Advance Data Sheet: Dualeta™ i QA Series – Dual Quarter Brick ©2002-2005 TDK Innoveta Inc.
iQAFullDatasheet080505 2.doc 8/3/2006 ℡
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877
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498-0099 14/19
Thermal Management: An important part of the overall system
design process is thermal management;
thermal design must be considered at all
levels to ensure good reliability and lifetim e
of the final system. Superior thermal design
and ability to operate in severe application
environments are key elements of a robust,
reliable power module.
A finite amount of heat must be dissipated
from the power module to the surrounding
environment. This heat is transferred by the
three modes of heat transfer: convection,
conduction and radiation. While all three
modes of heat transfer are present in every
application, convection is the dominant
mode of heat transfer in most applications.
However, to ensure adequate cooling and
proper operation, all three modes should be
considered in a final system configuration.
The open frame design of the power module
provides an air path to individual
components. This air path improves heat
conduction and convection to the
surrounding environment, which reduces
areas of heat concentration and resulting hot
spots.
Test Setup
The thermal performance data of the power
module is based upon measurements
obtained from a wind tunnel test with the
setup shown below. This thermal test setup
replicates the typical thermal environments
encountered in most modern electronic
systems with distributed power
architectures. The electronic equipment in
optical networking, telecom, wireless and
advanced computer systems operate in
similar environments and utilize vertically
mounted PCBs or circuit cards in cabinet
racks.
The power module, as shown in the figure,
is mounted on a printed circuit board (PCB)
and is vertically oriented within the wind
tunnel. The cross section of the airflow
passage is rectangular. The spacing
between the top of the module or heatsink
(where applicable) and a parallel facing PCB
is kept at a constant (0.5 in). The power
module orientation with respect to the airflow
direction can have a significant impact on
the module’s thermal performance.
Thermal Derating:
For proper application of the power module
in a given thermal environment, output
current derating curves are provided as a
design guideline in the
AIRFLOW
A
ir Velocity and Ambient
Temperature Measurement
Location
A
I
R
F
L
O
W
12.7
(0.50)
Module
Centerline
A
ir Passage
Centerline
Adjacent PCB
76 (3.0)
Wind Tunnel Test Setup
Dimensions are in millimeters and (inches).
Thermal Performance section. The module
temperature should be measured in the final
system configuration to ensure proper
thermal management of the power module.
In all conditions, the power module should
be operated below the maximum operating
temperature shown on the de-rating curve.
For improved design margins and enhanced
system reliability, the power module may be
operated at temperatures below the
maximum rated operating temperature.
Heat transfer by convection can be
enhanced by increasing the airflow rate that
the power module experiences. The
maximum output current of the power
module is a function of ambient temperature
(TAMB) and airflow rate as shown in the