In this lecture, we are going to learn about the 7 Segment Display in very detail. We will learn the 7 Segment Display types, 7 Segment Display pin configuration, and how they will connect with the decoder circuit. So before starting to get the full knowledge of the 7-Segment Display, let’s see the basic definition of What 7-Segment Display is.
What is a 7-Segment Display?
A 7-segment display is a simple electronic component with seven individual segments that can be turned on or off to represent numerical digits (0-9) and a few letters (A, b, C, d, E, F, and sometimes G).
The below figure shows the construction of a seven-segment display.
We can display any number from 0 to 9 by turning on various combinations of the segments as shown in the table.
Actually, each segment (a to f) is nothing but an LED in a segment form. Their connection leads are brought out and by applying a forward voltage to the segments to be turned on, we can display any number between 0 and 9.
For example, if we want to display the number 7 then the segments a, b, and c should be turned on and all other segments should be off. Similarly, the other number can be displayed as shown in the figure.
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7 Segment Display Types
There are two types of seven-segment LED displays:
- Common Anode 7 Segment Display
- Common Cathode 7 Segment Display
Common Anode 7 Segment Display
A common anode seven-segment display is shown in the below figure.
Here as the name indicates the anode terminals of all LED segments are connected together, which means all connected segments will be given to Vcc.
A current limiting resistor is externally connected in series with each segment. The common anode point is connected to the Vcc and the cathode of the segments to be illuminated is connected to the Ground.
Common Cathode 7 Segment Display
A common cathode seven-segment display is shown in the below figure.
As the name indicated, the cathode terminal is made common and all the anode terminals are brought out separately.
A current limiting resistor is externally connected in series with each segment. The common cathode point is connected to the ground and the anodes of the segments to be illuminated are connected to positive supply voltage Vcc.
7 Segment Display with Decoder
The use of a Decoder or driver for driving the seven-segment display will be discussed in this section.
Many times the 7-segment LED displays are connected to the output of digital ICs such as counters.
Now as the counter output is in the BCD (binary coded decimal) form, which has only four lines, it can’t drive the 7 segment display directly.
Therefore, we have to use a BCD to seven-segment decoder IC between the counter output and seven-segment display.
Common Anode 7 Segment Display with Decoder
The common anode type 7 segment display is being used in the below figure.
The decoder accepts a 4-bit BCD count from a counter, converts it into a seven-bit code suitable for the seven-segment display (a’ to g’), and drives the display.
To turn on a segment, the corresponding decoder output goes low and sinks current (for common anode display).
A current limiting resistance is connected in series with each segment.
Common Cathode 7 Segment Display with Decoder
The decoder has to source the current in this case.
The common anode point is connected to Vcc. i.e., positive supply voltage.
A current limiting resistor is externally connected in series with each segment.
The cathode of the segments to be turned on is connected to the ground. For example, for displaying 7 the cathode of segments a, b, and c should be connected to the ground.
Also Read: Multiplexer in Digital Electronics
Application of Seven-Segment Display
Here are some applications of the segment display are as follows:
| Applications | Description |
|---|---|
| Digital Clocks | Used to display hours, minutes, and seconds in various timekeeping devices. |
| Counters | Utilized in applications such as people counters and production line counters. |
| Stopwatches and Timers | Essential for measuring elapsed or remaining time accurately. |
| Temperature Displays | Show temperature values in digital thermometers and weather stations. |
| Digital Multimeters | Provide clear readouts for voltage, current, and resistance measurements. |
| Calculators | Used for numeric input and output in pocket calculators. |
| Scoreboards | Display game scores, time remaining, and other sports-related information. |
| Gas Pump Displays | Show the amount of fuel dispensed and the total cost at gas stations. |
| Cash Registers | Display prices, total amounts, and transaction-related data in retail. |
| Appliance Displays | Common in home appliances like microwaves and alarm clocks. |
| Indicators and Alarms | Serve as visual indicators and error displays in various systems. |
| Educational Kits | Used in electronics kits to teach students about displays and coding. |
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FAQs on 7-Segment Display
What is a 7-segment display?
A seven-segment LED is a digital display module specialized to display numerical information.
Is a 7-segment display LED or LCD?
Seven-segment displays may use a liquid crystal display (LCD), and a light-emitting diode (LED) for each segment.
What is the use of a 7-segment display in daily life?
Seven-segment display is a form of electronic display used for displaying alpha-numeric characters.
How many types are in a 7-segment display?
here are two types of LED 7-segment displays: common cathode (CC) and common anode (CA). The difference between the two displays is the common cathode has all the cathodes of the 7-segments connected directly together and the common anode has all the anodes of the 7-segments connected together.
How many LEDs are in a 7-segment?
Seven LEDs
What are the uses of 7 segments?
Seven-segment displays are widely used in digital clocks, electronic meters, basic calculators, displays in home appliances, cars, and various other electronic devices that display numerical information.
