# IEC BCD-to-seven-segment decoder

Canonical URL: https://eloragrid.ai/symbols/iec-bcd-to-seven-segment-decoder
Publisher: Elora Grid
Updated: 2026-10-28
Lookup label: BCD/7SEG
Drawing use: Schematic
Reference families: IEC, Manufacturer

## Symbol convention

Convention: IEC
Form: X/Y coder with BCD/7SEG qualifier and segment outputs a to g
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.

IEC coder marked BCD/7SEG converting a 4-bit BCD input into seven segment-drive outputs a to g.

## In plain English

### What does IEC BCD-to-seven-segment decoder mean?

The BCD-to-seven-segment decoder is an X/Y coder with the additional drawing mark BCD/7SEG, sometimes written BCD/7-SEG. Inputs are weighted 1, 2, 4 and 8 and outputs are labelled a to g for the display segments. Many devices add lamp test and blanking inputs shown with their own labels.

### A simple example

Seven-segment decoders appear on drawings for local numeric displays, counters and older instrument panels. The output stage type matters: many drivers have open-collector outputs intended to sink LED or lamp current, which should be shown with the open-circuit additional drawing mark.

### What the drawings help you do

The symbol does not state segment current, display type (common anode or cathode) or how non-BCD codes are displayed. Those come from the device data and display selection.

### This particular reference

IEC coder marked BCD/7SEG converting a 4-bit BCD input into seven segment-drive outputs a to g. A BIN/OCT decoder activates one output per code; this coder activates a pattern of segments.

### Terms

- Signal: Electrical information passed between devices, rather than necessarily the main power supply.
- Rating: A value stating the conditions for which equipment is specified.
- Schematic: A drawing showing function and connections rather than physical appearance.

Concept diagram: Identify the device and form → Read the connections and state → Check the equipment reference
A guide to reading this reference. The original symbol illustration and its drawing notes appear below; these boxes are not a wiring diagram.

- [Overview of IEEE Standard 91-1984: explanation of logic symbols (SDYZ001A)](https://www.ti.com/lit/ml/sdyz001a/sdyz001a.pdf)
- [SN74LS47 BCD-to-seven-segment decoders/drivers](https://www.ti.com/lit/ds/symlink/sn74ls47.pdf)


## What it represents

The BCD-to-seven-segment decoder is an X/Y coder with the qualifier BCD/7SEG, sometimes written BCD/7-SEG. Inputs are weighted 1, 2, 4 and 8 and outputs are labelled a to g for the display segments. Many devices add lamp test and blanking inputs shown with their own labels.
Seven-segment decoders appear on drawings for local numeric displays, counters and older instrument panels. The output stage type matters: many drivers have open-collector outputs intended to sink LED or lamp current, which should be shown with the open-circuit qualifier.
The symbol does not state segment current, display type (common anode or cathode) or how non-BCD codes are displayed. Those come from the device data and display selection.

## How to read it

- Outputs a to g map to display segments.
- Check output type and display common connection.

## Information to show or reference

- Label segment outputs a to g.
- Show lamp test and blanking inputs where used.
- Show current-limiting resistors and display wiring.

## Important distinction

A BIN/OCT decoder activates one output per code; this coder activates a pattern of segments.

## Facts

- Qualifier: BCD/7SEG
- Example device family: BCD-to-seven-segment decoders/drivers
- Artwork scope: Original educational illustration; consult the applicable standard and the selected device documentation for the exact graphic

## Public references

- [Overview of IEEE Standard 91-1984: explanation of logic symbols (SDYZ001A)](https://www.ti.com/lit/ml/sdyz001a/sdyz001a.pdf) — Texas Instruments. Lists BIN/7-SEG style coder designations.
- [SN74LS47 BCD-to-seven-segment decoders/drivers](https://www.ti.com/lit/ds/symlink/sn74ls47.pdf) — Texas Instruments. Manufacturer BCD-to-seven-segment decoder/driver documentation.

## Graphic scope

Independent original educational concept illustration by Elora Grid. Not a certified standards graphic or manufacturer footprint. Unitless; not to scale. Original artwork licence: https://creativecommons.org/licenses/by/4.0/. Publisher material is linked only.