l293 motor driver

foTONICS

Sep 30, 2011
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The datasheet says the motor logic inputs are TTL compatible. I was playing around with a prototype and accidently wired it up as 0 and 12 V instead of 0 and 5 but the circuit behaved as expected. can this chip handle 12V on its input pin or will it become damaged after a while? I can't find anything on the datasheet except that it says TTL compatible.
 

Harald Kapp

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Nov 17, 2011
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The datasheet states under "absolute maximum ratings" (page 4) Vin(max)=7V.
You may have been lucky and your chip may have survived. However, chances are that it has been damaged and the defect will show later in the form of premature chip death, unreliable operation or any kind of "strange" behaviour.

Better get a new chip.

Since logic High input curent is max. 100µA, you can add at least some protection to the inputs by adding a series resistor to limit input current in case of overvoltage. To make it even more foolproof, add a 6.2´V Zener diode from the input to GND.
 
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