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EEVblog 1611 - Top 5 Jellybean 7400 & 4000 Logic

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The 74xx4053 can do even more: If some glue logic is needed, it can often replace the 74xx00 NAND and 74xx02 NOR. And since design with transmission gates is less common, it is also less boring!

In fact, the transmission gate is more versatile than any other gate. In principle, any gate logic can be made from 74xx4053s only. While a pure NAND or NOR design requires anything other than NAND or NOR to be made from more than one gate (except an inverter), a single transmission gate can be wired for 6 different functions, see table below. This means a lower number of gates is required for a given task. Usually, this should also result in lesser PCB space and cost.

It is important, however, to pay attention to the effects of chaining the gates: If a signal has to pass through several stages, the propagation delay increases or it may not work at all. Intermediate inverters, whether made from transmission or other gates, will fix this.

Y0, Y1 = MPX inputs
S = select input
Z = MPX output

A, B, C = inputs of logic function

Y0      Y1      S       Z = logic function
0       1       A       buffer A
1       0       A       not A
B       1       A       A or B
0       B       A       A and B

B       0       A       ~A and B
1       B       A       ~A or B

Bonus, the general 3-input function:

B       C       A       (A and C) or (~A and B)

1. List of 7400-series integrated circuits

2. List of 4000-series integrated circuits

Have fun...   ;D


--- Quote from: Nominal Animal on April 20, 2024, 03:17:15 pm ---I see so many posts and reports of hobbyists like me burning their microcontrollers or SBCs or at least a few I/O pins on them, by not thinking about this stuff at all.  I wish someone with a wide enough viewership would point this out, because the solutions are so easy and easily available.  Starting from the current-limiting resistor (which relies on the ESD or other diodes to voltage rails), to transistor open collector outputs with pull-up resistors, to level translating transceivers, to digital isolators.
--- End quote ---

74ls07, buffer, open-collector, very useful for translating voltages.


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