A seven segment LED display consists segmental displays,in which each segment employ a single LED.

Conventional seven-segment LED display have the decimal points i.e.,the 8th segment. The wiring pattern is simplified by making one terminal common to all LEDs and other terminal corresponding to different segments.The terminals can be either of the common anode(CA) form or common cathode(CC) form,shown in fig.

A typical static signal digit 7 segment LED display system.

Common anode type displays require an active low (or current sinking) configuration for code converter circuitry,whereas an active high (or current sourcing) output circuit is necessary for common-cathode LED type display.