L298 MOTOR Driver

L298 IC:

Description:

A very popular and reasonably priced all-in-one H-bridge motor driver is the L298. It can control two motors, not just one. It can handle 2 amps per motor, though to get the maximum current be sure to add a heat sink. The L298 has a large cooling flange with a hole in it, making it easy to attach a homebrew metal heat sink to it.If there’s a downside to the L298 it’s that it comes in a special “Multiwatt 15” package, with 15 offset pins that don’t match the standard 0.100" spacing of breadboards. But with care, the pins can be rebent as needed. Or you may prefer to simply get a breakout board for the L298, which is a small circuit board with holes drilled in it to accept the chip. You then plug the breakout board into your breadboard. Problem solved.The schematic below shows a basic connection diagram for controlling two motors using the L298 motor bridge IC. There are three input pins for each motor: Input1, Input2, and Enable1 controls Motor1. Input3, Input4, and Enable2 controls Motor2. The motors connect to Output1/Output2 and Output3/Output4, as shown.

The L298 uses two different supply voltages. The voltage on pin 9 powers the chip itself and should be 5 volts. The voltage on pin 4 supplies the motors, and it can be up to 46 volts.

Let’s look at how to control just one of the motors, Motor1. In order to activate the motor, the Enable1 line must be HIGH. You then control the motor and its direction by applying a LOW or HIGH signal to the Input1 and Input2 lines, as shown in this table.

Input1	Input2	Action
LOW	LOW	Motor breaks and stops*
HIGH	LOW	Motor turns forward
LOW	HIGH	Motor turns backward
HIGH	HIGH	Motor breaks and stops*

* To coast a motor to a slower stop, apply a LOW signal to the Enable1 line.

The L298 does not have built-in protection diodes, so you’ll need to add those. The datasheet for the L298 specifies “fast recovery” 1-amp diodes; an inexpensive selection is the 1N4933, available from most online electronic parts outlets.

L298 based Motor Driver

Fig. of Motor Driver

Features

·         Maximum motor supply voltage: 46V

·         Maximum motor supply current: 2A per motor

·         Current Sense for each motor

·         Heat sink for better performance

·         Power-On LED indicator

 Using the board to drive motor

Motor driving is extremely simple with the board. The board has two ChannelsA and B. It has 2 inputs and 2 corresponding outputs for each Channel. Each channel also has an enable pin and a sense pin. The Input pins are the labelled as INP A and INP B. The enable pin is labeled As EN A and EN B, and the sense pin is labelled as SNS A and SNS B.To drive a DC motor in a particular channel, the enable pin of the Channel has to be supplied with a logic high (+5V) signal. Then, a logic high signal has to be supplied to the input pins to control the direction of the motor. Supplying logic high to any one of the input pins will drive the DC Motor in one direction. On supply logic high to the other Input pin, the motor will run in the opposite direction. Supplying logic high to both input pins will brake the rotation of the motor and Supplying a logic low (0V or Gnd) signal to both the input pins will allow the DC motor to rotate freely.The sense pin can be used to sense and limit the amount of current the motor in corresponding channel is consuming. By default this option is not enabled on the board and the sense pin is directly connected to GND through a jumper.

 Internal and external logic supply for the board

   

The L298 requires an input voltage of 5V for its operation. The board has an on board 5 V regulator (LM7805) for the same. It takes the motor input voltage and regulates it to 5V. The regulated voltage can also be supplied to external circuits and can be tapped through the 5V and Gnd header

The on board voltage regulator can work on a maximum input voltage of 35 V. If you wish to drive motors with voltages greater than 35 V, you will have to supply external 5 V for the board, and cut of the input supply to the on board regulator. This will prevent it from getting damaged due to a high input voltage. You can do this by de-soldering the jumper on the bottom side of the board between Pin 1 of the voltage regulator and the+ve Input Voltage pin.