The H-bridge arrangement is generally used to reverse the polarity of the motor, but can also be used to ‘brake’ the motor, where the motor comes to a sudden stop, as the motor’s terminals are shorted, or to let the motor ‘free run’ to a stop, as the motor is effectively disconnected from the circuit. The following table summarises operation, with S1-S4. S1 S2 S3 S4 Result 1 0 0 1 Motor moves right 0 1 1 0 Motor moves left 0 0 0 0 Motor free runs 0 1 0 1 Motor brakes 1 0 1 0 Motor brakes
The L293D is an extremely popular Motor Driver IC(H-Bridge) for controlling DC and bipolar stepper motors.
You can use this IC to control 2 DC motors with individual directional and speed control or just switch on and off 4 DC motors. This IC can be used to control DC motors with microcontrollers and also other analog circuits.
The L293D can control motors which consume upto 600 mA of current. For higher current requirements go for the L293NE, which is pin compatible with the L293D and can deliver upto 1 A of current on each channel.