FA8325

Fusible Metal Film Resistors FA8025 series Welwyn Components • Predictable fusing characteristics • Flameproof protection Electrical Data FA8225 Power rating at 70˚ C Resistance range Limiting element voltage TCR Resistance tolerance Standard values Thermal impedance Ambient temperature range ˚ C/watt ˚C 150 watts ohms volts ppm/˚ C % 0.25 0R1 - 10k 250 250 FA8325 0.5 0R1 - 27k 350 250 5 E24 preferred 120 -55 to 155 90 FA8425 1.5 0R15 - 22k 500 250 Physical Data Dimensions (mm) & Weight (g) PCB mounting centres 10.2 12.7 20.3 Min. bend radius 0.6 1.2 1.2 Wt. nom 0.3 0.6 1.1 d dia D L f Type FA8225 FA8325 FA8425 L max 6.2 9.0 14.5 D max 2.5 2.3 3.4 5.1 f min 21 19.6 23.8 d nom 0.6 0.8 0.8 Construction 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. Marking 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 Strength Solder-coated copper wire. The terminations meet the requirements of IEC 68.2.21. 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. Solderability The terminations meet the requirements of IEC 115-1, Clause 4.17.3.2. 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 B 03.02 Issue C · 01.07 © 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 153 Fusible Metal Film Resistors FA8025 series Welwyn Components Performance Data Maximum Load: 1000 hours at 70˚C Shelf life: 12 months at room temperature Derating from rated power at 70˚ C Temperature rapid change Resistance to solder heat R% R% 0.5 0.5 R% R% 2 0.5 zero at 155˚ C 0.2 0.2 Typical 0.5 0.2 Predicting Fusing Time For Defined Power Input Graphs 1 to 3. Fusible Resistors: Typical Fusing Window 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 Fusing Time (secs) Min power for guaranteed fusing Max fusing time Min fusing time Initial Power (watts) Max sale fusing power 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 b Body Location f1 – f2 f2 6 1.4 mm Type b c FA82* 26 5 FA82/FA83 52 5 FA84 67 10 Standard Quantities Per Package Type Ammopack FA8225 5000 FA8325 2500 FA8425 1000 © 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 154 Issue C · 03.02 B 01.07