For better understanding the internal working let us consider the simplified internal circuit of AND gate as shown below. In the circuit two transistors are connected in series to form a AND gate. The two inputs of AND gate are driven out from bases of the two transistors. These two inputs are connected to buttons to change the logic of inputs.

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Gate AND gate is a digital circuit used to convert the logic state to a specific logic. In AND gate two logics state signals are used. A single AND gate uses two input pins and one output pin. The single AND gate can be made easily by using transistors and resistors or diodes. Every AND gate can be used separately without affecting the others. IC 74LS08 uses only one single power supply and it also comes in multiple packages to solve the requirement according to the circuit.

The IC 74LS08 is smaller in size and it has a much faster speed which makes it reliable in every kind of device. A4 Pin 12 will be used as the first input pin of forth AND gate.

B4 Pin 13 will be used as the second input pin of forth AND gate. IC 74LS08 has a much fast operating speed. It is much cheaper and easy to operate. Its output comes in TTL, which makes it operate able with most of the devices and microcontrollers. A single AND gate can be used without affecting the other ones. A single power supply can turn all four gates. The voltage recommended for IC should be 5 volts but IC can hold up to 7 volts maximum.

The IC gives 8mA maximum current at its outputs. It can operate in the temperature range from 0 to 70 degree but it also has the ability to store the temperature of to degrees. The IC is smaller in size and comes in multiple packages which make it reliable for any small size devices. The AND gate has three types of combinations and every combination has the same outputs on specific inputs.

We will use here transistor-based AND gate. In transistor-based AND gate the basic circuit consisting of two transistors which are used as a switch to change the state on output on different inputs. In IC 74LS08 both transistors will be connected in series. The power will be connected with the collector of the first transistor and output will be received on the emitter of the second transistor.

The two inputs will be given to the base of both transistors. The inputs will let the current flow from the transistors. When the Input signal will be HIGH on both inputs then current could flow through the transistors and full voltages will be received on the output pin.

In other cases, if only one pin will be LOW in the circuit then the output will be LOW because there is no flow of current from the transistors. No matter which type of AND gate we use the output will always the according to the following table which is known as a truth table.


74LS08 Two Input Quadruple AND Gate IC



IC 74LS08 Datasheet And Pinout – Quad 2-Input AND Gates Chip



74LS08 Integrated Circuit (IC)


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