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I want to use the L293D to control 2 motors forward/backward. My question is if I set all inputs (A) high, do I have a short circuit? Because the driver gets really really hot.

Ribisl
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  • Sounds like you've miswired something else. Anyway, the L293D is a very old, lossy, and disappointing chip. – Chris Stratton Apr 30 '18 at 18:01
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    [It might be for this reason](https://electronics.stackexchange.com/questions/108686/l293-l298-and-sn754410-h-bridge-drivers-on-low-voltage-power-supply). Let me count the ways.... – Andy aka Apr 30 '18 at 20:54

2 Answers2

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The idea with an H-bridge type driver is that you can route DC through a motor in one direction or another by closing two switches at a time on far ends of the "H". If you close more than that, one whole side of your H-bridge is shorting the power supply to ground. This is likely to destroy the driver.

Bort
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    That's only possible if you have unique control over each switching element. As with most bridge chips, in this chip you do not, you can only control the upper and lower switches comprising each half-bridge together in complementary opposite. So you can drive both sides of a bridge high; but that won't cause a problem - unless something else is miswired, all it does it put a 0v difference across the load. – Chris Stratton Apr 30 '18 at 18:08
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The drivers are non inverting so logic “1” in @5V allows drivers to reach 2 Diode drops below Vcc2 unless shunted to ground.

If your load R is too low with excessive current or shorted from miswiring, it will get hot. Switch forward and reverse quickly generates twice the voltage from Back EMF so don't do this. Always stop first then reverse otherwise it will get hot.

Check the datasheets.

Tony Stewart EE75
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