Mini 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 Issue D · 09.06
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
Type TCR Tolerance
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
Description 0.25 0.5 1.0
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
Current noise < 0.05 µV/V < 0.25 µV/V < 3 µV/V
Solderability Dipped area shall be covered with a smooth
and bright solder coating of at least 96%
Voltage coefficient < 0.5 . 106/V
Voltage proof No flashover or breakdown