
Powersolve Electronics Ltd. Units 8A, Arnhem Road, Newbury, RG14 5RU. England
www.powersolve.co.uk
3
Derating:
The operating case temperature range of the PS100 series is -40°C to +100°C. When operating the PS100 series,
proper derating or cooling is needed.
The following curve is the derating curve of a PS100 without heat sink.
Where:
The power dissipation (Pd):
Pd = Pi - Po = Po (1-n) /n
The ther
mal r
esistances are listed below:
Chart of Thermal Resistance vs Air Flow:
The temperature rise ( T ):
T = Pd * Rca
Application Note
AIR FLOW RA
TE
TYPICAL Rca
Natural Convection 20ft./min. (0.1m/s) 7.12 °C/W
100 ft./min. (0.5m/s) 6.21 °C/W
200 ft./min. (1.0m/s) 5.17 °C/W
300 ft./min. (1.5m/s) 4.29 °C/W
400 ft./min. (2.0m/s) 3.64 °C/W
500 ft./min. (2.5m/s)
2.96
°
C/W
600 ft./min. (3.0m/s) 2.53 °C/W
700 ft./min. (3.5m/s) 2.37 °C/W
800 ft./min. (4.0m/s)
2.19
°C/W
Power Dissipated vs Ambient Temperature and Air Flow
1
5
10
5
0
Ambient Temperature, Ta(Deg. C)
Power Disspated, Pd (Watts)
0
10 20
30
40 50
60
70 80 90
100
20
25
3
0
35
40
4
5
5
0
N
atural Convection
2
0 ft./min. (0.1 m/s)
1
00 ft./min. (0.5 m/s)
200 ft./min. (1.0 m/s)
300 ft./min. ( 1.5 m/s)
4
00 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)
Forced Convection Power Derating without Heat Sink
High Density DC-DC Modules
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