JBW030-Series Power Module: dc-dc Converters
36-75 Vdc Input; 3.3 Vdc and 5 Vdc Outputs; 30 W
Data Sheet
March 27, 2008
Thermal Considerations (continued)
9
8
Forced Convection Cooling
7
6
5
4
3
2
1
0
To determine the necessary airflow, determine the
power dissipated by the unit for the particular applica-
tion. Figures 19 and 20 show typical power
2.0 ms-1(400 ft./min.)
1.0 ms-1(200 ft./min.)
0.5 ms-1(100 ft./min.)
NATURAL
dissipation for these power modules over a range of
output currents. With the known power dissipation and
a given local ambient temperature, the appropriate air-
flow can be chosen from the derating curves in
Figure 21. For example, if the JBW030A dissipates 6.2
W, the minimum airflow in a 80 °C environment is
CONVECTION
30
40
50
60
70
80
90
100
–1
1 ms (200 ft./min.).
LOCAL AMBIENT TEMPERATURE, TA (˚C)
8-1051(C)
7
VI = 36 V
VI = 48 V
VI = 75 V
6
5
4
3
2
1
0
Figure 21. Forced Convection Power Derating with
No Heat Sink; Either Orientation
Heat Sink Selection
Several heat sinks are available for these modules.
The case includes through-threaded mounting holes
allowing attachment of heat sinks or cold plates from
either side of the module. The mounting torque must
not exceed 0.56 N-m (5 in./lb.).
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
5.5
6
6.5
OUTPUT CURRENT, IO (A)
1-0762
Figure 22 shows the case-to-ambient thermal resis-
tance, θ (°C/W), for these modules. These curves can
be used to predict which heat sink will be needed for a
particular environment. For example, if the JBW030A
dissipates 7 W of heat in an 80 °C environment with an
Figure 19. JBW030F Power Dissipation vs.
Output Current
8
7
–1
airflow of 0.7 ms (130 ft./min.), the minimum heat
sink required can be determined as follows:
6
VI = 75 V
VI = 48 V
θ ≤ (TC, max – TA) ⁄ PD
5
4
3
where:
θ = module’s total thermal resistance
TC,max = case temperature (See Figure 18.)
TA = inlet ambient temperature
(See Figure 18.)
VI = 36 V
2
1
0
0
1
2
3
4
5
6
PD = power dissipation
OUTPUT CURRENT, IO (A)
1-0761
θ ≤ (100 – 80)/7
θ ≤ 2.9 °C/W
Figure 20. JBW030A Power Dissipation vs.
Output Current
From Figure 22, the 1/2 in. high heat sink or greater is
required.
12
Lineage Power
LINEAGEPOWER [ LINEAGE POWER CORPORATION ]
