There are several other factors that affect decoupling: PCB Layout (smaller is better) Ground planes size, distance between ground planes and dielectric material used Decoupling cap ESR Proximity of the decoupling caps to the power pins Number and size of vias connected to power pins (think of vias as a small inductor) Copper pour profile used to connect power pins to power rail
Clearly the BBB layout is optimal and that is why they managed to make the board work with fewer decoupling caps. Regards, John > On May 26, 2016, at 8:52 AM, Gerald Coley <[email protected]> wrote: > > Same answer as before. > > BeagleBone came first. > Smaller board size. > Lower cost > And it works. > > Gerald > > On Thu, May 26, 2016 at 10:46 AM, <[email protected] > <mailto:[email protected]>> wrote: > I see difference between last schematic of beaglebone black and am3358 > starter kit board concerning vdds_ddr decoupling cap. Am3358 sk board has 21 > decoupling cap and beaglebone black uses 9 decoupling caps. The am3358 > datasheet specifies tu use min 20 decoupling caps. Why this difference? > > -- > For more options, visit http://beagleboard.org/discuss > <http://beagleboard.org/discuss> > --- > You received this message because you are subscribed to the Google Groups > "BeagleBoard" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected] > <mailto:beagleboard%[email protected]>. > To view this discussion on the web visit > https://groups.google.com/d/msgid/beagleboard/b282b991-9043-4f98-8626-44bc5acb4de6%40googlegroups.com > > <https://groups.google.com/d/msgid/beagleboard/b282b991-9043-4f98-8626-44bc5acb4de6%40googlegroups.com>. > For more options, visit https://groups.google.com/d/optout > <https://groups.google.com/d/optout>. > > > > -- > Gerald > > [email protected] <mailto:[email protected]> > http://beagleboard.org/ <http://beagleboard.org/> > [email protected] <mailto:[email protected]> > > > -- > For more options, visit http://beagleboard.org/discuss > <http://beagleboard.org/discuss> > --- > You received this message because you are subscribed to the Google Groups > "BeagleBoard" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected] > <mailto:[email protected]>. > To view this discussion on the web visit > https://groups.google.com/d/msgid/beagleboard/CAHK_S%2BcKFuME82TcQfgtafO-63ZXVDNERAAcs8qmGs1q-doWqQ%40mail.gmail.com > > <https://groups.google.com/d/msgid/beagleboard/CAHK_S%2BcKFuME82TcQfgtafO-63ZXVDNERAAcs8qmGs1q-doWqQ%40mail.gmail.com?utm_medium=email&utm_source=footer>. > For more options, visit https://groups.google.com/d/optout > <https://groups.google.com/d/optout>. -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/25F7FBF8-99E0-41D9-88B0-30F598A4C80E%40gmail.com. For more options, visit https://groups.google.com/d/optout.
