{"schemaVersion":1,"slug":"iec-synchronous-binary-counter","name":"IEC synchronous binary counter (CTRm)","kind":"symbol","abbreviation":"CTR4","aliases":["CTR4 counter","IEC 4-bit counter","synchronous counter IEC form"],"category":"logic-signals","drawingTypes":["Schematic"],"referenceFamilies":["IEC","Manufacturer"],"summary":"IEC counter marked CTRm, where m is the bit count and the cycle length is 2 to the power m.","description":["The general qualifier CTRm identifies a counter with m bits and a cycle length of 2 to the power m. In IEC form the clock appears as C with a + to show counting up, and load, clear and enable inputs use dependency notation such as M1 for load mode and G for count enable. Outputs carry binary weights 1, 2, 4 and 8.","A reader should identify the synchronous and asynchronous inputs from their prefixes, then find the carry output, often labelled CT=15, used to cascade stages. On control drawings counters represent event totals, batch counts or divide-by-n timing.","The symbol does not state maximum count rate or whether the clear is synchronous, except through dependency labels. Read the prefixes carefully."],"readingNotes":["CTRm gives the bit count; the cycle is 2 to the power m.","CT=15 marks the terminal-count output used for cascading."],"drawingChecklist":["State the bit count in the qualifier.","Label load, clear and enable with dependency notation.","Show cascade connections between stages."],"distinction":"CTR DIVm states the cycle length directly and is used for non-binary counters such as decade counters.","facts":[{"label":"Qualifier","value":"CTRm"},{"label":"Cycle length","value":"2 to the power m"},{"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 CTRm and related counter qualifiers and the contents output CT=."},{"sourceId":"pub-electronics-ti-hc163","relevance":"Synchronous binary counter documentation."}],"related":["synchronous-binary-counter","iec-decade-counter","iec-ripple-counter"],"artwork":"s28-iec-synchronous-binary-counter","publishedOn":"2026-10-28","updatedOn":"2026-10-28","provenance":"independent-public-research","symbolVariant":{"convention":"IEC","form":"Rectangular element with CTRm qualifier, common-control block and weighted outputs","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":"synchronous-binary-counter"},"plainEnglish":{"title":"What does IEC synchronous binary counter (CTRm) mean?","introduction":"The general additional drawing mark CTRm identifies a counter with m bits and a cycle length of 2 to the power m. In IEC form the clock appears as C with a + to show counting up, and load, clear and enable inputs use dependency notation such as M1 for load mode and G for count enable. Outputs carry binary weights 1, 2, 4 and 8.","example":"A reader should identify the synchronous and asynchronous inputs from their prefixes, then find the carry output, often labelled CT=15, used to cascade stages. On control drawings counters represent event totals, batch counts or divide-by-n timing.","drawings":"The symbol does not state maximum count rate or whether the clear is synchronous, except through dependency labels. Read the prefixes carefully.","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":"SN74HC163 — synchronous binary counters","url":"https://www.ti.com/lit/ds/symlink/sn74hc163.pdf"}],"detail":"IEC counter marked CTRm, where m is the bit count and the cycle length is 2 to the power m. CTR DIVm states the cycle length directly and is used for non-binary counters such as decade counters.","profileId":"reviewed-symbol-20261028"},"url":"https://eloragrid.ai/symbols/iec-synchronous-binary-counter","illustration":{"url":"https://eloragrid.ai/tools/electrical-library/illustrations/iec-synchronous-binary-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 CTRm and related counter qualifiers and the contents output CT=."},{"id":"pub-electronics-ti-hc163","title":"SN74HC163 — synchronous binary counters","publisher":"Texas Instruments","url":"https://www.ti.com/lit/ds/symlink/sn74hc163.pdf","type":"manufacturer","scope":"Public device-function and terminal documentation used as an example of synchronous 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":"Synchronous binary counter documentation."}]}