VHB75W-Q48-S15 CUI Inc, VHB75W-Q48-S15 Datasheet - Page 4

• Manufacturer Part Number: VHB75W-Q48-S15
• Description: CONVERTER DC/DC 75W 15V 5A
• Manufacturer: CUI Inc
• Series: V-Infinity VHB75Wr
• Type: With Remote On/Off and UVLOr

Specifications of VHB75W-Q48-S15

• Voltage - Input (min): 18V
• Voltage - Input (max): 75V
• Number Of Outputs: 1
• Power (watts) - Manufacture Series: 75W
• Power (watts) - Max: 75W
• 1st Output: 15 VDC @ 5A
• 2nd Output: -
• 3rd Output: -
• Voltage - Isolation: 1.5kV (1500V)
• Mounting Type: Through Hole
• Package / Case: 9-DIP Module, 1/2 Brick
• Size / Dimension: 2.40" L x 2.28" W x 0.50" H (61mm x 57.9mm x 12.7mm)
• Operating Temperature: -40°C ~ 100°C
• Efficiency: 85%
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 102-2255; VHB75W-Q48-S15

PART NUMBER: VHB75W
APPLICATION NOTES
1. OUTPUT DE-RATING
The operating case temperature range for VHB75W is -40 ~ +100°C. When operating the VHB75W series, proper derating or cooling
is needed. The maximum case temperature under any operating condition should not exceed 100°C.
Example:
Solution:
Determine Power dissipation (Pd):
Determine airflow:
Check above Power de-rating curve:
Verifying:
Where:
What is the minimum airflow necessary for a VHB75W-Q48-S12
operating at nominal line, an output current of 6.25 A, and a
maximum ambient temperature of 40°C?
Given: Vin=48 V dc, Vo=12 V dc, Io=6.25 A
Pd=Pi-Po=Po(1-η)/η
Pd=12×6.25×(1-0.84)/0.84=14.29 W
Given: Pd=14.29 W and Ta=40°C
minimum airflow= 400 ft./min.
The maximum temp. rise ΔT = Pd × Rca=14.29×3.64=52.02°C. The maximum case temperature Tc=Ta+ΔT=92.02°C<100°C
The Rca is thermal resistance from case to ambience.The Ta is ambient temperature and the Tc is case temperature.
20050 SW 112
Power Dissipated vs Ambient Temperature and Air Flo w
th
Ave. Tualatin, Oregon 97062
FIGURE 1. OUTPUT DERATING (FORCED CONVECTION WITH NO HEAT SINK)
Ambient Temperature ,Ta(Deg. C)
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DESCRIPTION: half-brick dc-dc converter
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Chart of Thermal Resistance vs Air Flow
AIR FLOW RATE
Natural Convection
20ft./min. (0.1m/s)
100 ft./min. (0.5m/s)
200 ft./min. (1.0m/s)
300 ft./min. (1.5m/s)
400 ft./min. (2.0m/s)
500 ft./min. (2.5m/s)
600 ft./min. (3.0m/s)
700 ft./min. (3.5m/s)
800 ft./min. (4.0m/s)
Natural Convection
20 ft./min. (0.1 m/s)
100 ft./min. (0.5 m/s)
200 ft./min. (1.0 m/s)
300 ft./min. (1.5 m/s)
400 ft./min. (2.0 m/s)
500 ft./min. (2.5 m/s)
600 ft./min. (3.0 m/s)
700 ft./min. (3.5 m/s)
800 ft./min. (4.0 m/s)
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page
date
TYPICAL Rca
7.12
6.21
5.17
4.29
3.64
2.96
2.53
2.37
2.19
04/2011
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