Choosing The Right DC Power Supply For Your
Application

The DC Power Supply is a rather fundamental electronic device,
however there are hundreds of DC Power Supply products on the
market from dozen of manufacturers. Narrowing down the best
product for your application and budget can be a daunting task.
This article addresses DC Power Supply differentiators,
functions and the applications they are best suited for. The
article's focus is DC Power Supplies used by engineers,
manufacturers, quality professionals and electronic hobbyists
for the purposes of R&D, manufacturing and testing.

Power Supplies can range in price from $50 to $20,000 and the
cost is often directly proportional to the amount of power the
device outputs. The primary function of a power supply is to
regulate output voltage and current. It takes an input power
and regulates the output power as to enforce a constant voltage
and current. In the case of DC Power Supplies, the input power
is converted from alternating current (AC) to direct current
(DC). There are two basic types of regulated DC Power Supplies:
Linear and Switching.

Linear power supplies can never output a higher voltage than
the input source. In theory, a linear power supply that is
driven by typical 110V wall outlet could only output 110V,
assuming the device were 100% efficient. Realistically, no
power supply is 100% efficient because power conversion always
results in energy loss, usually in the form of heat
dissipation. Therefore, linear power supplies usually output
voltage that is significantly less than the input.

Switching power supplies can step-up, step-down or invert the
input voltage. Switching power supplies are usually larger,
noisier and more expensive than their linear counterparts,
however, switching power supplies are typically more efficient.


Choosing the right DC power supply for your application
requires definition of some basic design specifications:
voltage range, current range, number of outputs, power
cleanliness (known as "ripple") and programmability. In
general, the higher the output voltage and the lower the
ripple, the more expensive the DC Power Supply. Multiple
outputs and programmability features will also add to the cost.


The least expensive DC Power Supplies are ideal for electronics
hobbyists and basic electro-mechanical applications where only
raw power is required. It is likely that the devices being
powered in these applications already have power-conditioning
features that eliminate the need for precision input power. Low
power, single output, DC power supplies range in price from $50
to $200.

Mid-range power supplies are best suited for non-critical,
laboratory projects involving more advanced electro-mechanical
applications or basic board-level testing. Mid-range power
supplies might have multiple outputs, higher power ratings,
lower ripple and precision, digital metering (+/- .001V, +/-
.01A). Mid-range DC power supplies can be linear or switching
and could range in price from $200 to $1,000.

High-end applications requiring high output voltage, advanced
programmability (GPIB PC Interfaces), numerous outputs and very
low ripple should budget in excess of $1,000 for their DC power
supply. Many laboratory, R&D and testing applications could
easily spend $5,000 to $10,000 per power supply.

This article has introduced some basic features and
applications of DC Power Supplies. Before making your final
purchase, be sure to consult the manufacturer and thoroughly
understand all the specifications of a particular product.
Choosing the best and most economical DC Power Supply for your
application does not have to be a complex and time-consuming
task. By identifying your design parameters, you will quickly
narrow down product selection to niche class of products from
only a few manufacturers.


About The Author: Robert Preville is the President and CEO of
Global Test Supply, LLC,(http://www.GlobalTestSupply.com) a
distributor of test and measurement equipment, and welcomes
question from those looking for a DC Power Supply.