On Feb 8, 2011, at 14:48:14, Joerg Wunsch wrote: > Ruud Vlaming <[email protected]> wrote: > >> i cannot find the datasheet of the 644A, so i have no >> real comparrisson at the moment. > > I don't think there is any ATmega644A, it's probably only available as > an ATmega644PA.
There definitely is, I have several in DIP 40, and ordered some in TQFP. > The ATmega644 vs. ATmega644P is IMHO the only time where the suffix > letter actually indicated two different feature sets (with/without > second USART). The data sheet I have references the following: ATmega164A ATmega164PA ATmega324A ATmega324PA ATmega644A ATmega644PA ATmega1284 ATmega1284P Near as I can tell, they all have dual USARTs (that was a requirement for my design). > The "A" devices are die-shrink versions, where all the connections > have been routed with smaller traces, yet retaining the original > transistor structure sizes (to avoid different electrical behaviour > compared to the non-A versions). This leads to somewhat faster ICs, > so the original distinction between two speed vs. voltage device > classes (L/V devices vs. devices without that suffix) became obsolete > with the A devices. Thanks for the explanation about "A". I sure wish they'd have a simple table in each data sheet that covers multiple products indicating quickly what aspects are different, and perhaps referencing more detailed differences elsewhere. -- Rick _______________________________________________ AVR-chat mailing list [email protected] http://lists.nongnu.org/mailman/listinfo/avr-chat
