Ultra Low Profile Power Resistors

WDBR Series

Terminations

The following termination options are available

Option

Code

Nominal Dimensions

Solder pad only

SnAg (96S)

I

Flying leads

UL3134 40A, 600V

L

Push-on connectors

(WDBR1,2,3,5&7)

T

Performance Data

Maximum

Mounted on a 0.53°C/W heatsink with 5m/s forced air cooling, air temperature 25°C.

ΔR%

5

Derating at heatsink temperatures >160°C

See Fig. 2

Application Notes

A heatsink with thermal resistance

≤0.53°C/W will enable the component to operate at its continuous power rating.

Thermal grease (e.g. Dow Corning DC340) should be used and the heatsink should have a surface finish of <6.3

μm

with flatness of <0.05mm. The resistor should be mounted using a screw head bolt of size M5 for WDBR2, 3, 5 & 7,

M3 for WDBR1 and M2 for WDBR1/2. This should be torqued to 2.5Nm ±10%.

WDBR resistors will fail safe (open circuit) under overload fault conditions and still maintain a 1kV dielectric withstand.

General Note

Welwyn Components reserves the right to make changes in product specification without notice or liability.

All information is subject to Welwyn’s own test data and is considered accurate at time of print.

©Welwyn Components Limited

Welwyn Electronics Park, Bedlington, Northumberland, NE22 7AA, England. Tel: 01670 822181 Fax: 01670 829465 Web: www.welwyn-tt.com

11mm

8.5mm

8mm

6mm

0.8mm

9mm

9mm

250mm

3mm

0

20

40

60

80

100

120

0

50

100

150

200

250

Heatsink Temperature (°C)

Fig. 2: Temperature Derating

1ms

1ms

8s

P pk

2s

Fig. 1: Duty Cycle Waveform