Ultra-High Value
Precision Resistors
3810 Series
Welwyn Components
•
Resistance range up to 100 T ohms
(10
14
ohms)
•
Designed for low current (pica ampere level)
measurements
•
•
•
Low voltage coefficient
Hermetically sealed
Leakage current minimised by hermetic
sealing and guard ring
Electrical Data
3810
Resistance range
Limiting element voltage
TCR (20°C to 70°C)
Resistance tolerance
Values
Ambient temperature range
°C
ohms
volts
ppm/°C
%
10, 20
100M to 1T
500
3811
100M to 1T
1000
-500 to -3500
1, 2, 5, 10
E24 preferred
-40 to 100
1T to 10T; 2, 5, 10 >10T; 5, 10
3812
1T to 100T
1000
Physical Data
Dimensions (mm) & Weight (g)
Type
3810
3811
3812
L max
25.0
42.9
48.0
D max
6
6
6
f min
30
30
30
d nom
0.6
0.6
0.6
PCB
mounting
Centres
29.2
47.1
52.2
Min.
Bend
Radius
0.6
0.6
0.6
1.5
2.2
2.5
Wt. nom
d
D
L
f
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.
®
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.)
Terminations
Material
Strength
Solder-coated Dumet wire.
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
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
Issue D · 03.06
© 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
203
Ultra-High Value
Precision Resistors
3810 Series
Welwyn Components
Performance Data
Maximum
Load at rated voltage: 1000 hours at 20°C
Shelf life: 12 months at room temperature
Resistance to solder heat
Capacitance
3810
3811
∆R%
∆R%
∆R%
pF
pF
2
1
0.2
0.4
0.2
Typical
1
0.5
<0.1
Voltage coefficient of resistance
100MΩ
3810
3211
3812
-20
-10
-10
1TΩ
-160
-80
-80
ppm/volt
100TΩ
-150
-150
Measured at voltages
of 100 and 500 volts
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).
© 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
204
Issue D · 03.06
Microcontroller MCU
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