I measured the resistance between the connectors of a 6V motor and found it to be about 4 ohms. I power the motor with 4 LR6 batteries, so 6 volts.
When I switch on the power to the motor, and just before it starts to turn, the momentary current going through the L293D chip is, I suppose:
I = V/R = 6/4 = 1.5 Amps
The L293D data sheet says the absolute maximum current permitted is 1200mA, and that for less than 100 microseconds. So 1500mA doesn’t seem like a good idea.
Should I put a small resistor (say, 2 ohms) between the L293D’s output pin and the motor? That would make 6 ohms in all with the 4 ohms of the motor’s windings and so 6V/6 ohms = 1 amp (<1.2 amp so OK).
I ask because I just googled “L293D circuit” and apparently no-one has ever thought it necessary (over 100 circuits and not a single one with a current-limiting resistor).
Conclusion: there’s something I don’t understand.
Does anyone know what I’m missing?