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I am considering buying one of the hbridge drivers referenced in the below tutorial, but when I looked at the comments underneath the second hbridges sparkfun page, kickback diodes were referenced and how one of the drivers has internal diodes but the other doesn't. I will be working with motors no more than 8V and much less than 1 A of current. Which of these drivers should I use and should I use kickback diodes with it also?
http://itp.nyu.edu/physcomp/Labs/DCMotorControl

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From the comments @ sparkfun (Specifically superbrad):

The L293D has internal flyback diodes, which catch what would otherwise be high voltage inductive noise (sometimes even in the kilovolts). With the SN754410, you must use external flyback diodes in your H-Bridge.

Even though you might feel like you can get away with it, it's a VERY bad idea to use the SN754410 without a flyback diode. It's not just the driver you have to worry about, it's your entire circuit (MCU, accelerometers, expensive XBee, etc.). Eventually, your luck will run out, even if you don't turn it on and off frequently.

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  • \$\begingroup\$ So are the internal diodes in the l293d strong enough to handle any of the loads I am dealing with? Or are they cheap things added just incase you decide to risk it? \$\endgroup\$ Feb 14 '11 at 12:36
  • \$\begingroup\$ The internal diodes are likely matched to the drivers power capacity, e.g. if the power devices in the L293 can handle the load, the internal clamp diodes should be able to handle the inductive kickback. I would imagine it is possible to get a big enough inductor that you could blow the clamp diodes, but you'd likely have to specifically search for it. Basically, assuming you're using the L293 to drive a normal motor, rather then a GIANT inductor, you should be fine. \$\endgroup\$ Feb 15 '11 at 1:59
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Always use flyback diodes when driving inductive loads with a transistor. Look for those that can pass at least as much current as the max bridge current and are labeled "flyback" or "fast recovery".

As for which one, I leave to someone else...

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