MELF MELF Resistors Welwyn Components Resistors WRM Series WRM Series High reliability s High reliability Predictable pulse handling capability Predictable pulse handling capability s Tolerances down to 0.1% Tolerances down to 0.1% s TCR down to 5 ppm/C TCR down to 5 ppm/C s Electrical Data WRM 0102 WRM 0204 WRM 0207 Power rating at 70C watts 0.2 0.25 0.4 Resistance range ohms R22 2M21 R22 5M1 R16 10M Limiting element voltage volts 150 200 250 TCR ppm/C 15, 25, 50 5,1 0,1 5, 25, 50, 100 15, 25, 50, 100 Resistance tolerance % 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 2.2 1.1 1.1 0.35 0.01 1 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 electrWelwynonics r Componentseserves the right to make changes in pr reserves the right to make changesoduct specification without notice or liability in product 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.bitechnologies.com www.irctt.com www.welwyn-tt.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: info welwyn-tt.com Website: www.welwyn-tt.com 01. 11 09. 11MELF MELF Resistors 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% 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 100ppm R22 R91 WRM0204 50ppm 1R 5M1 10R 1M6 22R 332K 43R 332K WRM0204 25ppm 4R7 - 500K 10R 500K 22R 402K 43R 332K 15ppm 10R 221K 22R 221K 43R 221K WRM0204 WRM0204 10ppm 22R 221K 43R 221K WRM0204 05ppm 100R 100K 100R 100K WRM0207 100ppm R22 R91 50ppm R16-10M 10R 1M6 WRM0207 WRM0207 25ppm 10R - 1M 10R 500K 51R1 - 330K 100R - 100K 15ppm 51R1 - 10K 100R - 10K WRM0207 51R1 - 10K WRM0207 10ppm WRM0207 05ppm * TC 10ppm & 5ppm is specified over the temperature range -10C to +85C. Performance Data Test Results R/R Stability class Description 0.25 0.5 1.0 10 <75 0.22 <10 75 <100 k >100 k 332 k >332 k 10 M 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 200V 300V 500V * 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.bitechnologies.com www.irctt.com www.welwyn-tt.com 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 01.11 TT electronics plc 09. 11