Understanding The Switch Mode Power Supply Better

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Understanding the Switch Mode Power Supply
Better Miracle Electronics
The most important element of an electronic
circuit is the power supply that provides current
to the entire circuit. Different circuits
require different kinds of power of different
ranges. This is why different power converters
are used to change the power into the range that
is required by the individual application it is
applied to. This is where the Switch Mode Power
Supply (SMPS) comes in handy, which is an
electronic circuit that converts power using
switching devices and inductors or capacitors to
change the electrical power from one form to
another as required. The power supply is
generally used to achieve regulated DC output
voltage from DC input voltage or unregulated AC.
How does SMPS work? SMPS consists of a switching
regulator that manages the regulation in the
unit. This switching element switches the
current supply to a smoothing capacitor on and
off. The voltage on the capacitor controls the
time that the series element is switched. It is
the continuous switching of the capacitor that
maintains its voltage at the required level. The
AC power first passes through
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the fuses and a line filter, which is then
rectified by a full-wave bridge rectifier. This
rectified voltage is then applied to the power
factor correction pre-regulator, which is then
followed by a DC-DC convertor. What are the
different types of SMPS available? DC-DC
CONVERTER In a DC-DC converter, the power that
is received from the AC main is rectified and
filtered as high voltage DC, which is then
switched at a huge rate of speed and fed into
the primary of the step-down transformer. The
filtered and rectified output is then received
at the secondary of the transformer, which is
further sent to the output of the power supply.
Some of this output is sent back to the switch to
control output voltage. FORWARD CONVERTER In a
forward converter, the diode carries the current
during the Off stage of the transistor. This
is why energy flows into the load in the On
stage as well as off stage too and this current
is carried by the choke. It stores energy during
the On stage and also transfers some of it
into the output load. FLYBACK CONVERTER In a
fly-back converter, the magnetic field of the
inductor stores energy during the On period of
the switch, which is then emptied into the output
voltage circuit when the switch is open. This
duty cycle decides upon the output voltage of the
circuit. SELF-OSCILLATING FLYBACK CONVERTER
This is the simplest and most basic converter
wherein the current that flows through the
transformer primary starts rising continuously
with the slope during the conduction time of the
switching transistor. And, when this current
reaches its peak, the core begins to
saturate. What are the pros and cons of
SMPS? As compared to linear regulators, the SMPS
is much more efficient with lesser standby power
loss and smaller size with light weight, along
with being much more cost-effective. However,
the SMPS is more complex than linear regulators,
and it generates higher amplitude, frequency,
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harmonic frequency, and ripple voltage. Also, it
pairs electrical switching noise back onto the
main power line, thus causing interference with
equipment connected to the similar phase. For
getting your hands on the best quality SMPS to be
used in machine tool productions, security
systems, AV products, support supplies for PLCs,
or any other relevant application, you can
approach Miracle Electronics, the leading SMPS
transformer manufacturer in India. You can get
high power-to-size ratio SMPS transformers that
are RoHS compliant and high reach compliant to
achieve minimal power wastage. For more
details, visit Miracle Electronics