Mini-ITX Power Solutions Andrei Bulucea
Automotive Solutions Ituner Networks
DC-DC converters - 5 - Automotive Applications
Power Requirements for Small Computer Design
Along with availability of low-power processors and main boards, one of the main challenges of
building a small computer is peripheral size and power consumption. The computer industry has
provided many solutions in the storage arena such as miniature 2.5” Hard Drives, Slim-CD
CDROMs and DVDROMS and lately Compact Flash disk storage solutions used to store
operating systems and content. For more information on Compact flash adapters, please see the
final portion of this article.
NOTE: If you are planning to develop a car PC application, use 2.5” disk drives, as they are rated
for greater shock protection and lower power consumption. While the cost per MB on a 3.5” might
seem appealing, keep in mind that 3.5” drives are not designed for mobile applications.
Peripherals Power Facts
Q) How much power does a 7200 RMP drive needs?
A) A 7200 RPM drive consumes 10-15 W, mostly from the 12 V rail. A 5400 RMP drive consumes less.
Please refer to the manufacturer product spec for detailed power consumption charts. If you plan on using
multiple 3.5" drives, use the PW-60a and the PW-70a dc-dc converters. See more information below.
Q) How much power does a laptop drive consume?
A) Peak power consumption is only 5 W with an average power consumption of 2.5 W. All dc-dc adapters
can handle laptop drives.
Q) How about CD-ROMS and DVD-ROMS and slim-CDs?
A) Depending on CD-ROM type, your unit can consume anywhere between 5 and 20 W. Very fast
CDROMS (48X) tend to draw a lot of power from the
12 V rail at spin-up time. Slim-CDs consume an
average of 5 W. When not in use, the power consumption drops to 0.1 W.
Q) How about USB devices?
A) Usually USB devices consume 5 W or less by design. If more power is required by the device, an
external adaptor is used.
Q) What is the power consumption of a CF disk?
A) Less than 0.5 W! CF disk are ideal for embedded applications. See the “Compact Flash to IDE” section of
this article for more information on Compact Flashes.
Q) What is the power consumption of an 2x20 or 2x16 LCD display?
A) Depending on model and type, the power consumption is less than 2.5 W. Larger LCD displays tend to
consume more power.
PSU, the Ultimate Challenge for Small PCs
While hard drives, CDROMS and Flash storage units are getting smaller, power supplies seem to
lag behind in the small footprint race. Higher power required by faster processors have driven the
power supply industry into a race for bigger and more powerful solutions.
With the introduction of the mini-ITX platform, the power requirements have dropped, but the
power supply size remained the same. Fig 1.3 shows a typical ATX power supply with
dimensions of W150 x H86 x D140 (mm). As you can see, this power supply is almost as big as
the mini-ITX board!
(55 paginas)
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