I am regularly sending ordinary people to look a the application sections of the datasheets for several electronic parts if they want to know how a part should be used. As I was laying out the motor boards for the weekends workshop I came across the following in the datasheet for the L239(not d) clone that Texas Intruments puts out.
Can you tell where the chip begins and the diagram ends? Can you tell that the diodes are (not really) included in the chip or would you add them to your parts count.?
I nearly panicked and relayed out everything with 8 general purpose diodes and ordered the parts before I was able to ascertain (incorrectly) that the diodes in the diagram above are actually integrated into the chip.
ladyada
The diodes in the app diagram are NOT integrated in the chip
The chip is -not- a L293D replacement, it is a L293 replacement
http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1200888334/30
http://www.ladyada.net/make/mshield/use.html
I spoke directly with TI engineers regarding this matter. Using the internal ESD protection diodes as clamp diodes is not recommended but you can ‘get away with it’ if you’re not doing a production design
feurig
Its like a visitation from a patron saint or something.
As usual my choice of parts has to do with trying to make 20 of something to share and since I already threw down for the servos the much more expensive L293D was not in the works.
As for the lack of external diodes we will have to “get away with it” mostly ‘because while I was able to get another 8 parts in the same foot print I am not going to be able to get the diodes here in time for Sunday s workshop. The board design really is for the L293D.
The code samples in the links above will definitely make it into the curriculum.
feurig