Construction

The resistor element is an etched bulk metal foil, bonded to

an alumina substrate. Connections to the foil are made by

copper wires welded to the foil to minimise thermal e.m.f.

Before encapsulation, the resistor element is coated with

silicone rubber to isolate the element from mechanical stress

which would adversely affect the carefully balanced

construction and result in poor resistance/temperature

characteristics.

Ultra Precision Bulk Metal

Film Resistors

4800 series

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

187

Dimensions (mm) & Weight (g)

Type

L max

H max

W max

T min

d nom

S nom

Wt. nom

4802

8.9

10.2

3.8

30

0.6

5.1

1

4812

7.5

8

2.5

30

0.6

5.1

0.6

4804

15.2

13.2

3.8

30

0.6

10.2

1.5

4805

22.6

13.2

3.8

30

0.6

17.8

2

4832

9.7

5.4

9.7

30

0.6

1.5

1.1

Physical Data

L

4802/12/04/05

4832

W

S

H

T

d dia

L

H

T

d

W

S

Issue B · 03.02

Welwyn Components

Actual

Maximum

Typical

Load at commercial rating: 1000 hours at 70°C

∆R%

0.05

0.02

Dry heat: 1000 hours at 155°C

∆R%

0.05

0.02

Shelf life: 12 months at room temperature

∆R%

0.0025

Derating from rated power at 70°C

Zero at 155°C

Short term overload

∆R%

0.01

0.005

Climatic category

55/155/56

Climatic

∆R%

0.05

0.03

Long term damp heat

∆R%

0.05

0.03

Temperature rapid change

∆R%

0.01

0.005

Resistance to solder heat

∆R%

0.01

0.005

Vibration and bump

∆R%

0.01

0.005

Noise. (in a decade of frequency)

µV/V

Below level of

Voltage coefficient of resistance

ppm/V

practicable measurement

Insulation Resistance

ohms

>1000M

Inductance

µH

0.2

0.08

Capacitance

pF

1

0.5

Terminations

Material

Solder coated copper wire

Strength

The terminations meet the requirements of

IEC 68.2.21.

Solderability

The terminations meet the requirements of

IEC 115-1, Clause 4.17.3.2.

Marking

Type reference, resistance value, tolerance and date code are

legend marked. The resistance value conforms to IEC 62.

Solvent Resistance

The protection will withstand all normal industrial solvents

suitable for cleaning printed circuit boards.

Packaging

All components are supplied loose packed in either plastic bags

or panel boxes. Quantity per box will depend on resistor size.

Performance Data