Moulded Surface Mount

Wirewound Resistors

WSM Series

Telephone: +44 (0) 1670 822181 · Facsimile: +44 (0) 1670 829465 · Email: info@welwyn-tt.com · Website: www.welwyn-tt.com

46

Issue C · 04.02

Welwyn Components

Physical Data

Dimensions (mm)

Ao

Bo

Ko

W

P

t

Po

WSM1

4.2

7.62

4.2

16

8

0.36

4 ± 0.1

WSM2

6.75

11.95

5.22

24

12

0.36

4 ± 0.1

WSM3

7.3

18.3

6.7

32

12

0.4

4 ± 0.1

All other dimensions as per EIA481 standard

WSM1

WSM2

WSM3

Load at rated power: 1000 hrs @ 70°C

∆R%

2 ± 0.001

Ω

2 ± 0.001

Ω

3 ± 0.001

Ω

Dry heat

1000 hrs @ 155°C

∆R%

2 ± 0.001

Ω

2 ± 0.001

Ω

3 ± 0.001

Ω

Short term overload

∆R%

2 ± 0.001

Ω

Derating from rated power @ 70°C

zero at 155°C

Moisture

∆R%

1 ± 0.001

Ω

1 ± 0.001

Ω

1.5 ± 0.001

Ω

Temperature cycling

∆R%

1 ± 0.001

Ω

Resistance to solder heat

∆R%

1 ± 0.001

Ω

Isolation voltage

V

1,000

Insulation resistance

ohms

>1000M

Substrate bend

∆R%

0.2 ± 0.001

Ω

Performance Data

Note: The power ratings to be applied depend upon the board used and the ambient temperature.

WSM_C.qxd

29/4/03

10:38 am

Page 2