Resistors
MELF
Make Possible
Welwyn Components
MELF RResistoresisstors
WRM Series
WRM Series
High reliability
High reliability
Predictable pulse handling capability
Predictable pulse handling capability
Tolerances down to 0.1%
Tolerances down to 0.1%
TCR down to 5 ppm/C
TCR down to 5 ppm/C
All parts are Pb-free and comply with EU Directive 2011/65/EU (RoHS2)
Electrical Data
WRM 0102 WRM 0204 WRM 0207
Power rating at 70C watts 0.125 0.25 0.4
Resistance range ohms
4R7 - 110K R22 5M1 R22 10M
Limiting element voltage volts 150 200 250
TCR ppm/C 50 5,1 0,1 5, 25, 50, 100 15, 25, 50, 100
Resistance tolerance %
1 0.1, 0.25, 0.5, 1.0, 2, 5
Standard values E24 & E96
Thermal impedance k/W 250 200 140
Ambient temperature range C -55 to +125
10
Insulation resistance ohms >10
Physical Data
Dimensions (mm) and weight (g)
L
1
Type L D D K Weight
max max max min
D D
WRM 0102 0.01 1
2.2 1.35 1.3 0.3
WRM 0204 3.7 1.55 1.55 0.5 0.02
1
L K
WRM 0207 6.1 2.4 2.4 0.5 0.08
Construction
Terminations
A metal film is deposited onto a high dissipation ceramic
Material Plated steel cap.
former to which tin plated teminating caps are fitted.
Solderability The pure tin finish produces ageing free
The resistor is adjusted to value by a helical cut in the film
contacts on which low melting solders can
and the body is protected by a lacquer coating.
be used. Dipped area shall be covered with
a smooth and bright solder coating after
Marking
3 seconds immersion at 215C.
Resistance values are colour coded with four bands,
three indicating value and one indicating the multiplier.
Solvent Resistance
(Note this describes standard marking, but certain values
The body protection and marking are resistant to all normal
may still be supplied with the addition of a tolerance band
industrial cleaning solvents suitable for printed circuit boards.
following the multiplier.)
General Note
General Note
TT Electronics reservWelwyn Componentses the right to mak reserves the righte changes in product specific to make changes in pration without notice or liability.oduct specification without notice or liability.
All information is subject to Welwyns own data and is considered accurate at time of going to print. A subsidiary of
All information is subject to TT Electronics own data and is considered accurate at time of going to print.
www.ttelectronicsresistors.com
TT electronics plc
Welwyn Components Limited Bedlington, Northumberland NE22 7AA, UK
TT Electronics plc
Telephone: +44 (0) 1670 822181 Facsimile: +44 (0) 1670 829465 Email: [email protected] Website: www.welwyn-tt.com 01. 11
07.14MELF
MELF
Resistors Make Possible
Resistors
WRM Series
Welwyn Components
WRM Series
TCR and Tolerance Range
Type TCR Tolerance
Reference
5% 2% 1.0% 0.5% 0.25% 0.1%
50ppm
WRM0102 4R7 - 110K
100ppm R22 R91
50ppm 1R 5M1 10R 1M6 22R 332K 43R 332K
25ppm 4R7 - 500K 10R 500K 22R 402K 43R 332K
WRM0204
15ppm 10R 221K 22R 221K 43R 221K
10ppm 22R 221K 43R 221K
05ppm 100R 100K 100R 100K
R22 R91
100ppm
1R-10M
WRM0207
25ppm 10R - 1M 10R 680K 51R1 - 330K 100R - 100K
15ppm 51R1 - 10K 100R - 10K
51R1 - 10K
* TC 10ppm & 5ppm is specified over the temperature range -10C to +85C.
Performance Data
Test
Results R/R
0204 & 0207: 10R - <75R 0102: 4R7 - 110K, 0204 &
0204 & 0207: 75R - 100K
& >100K - 332K 0207: R22 - <10R & >332K - 10M
Short time overload* 0.05% + 0.01 0.1% + 0.01 0.25% + 0.05
Bending test* 0.05% + 0.01 0.1% + 0.01 0.25% + 0.05
Resistance to soldering heat 0.05% + 0.01 0.1% + 0.01 0.25% + 0.05
Temperature rapid change 0.05% + 0.01 0.1% + 0.01 0.25% + 0.05
Endurance*
Load life 1000h 0.25% + 0.05 0.25% + 0.05 0.5% + 0.05
8000 h 0.5% + 0.05 0.5% + 0.05 1.0% + 0.05
Climatic sequence* 0.25% + 0.05 0.5% + 0.05 1.0% + 0.05
Damp heat steady state* 0.25% + 0.05 0.5% + 0.05 1.0% + 0.05
Current noise < 0.05 V/V < 0.25 V/V < 3 V/V
Solderability Dipped area shall be covered with a smooth
and bright solder coating of at least 96%
6
Voltage coefficient < 0.5 . 10 /V
Voltage proof
No flashover or breakdown
* Resistors to be mounted on a PC-board according to IEC 115-1, clause 4.27.1
General Note
TT Electronics reserves the right to make changes in product specification without notice or liability.
All information is subject to TT Electronics own data and is considered accurate at time of going to print.
www.ttelectronicsresistors.com
Welwyn Components Limited Bedlington, Northumberland NE22 7AA, UK
TT Electronics plc
Telephone: +44 (0) 1670 822181 Facsimile: +44 (0) 1670 829465 Email: [email protected] Website: www.welwyn-tt.com 01.11
07.14