Seven Segment Display

Seven Segment Display

• A display consisting of seven LEDs arranged in seven segments is called seven segment display. It is shown in the Fig. 1.20.1. The seven LEDs are arranged in a rectangular fashion and are labeled A through G. Each LED is called a segment because it forms a part of the digit being displayed. An additional LED is used for the indication of a decimal point (DP).

 • By forward biasing different LEDs we can display the digits 0 through 9. For example, to display a zero, the LEDs A, B, C, D, E and F are forward biased. To light up a 5, we need to forward bias segments A, F, G, C, D. Thus in a seven segment display depending upon the digit to be displayed, the particular set of LEDs is forward biased. The various digits from 0 to 9 which can be displayed using seven segment display are shown in the Fig. 1.20.2.

• A seven segment display can also display the capital letters A, C, E and F and also small letters b and d. Microprocessor kits often use such seven segment displays.

1. Types of Seven Segment Display

The two types of seven segment display are available called,

1) Common anode type

2) Common cathode type

Common anode type

• In this type, all anodes of LEDs are connected together and common point is connected to + Vcc which is positive supply voltage. A current limiting resistor is required to be connected between each LED and ground. The connection is shown in the Fig. 1.20.3.

Common cathode type

• In this type, all cathodes of LEDs are connected together and common point is connected to the ground. A current limiting resistor is connected between each LED and the supply + Vcc. The anodes of the respective segments are to be connected to + Vcc for the required operation of LEDs. The connection of common cathode type display is shown in the Fig. 1.20.4.

Review Question

1. List and explain the applications of LED.

AU : Dec.-12, Marks 3