Powersolve PSQ75 Series - Manual (Page 3)

Powersolve Electronics Ltd. Units 8A, Arnhem Road, Newbury, RG14 5RU. England
Tel:01635 521858 Fax: 01635 523771 Email: [email protected]
www.powersolve.co.uk
3
Derating:
The operating case temperature range of the PSQ75 series is -40°C to +100°C. When operating the PSQ75 series,
proper derating or cooling is needed.
The following curve is the derating curve of a PSQ75 without heat sink.
Where:
The power dissipation (Pd):
Pd = Pi - Po = Po (1-n) /n
The thermal resistance are listed below:
Chart of Thermal Resistance vs Air Flow:
The temperature rise ( T ):
T = Pd * Rca
Application Note
AIR FLOW RATE TYPICAL Rca
Natural Convection 20ft./min. (0.1m/s) 10.1 °C/W
100 ft./min. (0.5m/s) 8.0 °C/W
200 ft./min. (1.0m/s) 5.4 °C/W
300 ft./min. (1.5m/s) 4.4 °C/W
400 ft./min. (2.0m/s) 3.4 °C/W
Power Dissipated vs Ambient Temperature and Air Flow
Natural Convectio
20 ft./min. (0.1 m/s)
n
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)
12
8
10
6
4
2
0
0 10 20 30 40 50 60 70 80 90 100
Ambient Temperature, Ta(Deg. C)
Po
w
er
D
is
sp
at
ed
,P
d
(W
at
ts
)
External Output
High Density DC-DC Modules