The L293 and L293D are quadruple high-current half-H drivers. The L293 is designed to provide bidirectional drive currents of up to 1 A at voltages from 4.5 V to 36 V. The L293D is designed to provide bidirectional drive currents of up to 600-mA at voltages from 4.5 V to 36 V. All inputs are TTL compatible. Each output is a complete totem-pole drive circuit, with a Darlington transistor sink and a pseudo-Darlington source.
WHERE TO USE?
The most common use of bidirectional current buffers is to drive a motor in both directions. Both devices are also used to drive inductive loads such as relays, solenoids, dc and bipolar stepping motors, as well as other high-current/high-voltage loads in positive supply applications.
HOW TO USE?
Drivers are enabled in pairs, with drivers 1 and 2 enabled by 1,2EN and drivers 3 and 4 enabled by 3,4EN. When an enable input is high, the associated drivers are enabled and their outputs are active & in phase with their inputs. When the enable input is low, those drivers are disabled, and their outputs are off and in the high-impedance state.
This one bidirectional current buffer IC can be used to drive 2 motors simultaneously as shown:
HOW IT WORKS?
Now the working of the both motors is controlled by the inputs 1A, 2A, 3A, 4A & 1,2EN & 3,4 EN and the inputs can be controlled using micro-controller or using switches etc. The following tables illustrate the working of both motors according to the inputs:
| 1A | 2A | 1,2EN | 1Y | 2Y | MOTOR1 |
| X | X | 0 | Z | Z | STOP |
| 1 | 0 | 1 | 1 | 0 | RUNS CLOCKWISE |
| 0 | 1 | 1 | 0 | 1 | RUNS ANTI-CLOCK |
| 0 | 0 | 1 | 0 | 0 | STOP |
| 1 | 1 | 1 | 1 | 1 | STOP |
| 3A | 4A | 3,4EN | 3Y | 4Y | MOTOR2 |
| X | X | 0 | Z | Z | STOP |
| 1 | 0 | 1 | 1 | 0 | RUNS CLOCKWISE |
| 0 | 1 | 1 | 0 | 1 | RUNS ANTI-CLOCK |
| 0 | 0 | 1 | 0 | 0 | STOP |
| 1 | 1 | 1 | 1 | 1 | STOP |