Mini Melf Resistors Welwyn Components WRM Series • High reliability • Predictable pulse handling capability • Tolerances down to 0.1% • TCR down to 5 ppm/°C Electrical Data WRM 0102 WRM 0204 Power rating at 70°C watts 0.2 0.25 0.4 Resistance range ohms R22 – 2M21 R22 – 10M R22 – 8M2 Limiting element voltage volts TCR ppm/°C Resistance tolerance WRM 0207 150 200 250 15, 25, 50 5, 15, 25, 50 25, 50 % 0.1, 0.25, 0.5, 1.0, 2, 5 Standard values E24 & E96 Thermal impedance k/W Ambient temperature range 250 200 °C Insulation resistance 140 -55 to +125 >1010 ohms Physical Data Dimensions (mm) and weight (g) D max D1 max 2.2 1.1 1.1 0.35 0.01 3.6 1.4 1.4 0.5 0.02 6.0 2.2 2.2 1.1 0.08 Type L max WRM 0102 WRM 0204 WRM 0207 K min Weight L D D1 L1 K 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 4 or 5 bands depending on type. 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. 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. A subsidiary of TT electronics plc © Welwyn Components Limited · Bedlington, Northumberland NE22 7AA, UK Telephone: +44 (0) 1670 822181 · Facsimile: +44 (0) 1670 829465 · Email: [email protected] · Website: www.welwyn-tt.com Issue D · 09.06 Mini Melf Resistors Welwyn Components WRM Series TCR and Tolerance Range 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 – – – – – – * TC 10ppm & 5ppm is specified over the temperature range -10°C to +85°C. Performance Data Results ∆ R/R ± Test Stability class Description 0.25 0.5 1.0 10 Ω – <75 Ω 0.22 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 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 < 0.05 µV/V < 0.25 µV/V < 3 µV/V Endurance* Load life Current noise Solderability Dipped area shall be covered with a smooth and bright solder coating of at least 96% < 0.5 . 106/V Voltage coefficient Voltage proof 200V 300V 500V * Resistors to be mounted on a PC-board according to IEC 115-1, clause 4.27.1 © Welwyn Components Limited Bedlington, Northumberland NE22 7AA, UK Telephone: +44 (0) 1670 822181 · Facsimile: +44 (0) 1670 829465 · Email: [email protected] · Website: www.welwyn-tt.com Issue D · 09.06 Mini Melf Resistors Welwyn Components WRM Series Single Pulse Maximum Pulse Load WRM 0102 WRM 0204 WRM 0207 100 Pulse Load Pmax W 10 1 0,1 10 µs 100 µs 1 ms 10 ms 100 ms 1s 10 s Pulse Duration ti Continuous Pulses Continuous Pulse Load Pmax Maximum Pulse Load WRM 0102 WRM 0204 WRM 0207 100 W 10 1 0,1 10 µs 100 µs 1 ms 10 ms 100 ms 1s 10 s Pulse Duration ti 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. Ordering Procedure Example: WRM0204 at 1 kilohm, 1% tolerance and 50ppm/ºC TCR on a reel of 3000 pieces Type WRM 0204 C - 1K0 F I Size Packing TCR C 50ppm/ºC T 10ppm/ºC D 25ppm/ºC V 5ppm/ºC Y 15ppm/ºC I Tape 0102 3000 / reel (7”) 0204 3000 / reel (7”)* 0207 1500 / reel (7”) Standard * High precision parts may be supplied on 1000 piece reels – please enquire Value (use IEC62 code) Tolerance (use IEC62 code) B 0.1% D C 0.25% F 0.5% G 2% 1% J 5% © Welwyn Components Limited Bedlington, Northumberland NE22 7AA, UK Telephone: +44 (0) 1670 822181 · Facsimile: +44 (0) 1670 829465 · Email: [email protected] · Website: www.welwyn-tt.com Issue D · 09.06