Electronics is growing rapidly. One major
reason is the advance in performance while costs
remain stable and sometimes decrease. Circuits
have become a lot smaller, more reliable, and
more energy efficient. Witness the many
portable devices available today. Integrated circuit technology is the major force behind the
growth in the electronics industry. Consider that
many systems and devices that we now enjoy
were not practical or even possible a decade ago.
Discrete circuits use individual resistors, capacitors, diodes, transistors, and other devices
to achieve the circuit function. These individual
or discrete parts must be interconnected. The
usual approach is to use a circuit board. This
method, however, increases the cost of the circuit.
The board, assembly, soldering, and testing all
make up a part of the cost.
Integrated circuits do not eliminate the need
for circuit boards, assembly, soldering, and testing. However, with ICs the number of discrete
parts can be reduced. This means that the circuit
boards can be smaller, often use less power, and that they will cost less to produce. It may also be
possible to reduce the overall size of the equipment by using integrated circuits, which can
reduce costs in the chassis and cabinet.
Integrated circuits may lead to circuits that
require fewer alignment steps at the factory.
This is especially true with digital devices.
Alignment is expensive, and fewer steps mean
lower costs. Also, variable components are
more expensive than fixed components, and if
some components can be eliminated, savings
are realized. Finally, variable components are
not as reliable as fixed components.Integrated circuits may also increase performance. Certain ICs work better than equivalent
discrete circuits. A good example is a modern
integrated voltage regulator. A typical unit may
offer 0.03 percent regulation, excellent ripple and
noise suppression, automatic current limiting,
and thermal shutdown. An equivalent discrete
regulator may contain dozens of parts, cost six
times as much, and still not work as well Reliability is related indirectly to the number
of parts in the equipment. As the number of
parts goes up, the reliability comes down. Integrated circuits make it possible to reduce the
number of discrete parts in a piece of equipment. Thus, electronic equipment can be made
more reliable by the use of more ICs and fewer
discrete components.
Integrated circuits are available in an in creasing number of package styles. Figure 13-1shows some of them. At one time, the dual
in-line package (DIP) was very popular and
lent itself to insertion into sockets or insertion
into holes in printed circuit boards. Now,
most boards use surface mount technology
and sockets are almost a thing of the past.
A few integrated circuits, such as voltage
regulators, use 3-leaded packages such as the
TO-220 (Fig. 5-17), which is also used for
some power transistors. Thus, one cannot
always properly identify a component with a
casual glance. Service literature and part
numbers are a must.