The Motor Drivers (L293D) 13

The Motor Drivers
Motor are high-powered devices in the world of digital electronics. A typical digital output can supply about 10 to 20 mA of current. A small magnet motor requires anywhere from 500 to 4000 mA of current. Special circuits are therefore required to drive motors

The H-Bridge Circuit.

H-bridge Circuit

A circuit known as the H-bridge (named for its topological similarity to the letter H) is commonly used to drive motors. in this circuit ( shown above), two of four transistors are selectively enabled to control current flow through a motor.

The H-bridge with left to right current flow

as shown above, an opposite pair of transistors( Transistor One and transistor three) is enabled, allowing current to flow through the motor. The other pair is disabled, and can be thought of as out of the circuit. by determining which pair of transistors is enabled, current can be made to flow in either of the two directions through the motor. Because permanent magnet motors reverse their direction of turn when the current flow is reversed, this circuit allows bidirectional control of the motor.

L293D

The L293D is a dual h-bridge driver IC. The IC is also referred to as a push-pull four channel driver. An h-bridge is ideal for driving motors. The L293D provides two h-bridges for driving both motors on the robot base. The motor direction is controlled by logic signals from the microcontroller. Two signals per motor are required to control the direction.