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Application Report
SLVA700–April 2015
Introduction to Logic
RyanLand
ABSTRACT
Logic circuits are the building blocks of the digital world. Computers and electronics use 1s and 0s (bits) to
transfer data. In the physical world, the 1s and 0s are represented by voltages on a wire, on microscopic
traces within an integrated circuit, or on a copper printed circuit board (PCB) trace. Computers perform
calculations and store data by using combinational and sequential logic circuits. There are many different
types of logic circuits that will be described in this report, including logic gates, registers, flip-flops, and
more. These devices receive the 1s and 0s as voltages on their inputs, and they perform specific
operations on those signals to produce an output. When used in the proper sequence, these devices can
manipulate the signals in such a way that can result in anything from a simple adding circuit to a fully-
functional supercomputer.
TI makes microcontroller units, which contain millions of small logic circuits used to perform complex
operations. However, TI also makes the individual building blocks as integrated circuits (ICs) that
engineers can use to build smaller-scale digital logic into their own systems. These individual building
blocks can also be used for voltage translation or signal conditioning.
Contents
1 Combinational Logic Gates................................................................................................. 1
2 Sequential Logic ............................................................................................................. 3
3 What are 1 and 0 in the Real World? ..................................................................................... 5
4 Logic Families................................................................................................................ 6
5 Additional Technical Reading .............................................................................................. 7
List of Figures
1 Combinational Logic Gates and their Functions......................................................................... 2
2 D-Type Flip-Flop ............................................................................................................. 3
3 J-K Flip-Flop.................................................................................................................. 4
4 Common Switching Input and Output Levels ............................................................................ 5
5 Typical V
OH
/I
OH
Relationship for Logic Circuits ........................................................................... 6
6 Typical V
OL
/I
OL
Relationship for Logic Circuits............................................................................ 6
List of Tables
1 Combinational Logic Gates
Combinational logic gates, or simply "logic gates", are the simplest type of logic circuits. They produce an
output that is either 1 (high) or 0 (low) depending in the states of one or more of their inputs. In other
words, they perform the basic functions of Boolean algebra. Logic gates are the building blocks for more
complicated logic.
Figure 1 describes each type of logic gate.
1
SLVA700–April 2015 Introduction to Logic
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