L293D

The L293D is a versatile 16-pin quadruple high-current half-H driver designed to provide bidirectional drive currents for motors, but mastering its pinout and operation requires careful attention to detail. The IC is divided into two halves: Pins 1, 2, 7, and 8 control one motor, while Pins 9, 10, 15, and 16 control the second, with each half featuring an Enable pin (1 and 9) that must be pulled high to activate the outputs. A critical design feature is the separation of power supplies: Vcc1 (Pin 16) powers the internal logic at 5V, whereas Vcc2 (Pin 8) provides the higher voltage needed for the motors themselves. To prevent permanent damage, users must ensure they do not exceed the 600mA per channel current limit and should always connect all four ground pins (4, 5, 12, and 13) to a heat sink or a large copper area to manage thermal dissipation. Common mistakes that lead to "magic smoke" or erratic behavior include forgetting to tie the grounds of the logic and motor power supplies together, failing to provide the logic voltage to Pin 16, or attempting to drive high-stall-current motors without checking the L293D's relatively low peak threshold.