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I have a circuit that is set up to run motors using an Arduino and an H-Bridge chip. It works fine with the L293D chip but when I replace it with the SN754110NE chip it stops working.

As far as I can tell, the pinouts for both chips are identical so I'm not sure what the problem is.

Does anyone know what are the differences that would make one chip work but not the other?

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    \$\begingroup\$ Could you post your circuit or at least how the mentioned ICs are connected? \$\endgroup\$ – abdullah kahraman Jan 1 '12 at 21:59
  • \$\begingroup\$ Also, what is the frequency of your input signal? \$\endgroup\$ – abdullah kahraman Jan 1 '12 at 22:05
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    \$\begingroup\$ At a quick skim the two look very similar at the connection level - pinouts, enable signal levesl, supply com=nnection, ... . Suggests something subtle. Your circuot and all possible parameters (speed, voltag e, frequencies, ... )... may help. \$\endgroup\$ – Russell McMahon Jan 2 '12 at 0:54
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    \$\begingroup\$ Defining what you mean exactly by "not working" would also be helpful. They are so similar (the SN754410 is suggested as a replacement for the L293 in the datasheet) it seems to me it's possible something else may be up, like the chip is faulty or going into thermal shutdown if a different package. \$\endgroup\$ – Oli Glaser Jan 2 '12 at 9:52
  • \$\begingroup\$ no They cannot be considered plug compatible. but similar. \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 Apr 11 '12 at 10:34
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This is caused because the SN754410 H-Bridge does not have diodes. Although the data sheet shows diodes on the drawing, they are ESD diodes which could probably explain your issue. The SN754410 is however compatible pin for pin with the L293. The reason is because those do not have diodes. The L293D however is also compatible pin for pin and has diodes, hence the "D" in L293D.

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  • \$\begingroup\$ Section 9.3.1 of the TI data sheet says: "Four high current and high voltage outputs feature clamp diodes for inductive load driving." So the above reason for it not working doesn't seem to stack up. \$\endgroup\$ – user105985 Apr 6 '16 at 13:49

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