74LS08 ICis a member that 74XXYY IC series. There are four and also gates in the chip and each gate have two inputs, thus thename QUADRUPLE 2- INPUT and GATE. The gates in the chip room designed by SCHOTTKY TRANSISTORS for high speed logic operations.

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74LS08 pen configuration

74LS08 is a 14 pen IC. The chip is obtainable in various packages and is chosen depending upon requirement. The summary for each pin is provided below.

Pin Number


AND door 1


A1-INPUT1 of door 1


B1-INPUT2 of door 1



AND gate 2


A2-INPUT1 of door 2


B2-INPUT2 of gate 2



AND door 3


A3-INPUT1 of door 3


B3-INPUT2 of door 3



AND door 4


A4-INPUT1 of gate 4


B4-INPUT2 of door 4





GND- linked to ground


VCC-Connected to hopeful voltage to carry out power come all four gates

Features and Specifications

Operating voltage range: +4.75 to +5.25VRecommended operating voltage: +5VMaximum it is provided voltage:7VMaximum current permitted to attract through each gate output: 8mATTL outputsLow power consumptionTypical climb Time: 18nsTypical loss Time: 18nsOperating temperature:0°C come 70°CStorage Temperature: -65°C come 150°C

74LS08 Equivalents

SN54LS08, IC 7408, HEF4081, any kind of two transistors have the right to be reconfigured to form a and gate.

Whereto use 74LS08 IC

There are numerous applications of IC 74LS08. A few mentioned below.

1. The chip is basically provided where and logic operation is needed. There are four and gates in the chip, we can use one or all entrances simultaneously.

2. The chip is supplied in equipment where high speed and also operation is needed. As mentioned previously the gateways in the chip space designed by SCHOTTKY TRANSISTORS to do the convert delays of gateways less. As such the chip have the right to be supplied for high speed and also operations.

3. 74LS08 is one of cheapest IC existing in market for and logic operation. That is really popular and also is easily accessible everywhere.

4. The chip gives TTL outputs which are required in some systems.

How to use 74LS08 IC

The four and also gates in the chip mentioned earlier are linked internally as presented in diagram below.


Each and gate here performs and operation for two logic inputs. For instance gate1 performs and also operation in between A1 and also B1 and provides output at Y1 terminal.

The truth table of and gate is offered as,



AND Output













For establish the over truth table let us take a simple AND gate application circuit as shown below.


For much better understanding the inner working allow us consider the simplified interior circuit of and also gate as displayed below.


In the circuit two transistors are connected in collection to type a and also gate. The 2 inputs of and also gate are propelled out indigenous bases of the two transistors. These two inputs are connected to buttons to readjust the logic of inputs. Calculation of the and gate is the voltage throughout resistor R1. This output is linked to a LED D1 trough a present limiting resistor R2. This LED is linked to detect the state of output.

The circuit working deserve to be explained in couple of stages below:

Stage1: once both buttons are not pressed. In this state the present flow v base the both transistors will certainly be zero.Because base current is zeroboth transistors Q1 and also Q2 will certainly be OFF. For this reason the full supply voltage VCC appears throughout the transistors Q1 and also Q2. Due to the fact that total VCC appears throughout transistors the drop throughout resistor R1 will be zero. Due to the fact that output is nothing however voltage across resistor R1 it will certainly be LOW. So as soon as INPUTS = LOW, calculation = LOW.

Stage2: When any kind of one of the buttons is pressed.In this state the loved one transistor will certainly be ON leaving the various other OFF. The top top transistor will certainly act as short circuit and also OFF transistor plot as open circuit having total VCC appearing throughout it. Through that the drop across resistor R1 will be zero. Because output is nothing but voltage throughout resistor R1 it will be LOW. So once one intake = LOW, output = LOW.

Stage3:When both buttons are pressed. Both transistors will certainly be ON and voltage throughout both the them will certainly be zero.At this time the full VCC appears across resistor R1.Because calculation is nothing however voltage across resistor R1 it will be HIGH. So once both intake = HIGH, calculation = HIGH.

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After verifying the three states, you deserve to tell the we have actually satisfied the above truth table. We can also write the logic equation for and gate through the truth table and also is, Y = A.B or A+B

Like this we have the right to use each door of the chip depending upon requirement.


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