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