> On Aug 20, 2015, at 3:40 PM, Eric Smith <space...@gmail.com> wrote: > > On Thu, Aug 20, 2015 at 10:54 AM, Paul Koning <paulkon...@comcast.net> wrote: >> Ok, but when you refer to "drive strength" I assumed you were talking about >> current, not voltage. By that measure totem pole outputs are pretty much >> symmetrical. > > Not for true (bipolar) TTL. See the specs for the 7400, 74LS00, 74S00: > http://www.ti.com/lit/ds/symlink/sn74ls00.pdf > > Ioh(max) Iol(max) > 7400 -0.4 16 > 74LS00 -0.4 8 > 74S00 -1 20 > > CMOS for comparison: > http://www.ti.com/lit/ds/symlink/sn74hct00.pdf > http://www.ti.com/lit/ds/symlink/sn74act00.pdf > > Ioh(max) Iol(max) > 74HCT00 -4 4 > 74ACT00 -24 24
Ok, clearly my memory was faulty. Thanks for the corrections. paul