P R E C I S I O N
B U L K
M E T A L
®
F O I L
T E C H N O L O G Y
VISHAY 1280 AND 1285G SERIES
Precision Trimming Potentiometers
3/4" Rectilinear,
±5
ppm/°C and
±15
ppm/°C TCR
FEATURES
• Temperature Coefficient of Resistance (TCR):
<15 ppm/°C (Model 1280G); <5 ppm/°C (Model 1285G)
4
(–55°C to +125°C Ref. @ +25°C); through the wiper
±50
ppm/°C
• Load Life Stability: 0.5% Maximum
∆R
under Full Rated
Power @ +25°C for 2,000 hours
• Settability: 0.05% Typical; 0.1% Maximum
• Setting Stability: 0.1% Typical; 0.5% Maximum,
∆SS
• Power Rating: 0.75 watts @ +25°C
• Resistance Range: 10
Ω
to 20K
Ω
• Resistance Tolerance:
±10%, ±5
%
• Backlash: < 0.05%
• Tap Test: 0.05% Typical; 0.1% Maximum
TABLE 1 - 1280G AND 1285G SERIES
ELECTRICAL SPECIFICATIONS
Resistance Tolerance
Resistance Range
T.C.R. Model 1280G
T.C.R. Model 1285G
4
Power
Settability
Setting Stability
Roll-on, Roll-off
Load-Life Stability
End Resistance
C.R.V.
3
Frequency Characteristics
NOTES
1. 5% Available on Special Order.
2. Typical is a designer’s reference which represents that 85% of the
units supplied over a long period of time, will be at least the figure
shown or better.
3. The 1280G can be screened for low noise, if required.
4. For model 1285G 10
Ω
and 20
Ω
TCR is
±10
ppm/°C
5. Panel mount available on special order.
Model 1280G 10%
1
Model 1285G 5%
10
Ω
to 20K
Ω
+15 ppm/°C (–55°C to +25°C)
–15 ppm/°C (+25°C to +125°C)
+5 ppm/°C (–55°C to +25°C)
–5 ppm/°C (+25°C to +125°C)
0.75 W @ +25°C derated linearly
to zero watts @ +125°C (See Fig, 2)
0.05% Typical
2
; 0.1% Maximum
0.1% Typical; 0.5% Maximum,
∆SS
0.25% Typical; 1.0% Maximum
0.5%
∆R
after 2,000 hours under
Full Rated Power @ +25°C
2
Ω
Maximum
3
Ω
Typical; 10
Ω
Maximum
10 ns rise time @ 1K
Ω
to 100 MHz
TABLE 2 - 1280G AND 1285G SERIES
MECHANICAL SPECIFICATIONS
Adjustment Turns
Backlash
Stops
Sealed
Torque
Weight
Construction
Case Material
Lead Screw
Wiper
Rider Block
Element
Lead Material
26
±2
turns
<0.05%
clutch, wiper idles
+85°C water immersion
5 oz. in. Max.
1.5 grams Max.
Valox
®
Brass
Precious Metal Brush
Nylon
Bulk Metal
®
Foil
Gold Plated Phosphor Bronze
TABLE 3 - STANDARD VALUES
10
Ω,
20
Ω,
50
Ω,
100
Ω,
200
Ω,
500
Ω
1K, 2K, 5K, 10K, 20K
TRIMMERS
HOW TO ORDER 1280/1285 SERIES PARTS:
Please specify Vishay Model 1202 Precision Trimming Potentiometers
as follows:
Example:
1280G
Model No.
100R
Resistance Value
10%
Tolerance
144
VISHAY FOIL RESISTORS,
63 Lincoln Highway, P.O. Box 4004, Malvern, PA 19355-0988 • Phone (610) 644-1300
App. Eng. Phone (610) 251-5289 • App. Eng, Fax (610) 640-4487 • Sales Phone (610) 251-5842 • Sales Fax (610) 640-9081
P R E C I S I O N
B U L K
M E T A L
®
F O I L
T E C H N O L O G Y
VISHAY 1280 AND 1285G SERIES
Schematic and Dimensions
FIGURE 1 - 1280G / 1285G SCHEMATIC AND DIMENSIONS
5
0.750" (19.05mm) C
0.060"
(1.52mm) A
0.190"
(4.83mm) B
0.010"
(0.25mm) A
0.050"
(1.27mm) A
0.039" (0.99mm) A
0.020" (0.51mm) A
0.110"
(2.79mm) A 0.270"
(6.86mm) B
0.190"
(4.83mm) B
1
2
3
0.200"
(5.08mm) B
0.030"
(0.76mm) A
0.010"
(0.25mm) A
0.100"
(2.54mm) B
0.200"
(5.08mm) A
0.500" (12.70mm) A
0.125"
(3.18 mm) B
1
CW
0.030"
(0.76mm) A
2
3
TOLERANCES
A =
±0.005"
(0.13mm)
B =
±0.010"
(0.25mm)
C =
±0.015"
(0.38mm)
FIGURE 2 - POWER DERATING CURVE
PERCENT OF
RATED POWER
+100
+75
+25°C
TRIMMERS
+50
+25
–75 –50 –25 0 +25 +50 +75 +100 +125 +150
AMBIENT TEMPERATURE
°C
VISHAY FOIL RESISTORS,
63 Lincoln Highway, P.O. Box 4004, Malvern, PA 19355-0988 • Phone (610) 644-1300
App. Eng. Phone (610) 251-5289 • App. Eng, Fax (610) 640-4487 • Sales Phone (610) 251-5842 • Sales Fax (610) 640-9081
145
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