High Voltage Thick Film Resistors Welwyn Components VRW Series * VRW37 meets the requirements of BS / EN / IEC 60065 * High working voltage to 10kV in compact size * High ohmic range to 68M * High pulse load capability * Robust flameproof coating material * RoHS compliant Electrical Data Power rating at 70 C VRW25 VRW37 VRW68 0.25 0.5 1.0 100K to 30M 100K to 30M 100K to 68M 1600 3500 10000 watts Resistance range (Ohms) Limiting element voltage volts dc or ac peak Isolation voltage volts TCR 700 ppm/ C Resistance Tolerance 200 % 1, 2, 5 Standard Values E24 or E96 Thermal Impedance C/watt Ambient temperature range Physical Data 140 112 70 -55 to +155 C C (Dimensions (mm) & Weight (g) Type L Max D Max f min d Nom PCB mount centres Min bend radius Wt. nom VRW25 6.2 2.5 21 0.60.05 10.2 0.6 0.3 VRW37 9.0 3.7 19.6 0.80.05 12.7 1.2 0.5 VRW68 15.5 5.0 27 0.80.05 20.3 1.2 1.15 d D L f Construction Terminations Resistive thick film material is applied to high-grade ceramic rods. Tin-plated steel caps are force fitted and the termination wires are welded to the caps. The value is obtained by a helical cut in the film and finally the resistor body is protected by a cement coating. Material: Hot tin dipped 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 Marking Solvent Resistance 1% tolerance resistors are colour coded with 5 bands. 2% and 5% tolerance have 4 bands. IEC62 colours are used. The body protection and marking are resistant to all normal industrial cleaning solvents suitable for printed circuits. Flammability The resistor coating will not burn 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. (c) 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 70 A subsidiary of TT electronics plc Issue C * 05.08 07.06 High Voltage Thick Film Resistors Welwyn Components SQP Series VRW Performance Data Maximum Load at rated voltage (1000hrs at 70C) R% Typical 1.5* 0.4 Derating from rated power at 70 C zero at 155 C Overload (10 x 5s 45s off 6.25 x Pr not 2exceeding 5s on, at 6.25 x Pratnot exceeding x LEV) 2 x LEV) R% 12 0.15 Damp heat steady state (56 days, 40C, R% 1.5 0.1 R% 1.5 90% RH) Climatic sequence 0.2 Climatic category 55/155/56 Temperature rapid change R% 0.5 0.05 Resistance to solder heat R% 0.5 0.05 Vibration R% 0.5 Voltage Proof 0.05 volts 700 min * 2% for ohmic values above 24M Pulse Performance Performace Pulse Vmax (kV) 100 VRW25 VRW37 10 VRW68 1 0.1 1 10 100 Value (megohms) Maximum peak voltage in accordance with "IEC 60065 chapter 14.1" 50 discharges from a 1nF capacitor charged to V max. 12 discharges/minute. Application Notes 1. Due to operating temperature limits imposed by some PCB materials, derating may be necessary. An estimate of the temperature rise to be expected at the center of the body can be calculated using the thermal impedance figures given under Electrical Data. 2. VRW resistors can be supplied with radial, goalpost or lancet pre-formed leads. The VRW37 is also available in an SMD format with Z formed leads and packed in blister tape. Consult Factory for details. Packaging Our standard packaging for VRW is taped and boxed. The critical dimensions are shown in Figure 1. The component wires will not protrude beyond the outside edge of the tapes. Alternative packaging is available by request. Pre-formed resistors are supplied loose packed in plastic bags or boxes. Type b VRW25/37 VRW68 c 52 2mm 5 0.5mm 73 2mm 10 0.5mm c f1 6 mm f2 6 mm b Body location f1-f2 (c) 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 1.4mm 05.08 71 High Voltage Thick Film Resistors Welwyn Components SQP VRW Series Series Ordering Procedure Example: VRW25 at 1.2 megohms and 5% tolerance in an ammo pack box of 5000 pieces - VRW25-1M2JI Type Value (use IEC62 code) Tolerance (use IEC62 code) F G J 1% 2% 5% Packing I Ammo VRW25 VRW37 VRW68 5000/box 2500/box 1000/box Standard (c) 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 C * 05.08 07.06 71