foperator@tekno.chalmers.se (Daniel Berglund) (06/08/89)
Is it possible for an NMOS device (in this case, a 68000) to utilize CMOS (74HCxx) interface circuits? The data sheets say that Voh from the 68000 is _at least_ 2.4 V (and at most Vcc), but an HC device wants at least 3.15 V to be happy (@Vcc=5V). Can I safely assume that the 68000 lines, if connected to "only a few" HC inputs (and no power-eating LS-TTLs), will be able to pull the voltage level up to a value acceptable by the HC circuits? Or do I have to resort to HCT devices? I don't like the idea of adding another dozen of chips just for the sake of level-shifting. It would be much easier if those HCT devices came in all flavours and not just in the buffer-and-latch-related ones.. (actually, they seem to be _fabricated_ but not _sold_, at least not by the dealers I usually use) Similary, would an LS - or better ALS - device pull up to CMOS levels when connected to only one or two HC inputs? -- Daniel Berglund (foperator@tekno.chalmers.se, BITNET: FOP@SECTHF51) Chalmers University of Technology, G|teborg, Sweden
abali@parts.eng.ohio-state.edu (Bulent Abali) (06/08/89)
In article <811@tekno.chalmers.se> foperator@tekno.chalmers.se (Daniel Berglund) writes: >Is it possible for an NMOS device (in this case, a 68000) to utilize CMOS >(74HCxx) interface circuits? The data sheets say that Voh from the 68000 is >_at least_ 2.4 V (and at most Vcc), but an HC device wants at least 3.15 V to be >happy (@Vcc=5V). Connect a pullup resistor between 68000 output and Vcc. Resistor must be large enough so that I_OL current rating of 68000 output is not exceeded (1K-4.7K may do it). -=- Bulent Abali Ohio State Univ., Dept.of Electrical Eng. 2015 Neil Av. Columbus, Ohio 43210 abali@baloo.eng.ohio-state.edu