L293D MOTOR DriVER

             L293D DIP16 Package

Description:-

L293D is a typical Motor driver or Motor Driver IC which allows DC motor to drive on either direction. L293D is a 16-pin IC which can control a set of two DC motors simultaneously in any direction. It means that you can control two DC motor with a single L293D IC. Dual H-bridge Motor Driver integrated circuit (IC).The l293d can drive small and quiet big motors as well

capable of driving high voltage motors using TTL 5V logic levels. They can drive 4.5V up to 36V at 1A continuous output current!

L293D Connections

L293D is a 16 pin IC which comes in a DIP Package. Its pin configuration is shown below.

              L293D Pin Configuration

Now let’s have a look at its connections for bidirectional motor control.

                L293D Based Motor Driver

In this way, we can have bidirectional control over two motor. Let’s have a summary of connections:

o    There are two enable (EN) pins, pin 1 and pin 9. Pin 1 EN enables the motor M1 whereas pin 9 EN enables motor M2.

o    Connect motor M1 across OUTPUT1 and OUTPUT2 i.e. across pins 3 and 6.

o    Connect motor M2 across OUTPUT3 and OUTPUT4 i.e. across pins 11 and 14.

o    The inputs for motor M1 is given across INPUT1 and INPUT2 i.e. across pins 2 and 7.

o    The inputs for motor M2 is given across INPUT3 and INPUT4 i.e. across pins 10 and 15.

o    Connect GROUND pins 4, 5, 12 and 13 to ground.

o    Connect pin 16 to Vcc (=5V) and pin 8 to Vs (battery, 4.5V~36V).

As per the diagram, the inputs of motor M1 are M1-A and M1-B, whereas inputs of motor M2 are M2-A and M2-B.

Now consider the following cases for motor M1:

o    M1-A = 1 and M1-B = 0 → M1 moves clockwise (say). Then

o    M1-A = 0 and M1-B = 1 → M1 moves counter-clockwise.

o    M1-A = 0 and M1-B = 0 → M1 stops.

o    M1-A = 1 and M1-B = 1 → M1 stops.

Similar cases can arise for motor M2:

o    M2-A = 1 and M2-B = 0 → M2 moves clockwise (say). Then

o    M2-A = 0 and M2-B = 1 → M2 moves counter-clockwise.

o    M2-A = 0 and M2-B = 0 → M2 stops.

o    M2-A = 1 and M2-B = 1 → M2 stops.

Suppose if you need to control only one motor at a time, you need to enable that particular EN pin. Enabling both pins at the same time will drain your battery unnecessarily.

Concept

It works on the concept of H-bridge. H-bridge is a circuit which allows the voltage to be flown in either direction. As you know voltage need to change its direction for being able to rotate the motor in clockwise or anticlockwise direction, Hence H-bridge IC are ideal for driving a DC motor.

In a single l293d chip there two h-Bridge circuit inside the IC which can rotate two dc motor independently. Due its size it is very much used in robotic application for controlling DC motors. Given below is the pin diagram of a L293D motor controller.

There are two Enable pins on l293d. Pin 1 and pin 9, for being able to drive the motor, the pin 1 and 9 need to be high. For driving the motor with left H-bridge you need to enable pin 1 to high. And for right H-Bridge you need to make the pin 9 to high. If anyone of the either pin1 or pin9 goes low then the motor in the corresponding section will suspend working. It’s like a switch.

Working of L293D

The there 4 input pins for this l293d, pin 2,7 on the left and pin 15 ,10 on the right as shown on the pin diagram. Left input pins will regulate the rotation of motor connected across left side and right input for motor on the right hand side. The motors are rotated on the basis of the inputs provided across the input pins as LOGIC 0 or LOGIC 1.

In simple you need to provide Logic 0 or 1 across the input pins for rotating the motor.

L293D Logic Table

Lets consider a Motor connected on left side output pins (pin 3,6). For rotating the motor in clockwise direction the input pins has to be provided with Logic 1 and Logic 0.   

• Pin 2 = Logic 1 and Pin 7 = Logic 0 | Clockwise Direction

• Pin 2 = Logic 0 and Pin 7 = Logic 1 | Anticlockwise Direction

• Pin 2 = Logic 0 and Pin 7 = Logic 0 | Idle [No rotation] [Hi-Impedance state]

• Pin 2 = Logic 1 and Pin 7 = Logic 1 | Idle [No rotation]

In a very similar way the motor can also operated across input pin 15,10 for motor on the right hand side.