QHW100G1 Lineage Power, QHW100G1 Datasheet - Page 16

• Manufacturer Part Number: QHW100G1
• Manufacturer: Lineage Power

dc-dc Converters: 36 to 75 Vdc Input, 2.5 Vdc Output; 25 W to 50 W
Thermal Considerations
Heat Transfer with Heat Sinks
Then solve the following equation:
Use Figure 28 to determine air velocity for the 1/4 inch
heat sink.
The minimum airflow necessary for this module is
0.8 m/s (180 ft./min.).
Custom Heat Sinks
A more detailed model can be used to determine the
required thermal resistance of a heat sink to provide
necessary cooling. The total module resistance can be
separated into a resistance from case-to-sink (θcs) and
sink-to-ambient (θsa) as shown in Figure 34.
Figure 34. Resistance from Case-to-Sink and
16
16
θ
θ
θ
ca
ca
ca
P
=
=
=
D
Sink-to-Ambient
4.74 °C/W
(
----------------------- -
(
----------------------- -
T
85 40
T
C
9.5
P
C
–
–
D
T
A
)
)
θ
cs
T
S
(continued)
θ
sa
(continued)
T
A
8-1304 (F).e
For a managed interface using thermal grease or foils,
a value of θcs = 0.1 °C/W to 0.3 °C/W is typical. The
solution for heat sink resistance is:
This equation assumes that all dissipated power must
be shed by the heat sink. Depending on the user-
defined application environment, a more accurate
model, including heat transfer from the sides and bot-
tom of the module, can be used. This equation pro-
vides a conservative estimate for such instances.
EMC Considerations
For assistance with designing for EMC compliance,
please refer to the FLTR100V10 Filter Module Data
Sheet (DS99-294EPS).
Layout Considerations
Copper paths must not be routed beneath the power
module mounting inserts. For additional layout guide-
lines, refer to the FLTR100V10 Filter Module Data
Sheet (DS99-294EPS).
θ
sa
=
(
------------------------ -
T
C
P
–
D
T
A
)
–
θ
cs
Lineage Power
April 2008