A seven segment display is mostly use in electronics device for decimal numbers from 0 to 9 and in some cases, basic characters. The use of seven segments is calculator, microwave oven, automatic washing machine, radio, digital watch etc. The 7 Segment Display uses light emitting diodes (LEDs) which made it more popular, whereas of late liquid crystal displays (LCD) displays have also come into use. To display numeric information like number and some special characters. The LEDs are made of semiconductor material which emits either visible light or invisible infrared light when forward biased. Remote controls generate invisible light.
The light emitting diode (LED) is a PN junction diode which radiates light energy in the form of photons. The emission of photons occurs when diode is forward bias. The range of visible light from blue to red to orange, is decided by the spectral wavelength of the emitted light which itself is dependent upon the mixture of the various impurities in semiconductor.
The LED has much advantage in electronics and electrical circuit because it has less price, small size, low power consumption and long life. But the main advantage of LED is that because of their small size and low power consumption, some of LED can be connected together within one small and compact package producing what is generally called a seven segment Display. It is also know as 7 segment Display.
Seven Segment Displays:
The seven segment is group of LED in a specific manner that display information in the form of text image and numbers which is an alternative to the more complex dot matrix displays. Its applications are digital watch, calculator, and electronics meter for display outputs. It consists of seven LEDs which are assembled like numerical 8.
The seven segment display is also written as 7 segment displays because it consists of 7 LED arranged in a rectangular fashion as shown. Each of the seven LEDs is called a segment. When illuminated segment forms part of a numerical digit (both Decimal and Hex) to be displayed.
Working of Seven Segment Displays:
In 7 segment display, it has seven LEDs and it is arrange in proper manner which is shown in figure. The circuit configuration of 7 segment display voltage at different pin can be applied at the same time. In the same way we can form the combinations to display numerals from 0 to 9. When all LED glow than the 8 number will show. If you disconnect segment “G” then that will result number 0 and alphabets A, B, C, D, E, and F.
It cannot show the all alphabetical, some alphabetical characters shown on display is A, B, C, D, E, and F because it is use to representation of hexadecimal digits.
Seven segment display of truth table
We can produce a truth table for each decimal digit and its truth table is given below:
For ON and OFF of light emitting diode we required a Boolean expression for decimal digits. It is control by an externals device where different type of controller are use to communicate with these external devices, like switches, keypads, and memory.
Seven-segment LED circuit configuration
LED display devices have two kinds of circuit:
- Common Anode – when the common pin is positive.
- Common Cathode – when the common pin is negative.
Seven segment display pinout
It is a made of seven light emitting diode. It is made of semiconductor material which emits the energy in the light from. The arrangement of light emitting diode is shown in figure which performs all decimal number and some alphabet character by displaying different combinations of segments.
Types of Seven Segment Displays:
The display common pin is generally used to identify which type of 7-segment display it is. As each light emitting diode have two connecting pins. One is “anode” and other is “cathode”. There are therefore two types of seven segment display called: Common Cathode (CC) and Common Anode (CA).
The difference between two types display, as their name suggest, is that the common anodes of all the segment is connected together and the common cathode has all the cathodes of all segment is connected together.
- The Common Cathode (CC)– In the common cathode display, all the cathode of light emitting diode is connected together or common with logic “0” or ground. The individual segment will illuminate by application of logic “1 or “HIGH”, signal via a current limiting resistor to forward bias the individual Anode terminals (a-g).
Common Cathode 7-segment Display
Table: Display numbers on a seven segment display in common anode configuration.
| Number | g f e d c b a | Hex code |
| 0 | 1000000 | C0 |
| 1 | 1111001 | F9 |
| 2 | 0100100 | A4 |
| 3 | 0110000 | B0 |
| 4 | 0011001 | 99 |
| 5 | 0010010 | 92 |
| 6 | 0000010 | 82 |
| 7 | 1111000 | F8 |
| 8 | 0000000 | 80 |
| 9 | 0010000 | 90 |
- The Common Anode (CA)– in this configuration the anode of all light emitting diode is common and this common node is connected to logical “1”. The individual segments are illuminated by applying a ground, logic “0” or “LOW” signal via a suitable current limiting resistor to the Cathode of the particular segment (a-g).
Common Anode 7-segment Display
Table: Display numbers on a seven segment display in common cathode configuration
| Number | g f e d c b a | Hex Code |
| 0 | 0111111 | 3F |
| 1 | 0000110 | 06 |
| 2 | 1011011 | 5B |
| 3 | 1001111 | 4F |
| 4 | 1100110 | 66 |
| 5 | 1101101 | 6D |
| 6 | 1111101 | 7D |
| 7 | 0000111 | 07 |
| 8 | 1111111 | 7F |
| 9 | 1001111 | 4F |
A common anode segment is more popular in many logic circuits can sink more current than they can source.
Arduino seven segment display
A interfacing of LED display with Arduino is shown below:
Applications of Seven Segment Displays:
Common applications of seven segment displays are in:
- It is use in Digital clocks
- LED display is use in Clock radios
- It is found in Calculators
- Wristwatchers and Speedometers
- Motor-vehicle odometers
- Radio frequency indicators
Seven segment display datasheet
| PARTSTABLE | ||||||||||||||
|
PART |
COLOR |
LUMINOUSINTENSITY (µcd) |
At IF (mA) |
WAVELENGTH (nm) |
At IF (mA) |
FORWARDVOLTAGE M |
At lF (mA) |
CIRCUITRY |
||||||
| MIN | .TYP. | MAX. | MIN. | TYP. | MAX. | MIN. | TYP. | MAX. | ||||||
| TDS05150 | Orange red | 700 | 5000 | – | 10 | 612 | – | 625 | 10 | – | 2 | 3 | 20 | Common anode |
| TDS05150-LM | Orange red | 2800 | – | 9000 | 10 | 612 | – | 625 | 10 | – | 2 | 3 | 20 | Common anode |
| TDS05160 | Orange red | 700 | 5000 | – | 10 | 612 | – | 625 | 10 | – | 2 | 3 | 20 | Common cathode |
| TDS05160-LM | Orange red | 2800 | – | 9000 | 10 | 612 | – | 625 | 10 | – | 2 | 3 | 20 | Common cathode |
| TDSY5150(1) | Yellow | 700 | 4200 | – | 10 | 581 | – | 594 | 10 | – | 2.4 | 3 | 20 | Common anode |
| TDSG5150 | Green | 700 | 9500 | – | 10 | 562 | – | 575 | 10 | – | 2.4 | 3 | 20 | Common anode |
| TDSG5150-MN | Green | 4500 | – | 14000 | 10 | 562 | – | 575 | 10 | – | 2.4 | 3 | 20 | Common anode |
| TDSG5150-N | Green | 7000 | – | 14000 | 10 | 562 | – | 575 | 10 | – | 2.4 | 3 | 20 | Common anode |
| TDSG5160 | Green | 700 | 9500 | – | 10 | 562 | – | 575 | 10 | – | 2.4 | 3 | 20 | Common cathode |
| TOSG5160-MN | Green | 4500 | – | 14000 | 10 | 562 | – | 575 | 10 | – | 2.4 | 3 | 20 | Common cathode |
| TOSG5160-N | Green | 7000 | – | 14000 | 10 | 562 | – | 575 | 10 | – | 2.4 | 3 | 20 | Common cathode |
