This document presents an overview of integrated circuit voltage regulators. It discusses the need for voltage regulation in circuits to maintain stable potentials. Different types of voltage regulators are described, including fixed output regulators like the 78XX and 79XX series, adjustable output regulators like the LM317, and switching regulators like the MC1723. Key parameters that define regulator performance are also outlined. The document then provides more detailed explanations of specific voltage regulator ICs, their applications, connections, and characteristics.

1. A
Presentation on
IC VOLTAGE REGULATORS
submitted in partial fulfillment for the award of the degree of
Bachelor Of Technology
(Rajasthan Technical University, Kota) Submitted
by:- Gajendra Singh
8th sem ECE
Submitted to:- Sanjay Kumar Singhal
Head Of Department

2. INTRODUCTION
Voltage regulator :-
It is a circuit that supplies constant
voltage regardless of changes in the load current.

3. Need for regulation
Without stable potentials, circuit performance degrades
and if the variations are large enough the components
may get destroyed.
 In order to avoid this problem regulation is used.

4. Basic power supply
 Transformer: Steps down high
voltage AC mains to low voltage
AC.
 Rectifier:converts AC to DC,
but the DC output is varying.
 Filter: smooth the DC from
varying greatly to a small ripple.
 Regulator : Eliminates ripple by
setting DC output to a fixed
voltage.

5. IC Voltage Regulators
Advantages of IC voltage regulator
 Inexpensive
 Versatile
 Provides current /voltage boosting
 Internal short circuit current limiting

6. Classification of IC voltage regulators:
There are basically two kinds of IC voltage regulators:
Multi-pin type, e.g. LM723C
3-pin type, e.g. 78/79XX
Multi-pin regulators are less popular but they provide
the greatest flexibility and produce the highest quality
voltage regulation.
3-pin types make regulator circuit design simple

7. Types of IC voltage regulators:
1. Fixed output voltage regulators: Positive fixed output
regulator(78XX series) and negative fixed output regulator(79XX series).
2. Adjustable output voltage regulators: Positive (LM317) and
negative(LM337).
3. Switching regulators: Motorola ‘s MC1723.
NOTE: MC1723 is a general purpose regulator ;it can be used in many
ways as a fixed positive or negative output voltage regulator, variable
output voltage regulator or as a switching regulator. Due to its flexibility it
has become as a standard type in the electronics industry.

8. Topics to be dealt
• 78XX series
• 79XX series
• 317 variable regulators
• 1723 switching regulators

9. Performance parameters of voltage regulators
 Line or input regulation: Defined as a change in output voltage for a
change in input voltage.
 Load regulation: Defined as the change in output voltage for a change in
load current.
 Temperature stability or average temperature coefficient of output
voltage(TCVO): Defined as the change in output voltage per unit change in
temperature and expressed in millivolts per degree Celsius.
 Ripple rejection: It is the measure of regulator’s ability to reject ripple
voltages. It is usually expressed in decibels.
The smaller the value of these performance parameters ,the better the regulator.

10. FIXED VOLTAGE REGULATOR
a)Positive voltage regulator
• The 78XX voltage regulators
• Fig shows the connection diagram of 78XX series
• Proper operation requires a common ground between the input and output
voltages.

11. 78XX basic features
IC No Voltage
7805 5V
7806 6V
7808 8V
7809 9V
7810 10V
7812 12V
7815 15V
7818 18V
7824 24V
• Features
• 3 terminal positive voltage
regulator with nine voltage
options
• High Output Current - typically
1.5A
• Short circuit current limit -
750mA at 5v
• Max input voltage = 35v
• Minimum Input Voltage = Vout +
2.5

12. 7805 as current source
 The 7805 regulators can also be employed as current
sources. A typical connection diagram of 7805 IC as a 0.5 A
current source is depicted in figure.

13. b)Negative voltage regulators
• Negative voltage regulator IC's are available in
79XX series.
• These IC's are similar to the 78 series, but
operating on negative voltage, and providing a
regulated negative output voltage.
• The capacitors connected at the input and output
sides are used to provide additional filter circuits
of regulator circuits.

14. Features of 79XX
IC No Voltage
7902 -2V
7905 -5V
7905.5 -5.2V
7906 -6.2V
7908 -8V
7912 -12V
7915 -15V
7918 -18V
7924 -24V
• Same as that of
78XX series except
that 79XX series are
negative regulators
• They are available in
same seven voltage
options with two
extra voltage
options,-2V and -
5.2V.

15. ADJUSTABLE VOLTAGE REGULATOR
Adjustable voltage regulators are those who voltage
can be varied and utilized.
Advantages of adjustable voltage regulators
 Improved system performance
 Improved overload protection
 Improved system reliability
Example: LM317

16. 1) Positive Adjustable Voltage Regulators-
LM317
• The LM317 is a three terminal positive voltage
regulator, which can be operated with the output
voltage regulated at any setting over the range
of 1.2 V to 57 V.
• The three terminals are Vin. Vout and
Adjustment(adj).

17. 2) Negative Adjustable Voltage Regulators-
LM337
• The LM337 series of voltage regulators are a
complement of LM317 series.
• They are negative adjustable voltage regulators
• These negative voltage regulators are available in the
same voltage and current options as the positive
adjustable voltage regulator LM317.

18. Switching Regulator
• In switching regulator, the transistor acts as a
switch.
• When the transistor is off(switch is open), no
current flows, therefore no power dissipation.
• When the transistor is on,(switch is closed),
high current flows but Vce becomes low and
therefore power dissipation is less.

19. Features
MC1723
• Delivers load current of about 150mA without an external
pass transistor.
• Output voltage range 3Vdc to 37 Vdc.
• It is a general purpose regulator and can be used as fixed
variable and switching regulator.
• The regulator requires an external transistor and a 1mh choke.
• To minimize its power dissipation during switching, external
transistor used must be switching power transistor.