart":"ripple-binary-counter"},"plainEnglish":{"title":"What does IEC ripple counter (RCTRm) mean?","introduction":"RCTRm identifies an asynchronous or ripple-carry counter of m bits. Each stage clocks the next, so outputs change one after another rather than simultaneously. The clock input carries a dynamic mark, and a clear input is usually shown as an asynchronous R.","example":"Ripple counters are used where outputs are not decoded together at high speed, such as long frequency dividers or simple timers. Drawing them with RCTR rather than CTR warns a reviewer that decoding several outputs together may produce brief false states.","drawings":"The symbol does not state the cumulative delay through the stages. That depends on the logic family and the number of bits.","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"},{"label":"SN74HC393 — ripple binary counters","url":"https://www.ti.com/lit/ds/symlink/sn74hc393.pdf"}],"detail":"IEC counter marked RCTRm: an asynchronous ripple-carry counter with a cycle length of 2 to the power m. CTRm counters are synchronous and all outputs change on the same clock edge.","profileId":"reviewed-symbol-20261028"},"url":"https://eloragrid.ai/symbols/iec-ripple-counter","illustration":{"url":"https://eloragrid.ai/tools/electrical-library/illustrations/iec-ripple-counter.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":"Lists RCTRm as the asynchronous ripple-carry counter qualifier."},{"id":"pub-electronics-ti-hc393","title":"SN74HC393 — ripple binary counters","publisher":"Texas Instruments","url":"https://www.ti.com/lit/ds/symlink/sn74hc393.pdf","type":"manufacturer","scope":"Public device-function and terminal documentation used as an example of ripple binary counters. Example part numbers are manufacturer identifiers, not IEC/IEEE symbol IDs. Device ratings, pin numbering and availability remain in the selected product documentation.","checkedOn":"2026-10-14","reuse":"link-only","relevance":"Ripple binary counter documentation."}]}