CTR-RIP
Ripple binary counter
Counts clock events through cascaded storage stages whose output changes do not occur simultaneously.
Schematic
IEC · RCTR
IEC ripple counter (RCTRm)
IEC counter marked RCTRm: an asynchronous ripple-carry counter with a cycle length of 2 to the power m.
In plain English
What does IEC ripple counter (RCTRm) mean?
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.
A simple 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.
What the drawings help you do
The symbol does not state the cumulative delay through the stages. That depends on the logic family and the number of bits.
This particular reference
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.
- Signal
- Electrical information passed between devices, rather than necessarily the main power supply.
- Schematic
- A drawing showing function and connections rather than physical appearance.
Read the source: Overview of IEEE Standard 91-1984: explanation of logic symbols (SDYZ001A) · SN74HC393 — ripple binary counters
IEC · Rectangular element with the RCTRm qualifier
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.
Shown as an independently authored educational illustration. Use the cited publication and drawing legend to verify the required drafting form.
Schematic · RCTR
What it represents
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.
How to read it
- RCTR warns that outputs settle in sequence.
- Avoid decoding multiple outputs without synchronisation.
Information to show or reference
- Use RCTR for asynchronous counters.
- Show the clear input and its polarity.
- Note any decoding that relies on stable outputs.
A distinction that matters
CTRm counters are synchronous and all outputs change on the same clock edge.
Sources you can follow
These public references support the explanation and provide further detail. Their graphics and downloadable files remain with their publishers.
Overview of IEEE Standard 91-1984: explanation of logic symbols (SDYZ001A)
Lists RCTRm as the asynchronous ripple-carry counter qualifier.
SN74HC393 — ripple binary counters
Ripple binary counter documentation.
About this graphic
This illustration was authored independently by Elora Grid to explain the concept. It is not reproduced from a customer drawing, an official standard graphic or a manufacturer CAD file. Its correspondence to an exact IEC or IEEE symbol identifier has not been certified.
SVG and DXF downloads contain this original artwork. DXF uses unscaled drawing units; a GA envelope supplies no product dimensions, clearances or fabrication information. Original artwork is available under CC BY 4.0. Third-party references retain their own terms.
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