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Power Supplies
By: Professor Wilmer Arellano
Acknowledgment
Switching Regulator (Texas Instruments)
 AN-556 Introduction to Power Supplies
 Microelectronic Circuits By: Sedra/Smith
Overview
 Important Facts
 Classification
 AC to DC Power Supplies
– Diode Rectifier
– Filter
– Voltage Regulator
 DC to DC Converters
– Buck Regulator
– Boost Regulator
– Inverting Regulator
– Other Configurations
Important Facts
 Power Supplies now comprise a
worldwide segment of the electronics
market in excess of $5 billion
annually.
 Virtually all electronic equipments
are powered by a DC power supply.
Classification
 AC/DC
 DC/DC
 DC/AC
AC to DC Power Supplies
Diode Rectifiers
Diode Rectifiers
Diode Rectifiers
Filter
Filter
Vr  V p /( fCR)
iD max  I L (1  2 2V p / Vr )
Filter
Vr  V p /( 2 fCR)
iD max  I L (1  2 2V p / Vr )
Voltage Regulator
Voltage Regulator
Vs min  VZ 0  rz I z min
R
I z min  I L max
V0
rz
Line regulation 

R  rz VS
Load regulation  (rZ // R) 
V0
I L
Voltage Regulator
Full-wave Bridge Power Supply
Center-tap Power Supply
Voltage Regulator
Adjustable Positive Regulator
Adjustable Negative Regulator
 R2 
VO  VREF  1    I ADJ  R2
 R1 
Voltage Regulator
DC to DC Converters
 This type falls under the category of switching




power supplies.
Switching is controlled by Pulse Width
Modulation.
Popular because of high efficiency and high
power density.
Obtain higher, lower, or inverting DC voltages.
Three main types of converters:
– Buck Regulator
– Boost Regulator
– Inverting Regulator
– Other Configurations
DC to DC Converters
 Buck Regulator
– The most commonly used switching
converter is the Buck, which is used to
down-convert a DC voltage to a lower DC
voltage of the same polarity.
– This is essential in systems that use
distributed power rails (like 24V to 48V),
which must be locally converted to 15V,
12V or 5V with very little power loss.
DC to DC Converters
DC to DC Converters
DC to DC Converters
 BOOST REGULATOR
– The Boost regulator takes a DC input
voltage and produces a DC output
voltage that is higher in value than the
input (but of the same polarity).
– The Boost regulator is shown in
Figure 31, along with details showing
the path of current flow during the
switch on and off time.
DC to DC Converters
DC to DC Converters
 BUCK-BOOST (INVERTING)
REGULATOR
– The Buck-Boost or Inverting regulator
takes a DC input voltage and
produces a DC output voltage that is
opposite in polarity to the input.
– The negative output voltage can be
either larger or smaller in magnitude
than the input voltage.
DC to DC Converters
DC to DC Converters
 FLYBACK REGULATOR
– The Flyback is the most versatile of all the
topologies, allowing the designer to create
one or more output voltages, some of
which may be opposite in polarity.
– Flyback converters have gained popularity
in battery-powered systems, where a
single voltage must be converted into the
required system voltages (for example,
+5V, +12V and -12V) with very high power
conversion efficiency.
DC to DC Converters
DC to DC Converters
DC to DC Converters
http://www.digikey.com/product-detail/en/NMT1272SC/811-1584-5ND/1927145
http://www.digikey.com/product-detail/en/NMT1272SC/811-1584-5ND/1927145
http://www.digikey.com/product-detail/en/NMT1272SC/811-1584-5-ND/1927145
Review
 Important Facts
 Classification
 AC to DC Power Supplies
– Diode Rectifier
– Filter
– Voltage Regulator
 DC to DC Converters
– Buck Regulator
– Boost Regulator
– Inverting Regulator
– Other Configurations
&
Questions
Answers