Tab Electronics Guide to Understanding Electricity ... - Sciences Club

326 Chapter Twelve
Most ICs are manufactured as general-purpose building blocks within
a specific functional area. For example, the common 741 operational
amplifier is designed specifically for amplification type functions, but
its external component design can modify its performance for literally
thousands of different applications. In contrast, many ICs are manufactured
for very specific applications, especially in the consumer electronics
field. For example, an IC specified for use as a rotational speed
control for VCR heads can be used for little else.
It is easy to integrate semiconductor components (or components that
can be made from semiconductor materials). Very large-scale integration
(VLSI) chips can contain as many as 250,000 transistors. Resistors can be
made very accurately from semiconductor material. However, large-value
“reactive” components, such as inductors and capacitors, cannot be
reduced in size. Also, semiconductor components designed to dissipate
large quantities of power cannot be integrated very successfully. For
these reasons, many ICs are nothing more than the total low-power
semiconductor part of a larger circuit. The reactive and high-power
components must be added for a functioning circuit. “Switching regulator
control” ICs are a good example of this kind of design.
Because of the vast number of integrated circuits available, it is absolutely
necessary to have a good selection of manufacturers’ data books in your
electronics library. You will have to depend on these data books to obtain
pin-out diagrams (illustrations of the functional aspects of each connection
lead on an IC), application information, and functional specifications.
ICs can be divided into two main families: digital and linear (or analog).
Digital ICs will be discussed in the next chapter, so in this chapter,
we will concentrate primarily on linear devices.
Linear ICs can be further subdivided into several classifications:
operational amplifiers, audio amplifiers, voltage regulators, and specialpurpose
devices.
For very common applications, a manufacturer may build a complete
circuit, using ICs and discrete components, and encapsulate the complete
circuit into a block. These devices are called hybrid modules. Common
hybrid modules include high-power audio amplifiers, power supply regulators,
motor controls, and certain types of high-power, high-voltage devices.
Operational Amplifiers
Operational amplifiers are basic amplification building blocks. They consist
of multiple high-gain differential amplifiers (exhibiting high com-