dc025 Lineage Power, dc025 Datasheet - Page 15

• Manufacturer Part Number: dc025
• Description: Dc025 Dual-output-series Power Modules
• Manufacturer: Lineage Power

March 2008
Thermal Considerations
Air Velocity
Figure 20. Total Power Dissipation vs. Local
Figure 21. Case-to-Ambient Thermal Resistance
Lineage Power
10.0
9.0
8.0
7.0
6.0
5.0
4.0
3.0
2.0
1.0
0.0
7.0
6.0
5.0
4.0
3.0
2.0
1.0
0.0
CONV
NAT
40
2.03 ms
1.02 ms
0.51 ms
0.31 ms
Ambient Temperature and Air Velocity
vs. Air Velocity
0.25
(50)
LOCAL AMBIENT TEMPERATURE, T
50
(continued)
–1
–1
–1
CONVECTION
–1
(100 ft./min.)
(400 ft./min.)
(200 ft./min.)
(100)
0.51
(60 ft./min.)
VELOCITY, ms
NATURAL
60
(150)
0.76
(200)
1.02
70
–1
(ft./min.)
(continued)
(250)
1.27
80
(300)
1.52
A
(°C)
90
(350)
1.78
8-988(C)
8-989(C)
100
(400)
2.03
Use of Heat Sinks and Cold Plates
The DC025 Dual-Output-Series Power Modules case
includes through-threaded M3 x 0.5 mounting holes
allowing attachment of heat sinks or cold plates from
either side of the module. The mounting torque must
not exceed 0.56 N/m (5 in.-lb.).
The following thermal model can be used to determine
the required thermal resistance of the sink to provide
the necessary cooling:
where P
represents the interfacial contact resistance between
the module and the sink, and θ
thermal impedance (°C/W). For thermal greases or
foils, a value of θ
The required θ
tion:
Note that this equation assumes that all dissipated
power must be shed by the heat sink. Depending on
the user-defined application environment, a more accu-
rate model including heat transfer from the sides and
bottom of the module can be used. This equation pro-
vides a conservative estimate in such instances.
For further information, refer to the Thermal Energy
Management CC-, CW-, DC-, and DW-Series 25 W
to 30 W Board-Mounted Power Modules Technical
Note.
P
D
D
Tc
is the power dissipated by the module, θ
SA
CS
is calculated from the following equa-
θ
18 Vdc to 36 Vdc Input; 25 W
θ
SA
= 0.1 °C/W—0.3 °C/W is typical.
CS
=
------------------- - θ
P
T
C
D
total
–
T
Ts
SA
A
–
is the sink-to-ambient
CS
θ
SA
CS
T
15
A