For locations, phone, fax, E-Mail see back cover
9
Hi-Rel
Grade
MGDM-04 Series
Gaia Converter FC97-008.08/06 Revision N
©
4
9- Thermal Characteristics
Characteristics
Conditions
Limit or typical
Performances
Operating ambient temperature
range at full load
Ambient temperature *
Minimum
Maximum
- 40°C
+ 85°C
Operating case temperature
range at full load
Case temperature
Minimum
Maximum
- 40°C
+105°C
Storage temperature range
Non functionning
Minimum
Maximum
- 55°C
+ 125°C
Thermal resistance
Rth case to ambient in free air
natural convection
Typical
20°C /W
Note * : The upper temperature range depends on configuration, the user must assure a max. case temperature of + 105°C.
10
100
30
110
80
70
60
90
20
40
50
25%
75%
50%
100%
Power (W)
Temperature (˚C)
Full load ambient temperature without derating : 85˚C
Maximum case temperature : 105˚C
Natural convection operation area
Additionnal cooling operation area
Maximum storage temperature : 125˚C
The MGDM-04 series operating case temperature must not exceed 105°C. The maximum ambient temperature admissible
for the DC/DC converter corresponding to the maximum operating case temperature of 105°C depends on the ambient
airflow, the mounting/orientation, the cooling features and the power dissipated.
To calculate a maximum admissible ambient temperature the following method can be used. Knowing the maximum case
temparature Tcase = 105°C of the module, the power used Pout and the efficienc
y h:
• determine the power dissipated by the module Pdiss that should be evacuated :
Pdiss = Pout(1/h
h
h
h
h
- 1)
• determine the maximum ambient temperature :
Ta = 105°C - Rth x Pdiss
where Rth is the thermal resistance from the case to ambient.
The previous thermal calculation shows two areas of operation :
• a normal operation area in a free natural ambient convection (grey area in this following graph),
• an area with cooling features (air flow or heatsink) ensuring a maximum case temperature below the maximum
operating case temperature of 105°C (white area in the following graph).
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