Dimensions (mm) and weight (g)
Type L D D1K Weight
max max max min
WRM 0102 2.2 1.1 1.1 0.35 0.01
WRM 0204 3.6 1.4 1.4 0.5 0.02
WRM 0207 6.0 2.2 2.2 1.1 0.08
MELF
Resistors
WRM Series
•High reliability
•Predictable pulse handling capability
•Tolerances down to 0.1%
•TCR down to 5 ppm/°C
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 data and is considered accurate at time of going to print.
© Welwyn Components Limited · Bedlington, Northumberland NE22 7AA, UK
Telephone: +44 (0) 1670 822181 · Facsimile: +44 (0) 1670 829465 · Email: info@welwyn-tt.com · Website: www.welwyn-tt.com
WRM 0102 WRM 0204 WRM 0207
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Standard values E24 & E96
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Electrical Data
Physical Data
07. 08
A subsidiary of
TT electronics plc
Welwyn Components
L
K
L1
D
D1
Construction
A metal film is deposited onto a high dissipation ceramic
former to which tin plated teminating caps are fitted.
The resistor is adjusted to value by a helical cut in the film
and the body is protected by a lacquer coating.
Marking
Resistance values are colour coded with four bands,
three indicating value and one indicating the multiplier.
(Note this describes standard marking, but certain values
may still be supplied with the addition of a tolerance band
following the multiplier.)
Terminations
Material Plated steel cap.
Solderability The pure tin finish produces ageing free
contacts on which low melting solders can
be used. Dipped area shall be covered with
a smooth and bright solder coating after
3 seconds immersion at 215°C.
Solvent Resistance
The body protection and marking are resistant to all normal
industrial cleaning solvents suitable for printed circuit boards.
MELF
Resistors
WRM Series
© Welwyn Components Limited Bedlington, Northumberland NE22 7AA, UK
Telephone: +44 (0) 1670 822181 · Facsimile: +44 (0) 1670 829465 · Email: info@welwyn-tt.com · Website: www.welwyn-tt.com 07. 08
Welwyn Components
TCR and Tolerance Range
* TC 10ppm & 5ppm is specified over the temperature range -10°C to +85°C.
* Resistors to be mounted on a PC-board according to IEC 115-1, clause 4.27.1
Performance Data
ecnareloTRCTepyT
Reference
5% 2% 1.0% 0.5% 0.25% 0.1%
WRM0102 ±50ppm R22 – R91 IRO – 9R1 10R – 2.21M 47RS – 221K 100R – 221K –
WRM0102 ±25ppm – – 10R – 221K 47R5 – 221K 100R – 221K 100R – 100K
WRM0102 ±15ppm – – – 100R – 100K 100R – 100K 100R – 100K
WRM0102 ±10ppm – –––––
WRM0102 ±05ppm – –––––
WRM0204 ±50ppm R22 – R91 – 1R – 10M 10R – 475K 22R – 332K 43R – 332K
WRM0204 ±25ppm – – 10R – 475K 10R – 475K 22R – 332K 43R – 332K
WRM0204 ±15ppm – – – 10R – 221K 22R – 221K 43R – 221K
WRM0204 ±10ppm – ––– 22R – 221K 43R – 221K
WRM0204 ±05ppm – ––– 100R – 100K 100R – 100K
WRM0207 ±50ppm R22 – R91 – 1R – 8.2M 10R – 1M – –
WRM0207 ±25ppm – – – 10R – 1M – –
WRM0207 ±15ppm – –––––
WRM0207 ±10ppm – –––––
WRM0207 ±05ppm – –––––
Test Results ∆R/R ±
Stability class
0.15.052.0noitpircseD
10 Ω– <75 Ω0.22 Ω– <10 Ω
75 Ω– <100 kΩ>100 kΩ– 332 kΩ>332 kΩ– 10 MΩ
Short time overload* ≤0.05% + 0.01 Ω ≤ 0.1% + 0.01 Ω ≤ 0.25% + 0.05 Ω
Bending test* ≤0.05% + 0.01 Ω ≤ 0.1% + 0.01 Ω ≤ 0.25% + 0.05 Ω
Resistance to soldering heat ≤0.05% + 0.01 Ω ≤ 0.1% + 0.01 Ω ≤ 0.25% + 0.05 Ω
Temperature rapid change ≤0.05% + 0.01 Ω ≤ 0.1% + 0.01 Ω ≤ 0.25% + 0.05 Ω
Endurance*
Load life 1000h ≤0.25% + 0.05 Ω ≤ 0.25% + 0.05 Ω ≤ 0.5% + 0.05 Ω
8000 h ≤0.5% + 0.05 Ω ≤ 0.5% + 0.05 Ω ≤ 1.0% + 0.05 Ω
Climatic sequence* ≤0.25% + 0.05 Ω ≤ 0.5% + 0.05 Ω ≤ 1.0% + 0.05 Ω
Damp heat steady state* ≤0.25% + 0.05 Ω ≤ 0.5% + 0.05 Ω ≤ 1.0% + 0.05 Ω
V/Vµ 3 <V/Vµ 52.0 <V/Vµ 50.0 <esion tnerruC
htooms a htiw derevoc eb llahs aera deppiDytilibaredloS
and bright solder coating of at least 96%
01 . 5.0 <tneiciffeoc egatloV 6/V
foorp egatloV
200V 300V 500V
MELF
Resistors
WRM Series
© Welwyn Components Limited Bedlington, Northumberland NE22 7AA, UK
Telephone: +44 (0) 1670 822181 · Facsimile: +44 (0) 1670 829465 · Email: info@welwyn-tt.com · Website: www.welwyn-tt.com 07. 08
Welwyn Components
100
10
1
0,1
10 µs 100 µs 1 ms 10 ms 100 ms 1 s 10 s
Pulse Duration ti
Pulse Load Pmax
WRM 0102
WRM 0204
WRM 0207
W
100
10
1
0,1
10 µs 100 µs 1 ms 10 ms 100 ms 1 s 10 s
Pulse Duration ti
Continuous Pulse Load Pmax
WRM 0102
WRM 0204
WRM 0207
W
Single Pulse
Maximum Pulse Load
Continuous Pulses
Maximum Pulse Load
Type WRM 0204 C - 1K0 F I
Size
TCR
Value (use IEC62 code)
Tolerance (use IEC62 code)
Packing
C 50ppm/ºC T 10ppm/ºC
D 25ppm/ºC V 5ppm/ºC
Y 15ppm/ºC
B 0.1% D 0.5% G 2%
C 0.25% F 1% J 5%
0102 3000 / reel (7”)
ITape 0204 3000 / reel (7”)* Standard
0207 1500 / reel (7”)
Ordering Procedure
Example: WRM0204 at 1 kilohm, 1% tolerance and 50ppm/ºC TCR on a reel of 3000 pieces -
* High precision parts may be supplied on 1000 piece reels – please enquire
Packaging
The WRM 0102 and 0204 resistors are supplied reeled on 8mm blister tape.
WRM 0207 resistors are supplied on 12mm blister tape.
Packaging complies with the requirements of IEC 286-3.
