MGDM-75 Datasheet, PDF (9/17 Pages) List of Unclassifed Manufacturers – Hi-Rel DC/DC CONVERTER 75W POWER

MGDM-75 Series
Hi-Rel
Grade
10- Thermal Characteristics
Characteristics
Conditions
Limit or typical
Operating ambient temperature range
at full load
Ambient temperature *
Minimum
Maximum
Baseplate temperature
Base plate temperature
Minimum
Maximum
Storage temperature range
Non functionning
Minimum
Maximum
Thermal resistance
Baseplate to ambient
Rth(b-a) free air
Typical
Note * : The upper temperature range depends on configuration, the user must assure a max. baseplate temperature of + 105°C.
Performances
- 40°C
see section 10-9
- 40°C
+ 105°C
- 55°C
+ 125°C
11°C/W
The MGDM-75 series maximum baseplate temperature at
To calculate a maximum admissible ambient temperature
full load must not exceed 105°C. Heat can be removed
the following method can be used.
from the baseplate via three basic
Knowing the maximum baseplate temparature Tbase =
mechanisms :
105°C of the module, the power used Pout and the
efficiency η :
• Radiation transfert : radiation is counting for less
• determine the power dissipated by the module Pdiss
than 5% of total heat transfert in majority of case, for
that should be evacuated :
this reason the presence of radient cooling is used as
Pdiss = Pout(1/η - 1) (A)
a safety margin and is not considered.
• determine the maximum ambient temperature :
Ta = 105°C - Rth(b-a) x Pdiss (B)
• Conduction transfert : in most of the applications,
heat will be conducted from the baseplate into an
where Rth(b-a) is the thermal resistance from the
attached heatsink or heat conducting member; heat is
baseplate to ambient.
conducted thruthe interface.
• Convection transfert : convecting heat t r a n s f e r
This thermal Rth(b-a) resistance is the summ of :
• the thermal resistance of baseplate to heatsink
4
into air refers to still air or forced air cooling.
(Rth(b-h)). The interface between baseplate and
heatsink can be nothing or a conducting member, a
In majority of the applications, heat will be removed from
thermal compound, a thermal pad.... The value of
the baseplate either with :
Rth(b-h) can range from 0.4°C/W for no interface down
to 0.1°C/W for a thermal conductive member inter-
• heatsink,
face.
• forced air cooling,
• the thermal resistance of heatsink to ambient air
• both heatsink and forced air cooling.
(Rth(h-a)), which is depending of air flow and given
by heatsink supplier.
The table hereafter gives some example of thermal resistance for different heat transfert configurations.
Heat transfert
Thermal resistance heatsink to air Rth(h-a)
Thermal resistance baseplate to
heatsink
Global
resistance
Free air cooling
only
No Heatsink baseplate only :
Heatsink Thermaflo 424500B0000 :
Heatsink Thermaflo 424800B0000 :
11°C/W
7,64°C/W
3,5°C/W
No need of thermal pad
Berquist Silpad* :
0,21°C/W
Berquist Silpad* :
0,21°C/W
11°C/W
7,85°C/W
3,71°C/W
Forced air cooling
200 LFM
No Heatsink baseplate only :
Heatsink Radian HS1568EX :
Heatsink Thermaflo 424800B0000 :
6,9°C/W
3,5°C/W
2,8°C/W
No need of thermal pad
Berquist Silpad* :
0,21°C/W
Berquist Silpad* :
0,21°C/W
6,9°C/W
3,71°C/W
3,01°C/W
Forced air cooling
400 LFM
No Heatsink baseplate only :
Heatsink Radian HS1568EX :
Heatsink Thermaflo 424800B0000 :
4,8°C/W
2°C/W
1,80°C/W
No need of thermal pad
Berquist Silpad* : 0,21°C/W
Berquist Silpad* : 0,21°C/W
4,8°C/W
2,21°C/W
2,01°C/W
Forced air cooling
1000 LFM
No Heatsink baseplate only :
Heatsink Thermaflo 424800B0000 :
2,8°C/W
1°C/W
No need of thermal pad
Berquist Silpad* :
0,21°C/W
2,8°C/W
1,21°C/W
Radian and Thermaflo are heasink manufacturers. «Silpad» © is a registered trademark of Berquist.
Note* : Silpad performance are for Silpad 400 with pressure conditions of 50 Psi. Surface of MGDS-150 series is 3,3 inch2.
9
© ^{Gaia Converter FC03-032.03/06 Revision G}
For locations, phone, fax, E-Mail see back cover