Page 80 - Electrician - TT (Volume 2)
P. 80

ELECTRICIAN - CITS



           Advantages of integrated circuits over discrete circuit (Refer Table 1)
                                                         Table 1

                                         Integrated circuits     Discrete circuits


                                      1  All in a single chip   All are separate discrete
                                                              components

                                      2  Requires less space    Requires more space
                                        due to smaller size
                                      3  Cheaper due to mass   Costlier due to individual
                                       manufacture            components
                                      4  More reliable due to   Less reliable
                                        specific construction
                                      5  Easy for servicing and  Difficult for servicing and
                                       repairs                repairs


                                      1  ICs are manufactured   Discrete devices can be
                                        for specific applications  used for any circuit
                                        having specific circuits
                                      2  If any part of IC is   Only particular defective
                                        defective, the entire   component requires
                                        IC is to be replaced   replacement


           When the advantages are considered, the disadvantages of IC are negligible.  They are widely used for different
           applications such as voltage regulators, audio amplifiers, TV circuits, computers, industrial amplifiers etc. ICs are
           available in different pin configurations in different outlines suitable for different circuits.
           Integrated circuit (IC) voltage regulators: The series voltage regulators discussed in earlier lessons are available
           in the form of integrated circuits (ICs).  They are known as voltage regulator ICs.
           There are two types of voltage regulator ICs.  They are,
           –  Fixed output voltage regulator ICs
           –  Adjustable output voltage regulator ICs.
           Fixed output voltage regulator ICs: The latest generation of fixed output voltage regulator ICs have only three pins
           as  in Fig 1. They are designed to provide either positive or negative regulated DC output voltage.
           These ICs consist of all those components and even more in the small packages in Fig 1.  These ICs, when used
           as voltage regulators, do not need extra components other than two small value capacitors as in Fig 2.
           The reason behind using capacitor C1 is when the voltage regulator IC is more than a few inches from the filter
           capacitors of the unregulated power supply, the lead inductance may produce oscillations within the IC.  Capacitor
           C1 prevents setting up of such oscillations.  Typical value of bypass capacitor C1 range from 0.220µF to 1µF.  It
           is important to note that C1 should be connected as close to the IC as possible.

           The capacitor C2 is used to improve the transient response of the regulated output voltage.  C2  bypasses these
           transients produced during the ON/OFF time.  Typical values of C2 range from 0.1µF to 10µF.
           Fixed voltage three terminal regulators are available from different IC manufacturers for different output voltages
           (such as 5V, 9v, 12V, 24V) with maximum load current rating ranging from 100mA to more than three amps.









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