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Powersolve Electronics Ltd, Units 8, 9 and 12 The Paddock, Hambridge Road, Newbury, Berks RG14 5TQ

Tel: 01635 521858 Fax: 01635 523771 Email: sales@powersolve.co.uk

3

Derating:

The operating case temperature range of the PS50 series is -40°C to +100°C. When operating the PS50 series,

proper derating or cooling is needed.

The following curve is the derating curve of a PS50 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)

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

15

10

5

0

Ambient Temperature, Ta(Deg. C)

0

10

20

30

40

50

60

70

80

90

100

20

25

30

35

40

45

50

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)

Forced Convection Power Derating without Heat Sink

High Density DC-DC Modules