QHW075G71 Lineage Power, QHW075G71 Datasheet - Page 15

• Manufacturer Part Number: QHW075G71
• Description: CONVERTER DC/DC 2.5V 38W OUT
• Manufacturer: Lineage Power
• Series: QHWr
• Type: Isolated with Remote On/Offr

Specifications of QHW075G71

• Output: 2.5V
• Number Of Outputs: 1
• Power (watts): 38W
• Mounting Type: Through Hole
• Voltage - Input: 36 ~ 75V
• Package / Case: 8-DIP Module
• 1st Output: 2.5 VDC @ 15A
• Size / Dimension: 2.28" L x 1.45" W x 0.50" H (57.9mm x 36.8mm x 12.7mm)
• Power (watts) - Rated: 38W
• Operating Temperature: -40°C ~ 100°C
• Efficiency: 86%
• Approvals: CE, CSA, UL, VDE
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• 3rd Output: -
• 2nd Output: -
• 4th Output: -

April 2008
Thermal Considerations
Heat Transfer with Heat Sinks
Figure 31. Heat Sink Power Derating Curves;
Figure 32. Heat Sink Power Derating Curves;
Lineage Power
20
15
10
20
15
10
5
0
5
0
0
0
Natural Convection; Longitudinal
Orientation
1.0 m/s (200 lfm); Transverse Orientation
10
10
1/2 IN. HEAT SINK
1/4 IN. HEAT SINK
LOCAL AMBIEMT TEMPERATURE, T
LOCAL AMBIENT TEMPERATURE, T
1 IN. HEAT SINK
NO HEAT SINK
20
20
30
30
40
40
dc-dc Converters: 36 to 75 Vdc Input, 2.5 Vdc Output; 25 W to 50 W
50
50
60
60
1 IN. HEAT SINK
1/2 IN. HEAT SINK
1/4 IN. HEAT SINK
NO HEAT SINK
(continued)
70
70
(continued)
80
80
A
A
(°C)
(°C)
90 100
90 100
8-2890 (F)
8-2891 (F)
Figure 33. Heat Sink Power Derating Curves;
These measured resistances are from heat transfer
from the sides and bottom of the module as well as the
top side with the attached heat sink; therefore, the
case-to-ambient thermal resistances shown are gener-
ally lower than the resistance of the heat sink by itself.
The module used to collect the data in Figure 28 had a
thermal-conductive dry pad between the case and the
heat sink to minimize contact resistance. The use of
Figure 28 is shown in the following example.
Example
If an 85 °C case temperature is desired, what is the
minimum airflow necessary? Assume the QHW100G1
module is operating at V
of 20 A, maximum ambient air temperature of 40 °C,
and the heat sink is 1/4 inch. The module is oriented in
the transverse direction.
Solution
Given: V
Determine P
20
15
10
5
0
I
T
T
Heat sink = 1/4 inch
P
0
O
A
C
I
D
= 48 V
= 20 A
= 40 °C
1.0 m/s (200 lfm); Longitudinal
Orientation
= 85 °C
= 9.5 W
1/2 IN. HEAT SINK
1/4 IN. HEAT SINK
10
D
LOCAL AMBIENT TEMPERATURE, T
1 IN. HEAT SINK
by using Figure 27:
NO HEAT SINK
20
30
I
= 48 V and an output current
40
50
60
70
80
A
(°C)
90 100
8-2892 (F)
15