Fusible Metal Film Resistors Welwyn Components FA8025 series • Predictable fusing characteristics • Flameproof protection Electrical Data FA8225 FA8325 Power rating at 70˚ C watts 0.25 0.5 1.5 Resistance range ohms 0R1 - 10k 0R1 - 27k 0R15 - 22k Limiting element voltage TCR FA8425 volts 250 350 500 ppm/˚ C 250 250 250 Resistance tolerance % 5 Standard values E24 preferred Thermal impedance ˚ C/watt Ambient temperature range 150 90 120 ˚C -55 to 155 Physical Data Dimensions (mm) & Weight (g) L max D max f min d nom PCB mounting centres FA8225 6.2 2.5 2.3 21 0.6 10.2 0.6 0.3 FA8325 9.0 3.4 19.6 0.8 12.7 1.2 0.6 FA8425 14.5 5.1 23.8 0.8 20.3 1.2 1.1 Type Min. bend radius Wt. nom d dia D L f Construction Marking The metal film is deposited on a high purity ceramic rod. End caps are force fitted and termination wires welded to the caps. The resistive film is adjusted to the required value by a helical cut; finally the cement protection is applied to the resistor body and marked with indelible ink. Resistors are colour coded with five bands. Four of the bands are used to indicate value and tolerance, with IEC 62 colours being used. On FA8325 and FA8425 types a fifth yellow band denotes constant voltage fusibility. Solvent Resistance Terminations Material Solder-coated copper wire. Strength The terminations meet the requirements of IEC 68.2.21. Solderability The terminations meet the requirements of IEC 115-1, Clause 4.17.3.2. The body protection and marking are resistant to all normal industrial cleaning solvents suitable for printed circuits. Flammability The resistors will not burn or emit incandescent particles under any condition of applied temperature or power overload. 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 B · 01.07 03.02 Issue C 153 Fusible Metal Film Resistors Welwyn Components FA8025 series Performance Data Maximum Typical Load: 1000 hours at 70˚C R% 2 0.5 Shelf life: 12 months at room temperature R% 0.5 0.2 Temperature rapid change R% 0.5 0.2 Resistance to solder heat R% 0.5 0.2 Derating from rated power at 70˚ C zero at 155˚ C Predicting Fusing Time For Defined Power Input Fusible Resistors: Typical Fusing Window Graphs 1 to 3. Graph 4. Normal rated power Fusing: After fusing the final resistance value will be 50 times the initial value. See graph for explanation of fusing curves. Graph 1 Min power for guaranteed fusing Fusing Time (secs) Max fusing time Max sale fusing power Min fusing time Initial Power (watts) Packaging The preferred method of packaging is taped and ammo packed, see figure 1 for critical dimensions. Alternative packaging is available by special request. Graph 2 Lead Formed resistors can also be supplied. Standard options of Lancet, Radial and Goalpost forming are shown in Lead Form Information section. Figure 1 c f1 Graph 3 6 f2 b 6 Body Location f1 – f2 Type 1.4 mm FA82* FA82/FA83 FA84 b 26 52 67 c 5 5 10 Standard Quantities Per Package Type Ammopack FA8225 FA8325 FA8425 5000 2500 1000 © 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 154 01.07 Issue C B · 03.02