AA10C_07 Datasheet, PDF (10/12 Pages) Astec America, Inc – 36 Vdc to 75 Vdc Inputs, 10 W

Technical Reference Notes (TRN)
AA10C Series
36 Vdc to 75 Vdc Inputs, 10 W
Thermal Considerations
The power converter operates in a variety of thermal environments: however, sufficient cooling
should be provided to help ensure reliable operation of the converter. Heat-dissipating
components are thermally coupled to the PCB. Heat is removed by conduction, convection, and
radiation to the surrounding environment. Proper cooling can be verified by measuring the PCB
temperature. See figure 23 for PCB temperature measurement location.
Heat Transfer Characteristics
Increasing airflow over the converter enhances the heat transfer via convection. Figure 16 shows
the maximum power that can be dissipated by the converter without exceeding the maximum
case temperature versus local ambient temperature (T_A) for natural convection through 3.0 m/s
(600 ft/min).
Systems in which these converters are used generate airflow rates of 0.25 m/s (50 ft/min) due to
other heat dissipating components in the system. Therefore, the natural convection condition
represents airflow rates of approximately 0.25 m/s (50 ft/min). Use of Figure 16 is shown in the
following example.
Example
What is the minimum airflow required for an 050S operating at 48 V, an output current of 2.0 A,
and maximum ambient temperature of 95 ºC.
Solution:
Given: Vi = 48 V, Io = 3.0 A, T_A = 95 ºC.
Determine P_D (Figure 20): P_D = 2.2 W.
Determine airflow (Figure 16): v = 1.0 m/s (200 ft/min)
AA10C SERIES
Power Derating Curve
Nat. Conv.
1.0 m/s (200 ft/min)
2.0 m/s (400 ft/min)
3.0 m/s (600 ft/min)
3
2.5
2
1.5
1
0.5
0
25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120
Ambient Temperature (ºC)
Figure 16. Forced Convection Power Derating
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ASTEC POWER - Andover
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