10
Tyco Electronics Corp.
Data Sheet
May 1998
18 Vdc to 36 Vdc Input, 5 Vdc Output; 50 W to 150 W
FC050A, FC100A, FC150A Power Modules: dc-dc Converters;
Feature Descriptions (continued)
Output Overvoltage Clamp
The output overvoltage clamp consists of control cir-
cuitry, independent of the primary regulation loop, that
monitors the voltage on the output terminals. The con-
trol loop of the clamp has a higher voltage set point
than the primary loop (see Feature Specications
table). This provides a redundant voltage-control that
reduces the risk of output overvoltage.
Thermal Considerations
Introduction
The power modules operate in a variety of thermal
environments; however, sufcient cooling should be
provided to help ensure reliable operation of the unit.
Heat-dissipating components inside the unit are ther-
mally coupled to the case. Heat is removed by conduc-
tion, convection, and radiation to the surrounding
environment. Proper cooling can be veried by mea-
suring the case temperature. Peak temperature occurs
8-582(C).c
Note: Top view, measurements shown in millimeters and (inches).
Pin locations are for reference only.
Figure 18. Case Temperature Measurement
Location
The temperature at this location should not exceed
95 °C. The maximum case temperature can be limited to
a lower value for extremely high reliability. The output
power of the module should not exceed the rated power
for the module as listed in the Ordering Information table.
For additional information about these modules, refer to
the
hermal Management for High-Power Board-
Mounted Power Modules
Technical Note (TN97-009EPS).
Heat Transfer Without Heat Sinks
Derating curves for forced-air cooling without a heat
sink are shown in
Figure 19. These curves can be used
to determine the appropriate airow for a given set of
operating conditions. For example, if the unit dissipates
20 W of heat, the correct airow in a 40 °C environment
is 1.0 m/s (200 ft./min.).
8-587(C)
Figure 19. Power Derating vs. Local Ambient
Temperature and Air Velocity
Heat Transfer with Heat Sinks
The power modules have threaded #4-40 fasteners,
which enable heat sinks or cold plates to be attached to
the module. The mounting torque must not exceed
0.56 N-m (5 in.-lb.).
Thermal derating with heat sinks is expressed by using
the overall thermal resistance of the module. Total mod-
ule thermal resistance (
θca) is dened as the maximum
case temperature rise (
TC, max) divided by the module
power dissipation (PD):
The location to measure case temperature (TC) is
shown in
Figure 18. Case-to-ambient thermal resis-
tance vs. airow for various heat sink congurations is
obtained by experimental testing of heat sinks, which
are offered in the product catalog.
PARALLEL
+
SENSE
–
+
OUT
–
TRIM
CASE
ON/OFF
+
–
IN
MEASURE CASE
TEMPERATURE HERE
18 (0.7)
76 (3.0)
FC150A9
DC-DC Power Module
IN:DC 28V, 6.7A OUT:DC 5V, 30A
150W
MADE IN USA
Lucent
Protected by U.S. Patents: 5,036,452 5,179,365
TUV Rheinland
¨
30
POWER
DISSIPATION,
P
D
(W)
LOCAL AMBIENT TEMPERATURE, TA (
°C)
20
10
020
40
60
80
40
100
0
0.1 m/s (20 ft./min.)
NATURAL CONVECTION
0.5 m/s (100 ft./min.)
1.0 m/s (200 ft./min.)
1.5 m/s (300 ft./min.)
2.0 m/s (400 ft./min.)
2.5 m/s (500 ft./min.)
3.0 m/s (600 ft./min.)
3.5 m/s (700 ft./min.)
4.0 m/s (800 ft./min.)
θca
TC max
,
PD
---------------------
TC
TA
–
()
PD
------------------------
==