3810 WELWYN | Alldatasheet

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Technical content

3810 Series

  • Resistance range up to 100 T ohms (1014 ohms)
  • Designed for low current (pica ampere level) measurements
  • Low voltage coefficient
  • Hermetically sealed
  • Leakage current minimised by hermetic sealing and guard ring 3810 3811 3812 Resistance range ohms 100M to 1T 100M to 1T 1T to 100T Limiting element voltage volts 500 1000 1000 TCR (20°C to 70°C) ppm/°C -500 to -3500 Resistance tolerance % 10, 20 1, 2, 5, 10 1T to 10T; 2, 5, 10 >10T; 5, 10 Values E24 preferred Ambient temperature range °C -40 to 100 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. © 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 Electrical Data Issue D · 03.06 A subsidiary of TT electronics plc Welwyn Components Construction The Cermetox® resistive film is fired onto high quality ceramic substrate; brass end caps are forced fitted to the substrate which is then adjusted to value with a helical cut in the film; the leads are mechanically locked into the end caps and the assembly sealed into the glass envelope. All close tolerance units utilise two resistors connected in series within the glass envelope. The guard band is described, with application notes, in a Product Information sheet, available on request. Terminations Material Solder-coated Dumet 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 The serial number, resistance value and tolerance code are legend marked. The resistance value marking conforms to IEC 62. Solvent Resistance The glass envelope is coated with silicone and should not be subjected to solvents or their vapours. (See Application Notes.) Dimensions (mm) & Weight (g) PCB Min. Type L max D max f min d nom mounting Bend Wt. nom Centres Radius Physical Data LD f d 203

© 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 D · 03.06 Welwyn Components 204 Application Notes Each resistor is packed with a card stating nominal resistance value at 100 V applied, selection tolerance, date and serial number. Although the glass envelope is an excellent insulant and would be adequate in a dry atmosphere, the condensation which occurs in a normal atmosphere will provide a shunt resistance which will modify the very high resistance value. To minimise this effect all units are coated with silicone, and it is essential that this coating is not damaged; any handling should be by the terminations. For the same reason solvents must not be used. The resistors should not be used in a damp atmosphere. If moisture develops on the body the resistor should be dried for 30 minutes at 70°C and allowed to cool for a further 30 minutes in a dry atmosphere. To avoid damage to the seal between terminations and glass, the leads must be fully supported inside the point of bending during any preforming. Guard Band For details of how to use the guard band, fitted to resistors of

100 G ohms and over, ask for Product Information Sheet

detailing application notes for glass sealed resistors with guard band. Non-standard versions Units without glass envelopes but with lacquer protection are available, but will have a limited electrical performance. Measured values at a voltage other than 100V may be recorded. For non-standard items contact Welwyn Components. Packaging Each resistor is individually packed in a polythene envelope together with a card carrying measurement details and serial number (See Application Notes). Maximum Typical Load at rated voltage: 1000 hours at 20°C ∆R% 2 1 Shelf life: 12 months at room temperature ∆R% 1 0.5 Resistance to solder heat ∆R% 0.2 <0.1 Capacitance 3810 pF 0.4 3811 pF 0.2 Voltage coefficient of resistance ppm/volt 100MΩ 1TΩ 100TΩ 3810 -20 -160 3211 -10 -80 -150 3812 -10 -80 -150 Performance Data Measured at voltages of 100 and 500 volts