On Thu, 8/20/15, Mouse <mo...@rodents-montreal.org> wrote: > Maybe _rated_ current, but, even there, I don't think so (my TTL > doc hasn't been unpacked yet, or I'd go check, but I'm fairly sure > they are generally specced to sink more current to GND > than source from Vcc). It so happens I have a TTL handbook to hand at the moment. From the 1985 TI TTL data book:
Ioh Iol 7400 -0.4 16 74H00 -0.5 20 74LS00 -0.4 8 74S00 -1 20 all in mA. So as rated, TTL devices can sink a solid order of magnitude more current than they can source. BLS