Vm
IEC OR dependency (V)
Dependency label Vm: affected terminals are ORed with the V input, forced to 1 when V is active.
IEC
IEC · Nm
IEC negate dependency (N)
Dependency label Nm: when the N input is active, affected terminals are complemented.
In plain English
What does IEC negate dependency (N) mean?
N dependency is the negate or exclusive-OR relationship. When the Nm affecting input is at its internal 1 state, each affected input or output labelled m is complemented. At 0 it has no effect. The result is a controllable inverter folded into the device symbol.
A simple example
This notation appears on devices with selectable output polarity, such as programmable inverting or non-inverting buffers. Reading the N label tells the drafter that the same pin can produce either sense depending on the control input.
What the drawings help you do
The label does not indicate when the polarity may be changed during operation. That is a matter of device timing and system design.
This particular reference
Dependency label Nm: when the N input is active, affected terminals are complemented. Fixed output negation is a circle or triangle; N dependency makes the negation switchable.
- Normally open / normally closed
- The contact state in the normal condition defined for the drawing.
- 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)
IEC · Affecting input labelled Nm with affected terminals labelled m
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.
Shown as an independently authored educational illustration. Use the cited publication and drawing legend to verify the required drafting form.
Schematic · Nm
What it represents
N dependency is the negate or exclusive-OR relationship. When the Nm affecting input is at its internal 1 state, each affected input or output labelled m is complemented. At 0 it has no effect. The result is a controllable inverter folded into the device symbol.
This notation appears on devices with selectable output polarity, such as programmable inverting or non-inverting buffers. Reading the N label tells the drafter that the same pin can produce either sense depending on the control input.
The label does not indicate when the polarity may be changed during operation. That is a matter of device timing and system design.
How to read it
- An active N input inverts every terminal labelled with its number.
- Check the state of the N control in each operating mode.
Information to show or reference
- Label the polarity control input as Nm.
- Mark affected terminals with m.
- State the default polarity in the sheet notes.
A distinction that matters
Fixed output negation is a circle or triangle; N dependency makes the negation switchable.
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)
N (negate) dependency description.
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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