< Rumor has it (from Adafruit, IIRC) that the > internal diodes are primarily for ESD-like protection and external > diodes should be used for flyback purposes. But like the original > poster says, it would be nice to see a definitive written statement to > that effect... (teacher hat on) Now, a question to the class: where do you go for answers? 'the=20 piclist'! OK, that's a good second, but actually the first choice should=20 be 'the datasheet'! Where to get the datasheet? Use www.findchips.com to find a supplier,=20 most (at least Digikey and Mouser) have a link to the datasheet on their=20 product page. You can of course just google, but your result will be=20 polluted by alldatasheets an other services that want to sell you info=20 that is otherwise freely available. Basic assumption when reading a datasheet: everything is forbidden,=20 except what is shown in the "normal (or recommended) operating=20 conditions" section. If you have a pair of scissors, cut out the=20 "absolute maximum ratings" section now and burn it. So for this chip we get http://focus.ti.com/lit/ds/symlink/sn754410.pdf=20 , which shows on page 4 the "VOKH High-level output clamp voltage" at=20 -0.5A and +1.0A. There is something I don't get, IMHO those two currents=20 should have the same sign, but it is clear that a clamp current is=20 allowed, at least up to 0.5 (or maybe 1.0) A. The clamp voltage is a=20 lousy 2.5V at 1A, so this is not a very good diode, but this is within=20 the "normal operating condition" for this chip. Of course, if you think=20 2.5V is way too much, or you fear you will exceed the maximum power=20 dissipation of the chip, or you are afraid these diodes will be too slow=20 (I see no switching time info), external (better!) clamping diodes might=20 be a good idea (as shown on page 6), but basically this chip has=20 internal clamping diodes. Note about L293: Watch out, the L293D version has such diodes, the L293=20 has not!! --=20 Wouter van Ooijen -- ------------------------------------------- Van Ooijen Technische Informatica: www.voti.nl consultancy, development, PICmicro products docent Hogeschool van Utrecht: www.voti.nl/hvu --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .