This document provides information about an active learning assignment on integrated circuit (IC) voltage regulators and fixed voltage regulators presented by three electrical engineering students. It discusses different types of voltage regulators including IC voltage regulators, features of IC voltage regulators, classification of IC voltage regulators into linear and switching regulators. It provides details about linear regulators and switching regulators. It also describes three-terminal fixed voltage regulators including the 78XX and 79XX series and their output voltages. The block diagram of a three-terminal IC voltage regulator is explained.

1. Active Learning Assignment
Subject : Analog Electronics.
Topic : IC voltage regulator and fixed voltage regulator.
Branch : Electrical Engineering.
Division : B-1
Presented By : Aniruddh Joshi(140120109001)
Dheeraj Yadav(140120109010)
Chandresh Jiyani(140120109013)
Guided By : Prof. Pratik Gohel.
Gandhinagar Institute of Technology

2. VOLTAGE REGULATOR
A voltage regulator is designed to automatically maintain a constant
voltage level. A voltage regulator may be simple “ feed forward” design or
may include negative feedback control loops. It may use an
electromechanical mechanism, or electronic components. Depending on
the design, it may be used to regulate one or more AC or DC voltages.

3. IC VOLTAGE REGULATOR
IC voltage regulator means integrated circuit voltage regulator. They are
basically series regulator with all the basic blocks present inside integrated
circuit. IC voltage regulators are easy to use and easy to operate.
IC voltage regulators are three-terminal devices that provide a constant DC
output voltage that is independent of the input voltage, output load current,
and temperature.

4. FEATURES OF IC VOLTAGE REGULATOR
 Programmable outputs.
 Facility to boost the voltage/current.
 Internally provided short circuit current limiting.
 Thermal shut down.
 Floating operation to facilitate higher voltage output.
 Versatility and low cost.

5. CLASSIFICATION OF IC VOLTAGE REGULATOR
IC voltage regulator : Liner regulator.
: Switching regulators.

6. LINEAR REGULATORS
 A linear regulator is a system used to maintain a steady voltage.
The resistance of the regulator varies in accordance with the load
resulting in a constant output voltage.
 In linear regulators, a series pass transducer is used. The
impedance f this transistor is continuously changed to supply the
desired load current.
 The series pass transistor always operates in its active region.
 The linear IC regulator are either fixed voltage regulator ICs(78XX
series or 79XX series) or they are variable voltage regulator ICs
such as LM 317 or LM 337.

7. SWITCHING REGULATORS
 Switching regulators are basically series type regulators with the
series transistor operating as a switch.
 Due to this power dissipation of the transistor is reduced and the
efficiency of the regulator is increased.
 This type regulator is ideal for high current applications since less
power is dissipated
 With switching regulators 90% efficiencies can be achieved.

8. Advantages of IC regulator
 The power supply design becomes easy and quick.
 The IC regulator are cheap and are easily available.
 IC regulators are small hence they reduce the size of the power supply.
 They are easy to use.
 IC regulators are versatile.
 They have features such as programmable output, facility to boost the
Out put voltage or current, internal protection such as thermal shut
down, floating operation to facilitate out put voltage etc.

9. Classification of three terminal IC voltage regulator
The three terminal IC voltage regulators are classified in to following categories.
 Fixed voltage regulator (positive and/or negative output).
 Adjustable output voltage regulator (positive and/or negative output).
The fixed voltage regulator and the adjustable voltage regulator ICs are 3-pin ICs.
Therefore they are called three pin voltage regulator ICs.

10. Block diagram of three terminal IC voltage regulator
The block diagram is basically a series voltage regulator.

11.  The resistor R2 & R1 from the sampling network to produce the feed back signal
proportional to the output voltage.
 Vref is internally generated voltage reference. This voltage reference is compared
with the feed back signal by the comparator, to produce the control signal.
 This control signal is routed through the thermal shut down and current limiting
block to the series pass transistor.
 The thermal shut down and current limiting block provides the protection
increased internal temperature or over current.
 If the internal temp. exceeds a predetermined value, then thermal shut down
block will not allow the control signal to pass through to the series pass transistor.
 This will turn off the chip automatically. The current limiting circuit protects the
regulator against over current.

12. Three terminal fixed voltage regulator
 In the fixed voltage regulator category we have positive voltage regulator and
negative output voltage regulator
 The μA 78XX series is a series of fixed voltage regulators and μA 79XX is the
fixed negative voltage regulator.

13. 78XX series (fixed positive voltage regulator)
 78XX series are three terminal, positive fixed voltage regulator. Hence XX
indicate the output voltage.
 These regulators are available in seven different output voltage option, such as
5,6,8,12,15,18 and 24.
 Thus if we select a regulator IC numbered ‘7812’, it provides us a 12 V regulated
output voltage.
IC No. 7805 7806 7808 7812 7818 7824
O/P voltage 5V 6V 8V 12V 18V 24V

14. 79XX series (fixed negative voltage regulator)
 79XX series is also available in three pin fixed voltage category. This series or
regulator Ics has designed to provide a fixed negative output voltage.
 These ICs can provide -5,-6,-8,-12,-15,-18 & -24 output voltage like 78XX series.
 Thus if we select a regulator IC numbered ‘7812’, it provides us a -12 V regulated
output voltage.
IC No. 7905 7906 7908 7912 7918 7924
O/P voltage -5V -6V -8V -12V -18V -24V

15. THANK YOU