25
6�4 Thermal Management
This section provides supplemental information regarding thermal management of the LPS36.
NOTE: 2
When the LPS36 is operating normally at maximum rated load, the shelf level rate of
heat dissipation exceeds the allowable limit of 27.9 W/sq.ft. per Section 4.1.6 of GR-63-
CORE (Issue 6).
Alpha recommends leaving a minimum of 27.3 (22.9) inches vacant vertical rack space
for each 23" (19") shelf installation to meet the required shelf-level rate of heat dissipa-
tion. In addition, special equipment room cooling may be required.
NOTE: 1
Blanking plates must be installed in all the empty converter slots when forced air or fan
cooling is used for the application.
6�4�1 Natural Convection (Ta = -40°C to +45°C)
The high efficiency of LPS36, given its high power density, makes it possible to operate up to 45
°
C ambient at full
power without the need for fan tray or external airflow. When installing the LPS36 shelf on a system that only relies
on natural convection for cooling, proper spacing from surrounding equipment should be observed in order to
facilitate effective ventilation.
For operation above 45°C, the output power should be derated at 2.5W/°C as per the graph below.
45
°
C
65
°
C
0
10
20
30
40
50
60
70
80
90
100
110
-50
-40
-30
-20
-10
0
10
20
30
40
50
60
70
80
LP
S3
6
Av
er
ag
e
O
ut
pu
t p
er
C
han
ne
l (
W
)
Ambient Temperature (
°
C)
Output Power Derating Curve
LPS36 Average Output = Line loss (I
2
R) + Remote down-conv Remote equipment
load.
NOTE:
Figure 12 — Ambient Temperature
