Page 79 - Electrician - TT (Volume 2)

ELECTRICIAN - CITS

Integrated circuit voltage regulators

Objectives: At the end of this lesson you shall be able to
• explain integrated circuit
• state the classification of integrated circuit
• state the types of IC voltage regulators
• design voltage regulator for a required output voltage
• modify fixed voltage regulator to variable output regulator, circuit.

IC introduction
Integrated circuit

Electronic circuits invariably consist of a number of discrete components connected to each other in a specific
way. For instance, the series regulator circuit discussed in earlier lessons, consists of transistors, zener diodes,
resistors and so on, connected in a defined way for it to function as a regulator. If all these components instead
of building on a board, if they are built on a single wafer of a semiconductor crystal, then, the physical size of the
circuit becomes very small. although small, this will do the same job as that of the circuit wired using discrete
components. Such miniaturised electronic circuits produced within and upon a single crystal, usually silicon, are
known as Integrated circuits or ICs. Integrated circuits (ICs) can consists of thousands of active components
like transistor, diodes and passive components like resistors and capacitors in some specific order such that they
function in a defined way, say as voltage regulators or amplifiers or oscillators and so on.
Classification of Integrated circuits: Integrated circuits may be classified in several ways. However the most
popular classifications is as follows:
1 Based on its type of circuitry

i Analog ICs - Example: amplifier ICs, voltage regulator ICs etc.
ii Digital ICs - Example: Digital gates, flip-flops, address etc.

2 Based on the number of transistors built into IC
i Small scale integration (SSI) - consists of 1 to 10 transistors.
ii Medium scale integration (MSI) - consists of 10 to 100 transistors.

iii Large scale integration (LSI) - 100 to 1000 transistors.
iv Very large scale integration (VLSI) - 1000 and above.

3 Based on the type of transistors used
i Bipolar - carries both electron and hole current.

ii Metal oxide semiconductor (MOS) - electron or hole current.
iii Complementary metal oxide semiconductor (CMOS) - electron or hole current.
Note: The terms MOS and CMOS are another type of transistor and the trainees are requested to
refer any standard electronic book for further reference.
ICs are available in different packages and shapes. The usual packages are:

– dual in the packages DIP
– single in line package SIP and

– metal can packages.
ICs handling power more than IW are provided with heat sinks.

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CITS : Power - Electrician & Wireman - Lesson 60-69