intvnut Posted August 8, 2014 Share Posted August 8, 2014 (edited) M2L or not...it's working That's good. :-) The thing that always concerns me with diode-resistor logic like that is that the PN drop of a typical diode is rather close to the VIL(max) of a TTL gate. Something like 0.6v to 0.7V for a diode and 0.7 to 0.8V for VIL(max). That basically gives you no noise margin. That shouldn't be surprising since both diodes and bipolar transistors are built out of PN junctions. Now, with Schottky diodes, the drop is much lower (0.1V to 0.45V typically), and with CMOS inputs VIL(max) is usually higher, so you actually do get some noise margin.. The main point is that you have to be careful when using it if you want to build something reliable. Edited August 8, 2014 by intvnut Quote Link to comment Share on other sites More sharing options...
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