TLL Basic Usage Rules
Chapter 2 looked at the ‘74’-series of ICs and at various sub-members of its TTL and CMOS families, and explained matters such as TTL logic levels, noise immunity, and fan-in and fan-out. The present chapter continues the ‘TTL’ theme by describing TTL’s basic usage rules.
TTL Basic Usage Rules
It is usually a fairly simple matter to design logic circuitry using ‘74’-series TTL ICs, provided that a set of TTL basic usage rules are observed. Assuming that the matter of fan-in and fan-out has already been taken care of as described in Chapter 2, four other ‘basic usage’ themes remain, and these are described in the next few pages under the general headings of Power supplies, Input signals, Unused inputs, and Interfacing. ...