Document Number: 63053 For any questions, contact: foil@vishay.com
www.vishay.com
Revision: 17-Jun-08 1
1240
Vishay Foil Resistors
Bulk Metal
®
Foil Technology Precision Trimming
Potentiometers, 1/4 Inch Square, RJ26 Style, Designed to
Meet or Exceed the Requirements of MIL-PRF-39035, Char. H
FEATURES
• Temperature coefficient of resistance (TCR):
± 10 ppm/°C. (- 55 °C to + 150 °C ref. at + 25 °C);
through the wiper
3)
; ± 25 ppm/°C (see table 2 for
low values)
• Load life stability: 0.1 % typical ΔR, 1.0 % maximum
ΔR under full rated power at + 85 °C for 10 000 h
• Settability: 0.05 % typical; 0.1 % maximum
• Setting stability: 0.1 % typical; 0.5 % maximum, ΔSS
• Power rating: 0.25 W at + 85 °C
• Resistance range: 5 Ω to 10 kΩ
Note:
* See Figure 1, next page
RoHS
COMPLIANT
TABLE 1 - MODEL SELECTION
*
MODEL TERMINATION STYLE
AVERAGE
WEIGHT (g)
POWER RATING
at + 85 °C AMBIENT
NO. OF TURNS
1240
W-edge mount, top adjust
0.4 0.25 W 21 ± 2X-edge mount, side adjust
P-horizontal mount, side adjust
TABLE 2 - 1240 (RJ26) SERIES
ELECTRICAL SPECIFICATIONS
Temperature Coefficient of
Resistance (TCR) 50 Ω to 10K
End-to-end
2)
± 10 ppm/°C maximum
(- 55 °C to + 150 °C,
+ 25 °C ref.)
Temperature Coefficient of
Resistance 5, 10 and 20 Ω
Through the wiper
3)
± 20 ppm/°C
± 25 ppm/°C
Stability
Load life at 10 000 h
0.1 % typical ΔR
1.0 % maximum ΔR
(under full rated power of
0.25 W at + 85 °C)
Power Rating
4)
0.25 W at + 85 °C
Settability 0.05 % typical;
0.1 % maximum
Setting Stability 0.1 % typical;
0.5 % maximum
Contact Resistance
Variation - CRV (noise)
5)
3 Ω typical;
10 Ω maximum
Hop-off 0.25 % typical;
1.0 % maximum
High-Frequency Operation
Rise time
Inductance
Capacitance
1.0 ns without ringing
0.08 µH typical
0.5 pF typical
Operating Temperature Range - 55 °C to + 150 °C
TABLE 3 - VALUES VS. TOLERANCES
STANDARD RESISTANCE VALUES
(in Ω)
STANDARD
TOLERANCE
5, 10 ± 10 %
20, 50, 100, 200, 500, 1K, 2K, 5K, 10K ± 5 %
TABLE 4 - MECHANICAL SPECIFICATIONS
Adjustment Turns
21 ±
2
Mechanical Stops
Wiper idles - no discontinuity
Internal
Terminations
All welded - no flux
Case Material
1240X - diallyl-phthalate: green (DAP)
1240W - diallyl-phthalate: green (DAP)
1240P - thermoplastic: black
Shaft Torque
3 oz. in. maximum
Backlash
0.005 % typical
