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
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
www.vishay.com For any questions, contact: foil@vishay.com Document Number: 63053
2 Revision: 17-Jun-08
FIGURE 1 - SCHEMATIC AND DIMENSIONS in inches (millimeters)
TOLERANCES:
A = ± 0.005" (0.13 mm)
C = ± 0.010" (0.25 mm)
D = ± 0.020" (0.51 mm)
STANDARD MARKING:
Model No.
Date Code
Resistance Value
Tolerance
Notes:
Adjustment screw 0.080" (2.03 mm) diameter with
0.025" (0.64 mm) X 0.030" (0.76 mm) slot. Tolerance on
screw dimensions is ± 0.005" (0.13 mm). Model 1240
has gold plated terminal pins 0.016" (0.41 mm) ± 0.001"
(0.03 mm) diameter, 0.200" (5.08 mm) length minimum.
1240X
0.050" (1.27 mm) C
0.040" (1.02 mm) C
VISHAY
2
3
1
CW
0.250" (6.35 mm) D
1
23
0.250" (6.35 mm) D
0.100" (2.54 mm) A
0.100" (2.54 mm) A
0.050" (1.27 mm) C
0.050" (1.27 mm) C
0.175" (4.45 mm) C
0.125" (3.18 mm) C
(bottom view)
1240W
3 12
0.050" (1.27 mm) C
VISHAY
2
13
CW
0.250" (6.35 mm) D
0.250" (6.35 mm) D
0.100" (2.54 mm) A
0.100" (2.54 mm) A
0.050" (1.27 mm) C
0.050" (1.27 mm) C
0.175" (4.45 mm) C
0.125" (3.18 mm) C
0.040" (1.02 mm) C
0.010" (0.25 mm) A
(bottom view)
Resistance
Value
Tolerance
0.055" (1.40 mm) C
0.050" (1.27 mm) C
VISHAY
3
1
CW
0.175" (4.45 mm) C
1
2 3
0.250" (6.35mm) D
0.100" (2.54 mm) A
0.100" (2.54 mm) A
0.035" (0.89 mm) C
0.250" (6.35 mm) D
0.125" (3.18 mm) C
Model No.
Date Code
0.016"
(0.41 mm) A
1240P
FIGURE 2 - POWER DERATING CURVE
- 75 - 50 - 25 0 + 25 + 50 + 75 + 100 + 125 + 150 + 175
Ambient Temperature °C
+ 85 °C
+ 100
+ 75
+ 50
+ 25
0
Percent of Rated Power
FIGURE 3 - 1240W 10 k
Ω
LOAD LIFE, 20 UNITS,
10 000 h at 0.25 W, + 85 °C (wiper at CW)
+ 2000
+ 1500
+ 1000
+ 500
0
- 500
- 1000
- 1500
- 2000
ΔR/R (ppm)
Time (h)
0 2000 4000 8000 10 0006000
Document Number: 63053 For any questions, contact: foil@vishay.com
www.vishay.com
Revision: 17-Jun-08 3
1240
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
Vishay Foil Resistors
Notes:
1. Maximum is 1.0 % A.Q.L. standard for all specifications except
TCR. (For TCR information, see notes 2 and 3.)
2. Maximum TCR applies to the 3 σ (sigma) limit or 99.73 % of a
production lot. (Measured end-to-end with wiper off the element.)
3. Measurements of TCR through the wiper are influenced more by
setting stability and the percentage of the total resistance in use
(at the wiper) than by fundamental resistance change due to
temperature alone. The parameter shown in Table 2 is a 2 s
distribution typifying the behavior of the device when used with
40 % or more of the total resistance in use.
4. Derated linearly for full power at + 85 °C to zero (0) W at + 150 °C.
See Figure 2 on previous page.
5. Independent of resistance value. 3 W maximum available on
special request.
6. All ΔR’s are measured to the tolerance specified + 0.01 Ω.
7. Whichever is greater.
Special Available Options:
Special marking
Burn-in and screening operations.
VISHAY TRIMMERS ARE INSPECTED
100 % for:
• Short-time overload
(6.25 x rated power for 5 s on; and for 30 s off - 3 cycles)
•Immersion
• Resistance tolerance check
• End resistance
• Visual-mechanical
• Dynamic tests for continuity, CRV
By sample for:
•TCR
•DWV
TABLE 5 - COMPARISON
MIL-PRF-39035/3 CHARACTERISTIC H
6)
MODEL 1240 MAXIMUM
TEST GROUP I
Conditioning
Contact resistance variation - CRV (noise)
Immersion
± 1.0 %
± 3.0 % or 3 Ω
7)
No continuous stream of bubbles
± 0.5 %
3 Ω typical, 10 Ω maximum
No continuous stream of bubbles
TEST GROUP I a
Visual and mechanical
Actual effective electrical travel
End resistance
Dielectric withstanding voltage - DWV
(atmospheric and barometric pressure)
Insulation resistance
Shaft torque
Thermal shock
Setting stability
No failures
10 to 25 turns
2 % or 2 Ω
7)
Per MIL-STD-202, methods 301 and 105
≥ 1000 MΩ
3 oz. in. maximum
± 1.0 %
± 1.0 %
No failures
21 ± 2 turns
2 Ω for values ≤ 1 kΩ;
5 Ω for values ≥ 2 kΩ;
Per MIL-STD-202, methods 301 and 105
> 1000 MΩ
3 oz. in. maximum
± 0.5 %
± 0.5 %
TEST GROUP II
Solderability Per MIL-STD-202, method 208 Per MIL-STD-202, method 208
TEST GROUP III
Resistance temperature characteristic - TCR
Moisture resistance
Contact resistance variation - CRV (noise)
± 0.005 % (± 50 ppm/°C)
± 1.0 %
3.0 % or 3 Ω
7)
± 0.001 % (± 10 ppm/°C)
± 0.5 %
3 Ω typical, 10 Ω maximum
TEST GROUP IV
Settability
Shock
Setting stability
Vibration
Setting stability
Contact resistance variation - CRV (noise)
Salt spray
± 1.0 %
± 1.0 %
± 1.0 %
± 1.0 %
± 1.0 %
3.0 % or 3 Ω
7)
No corrosion
± 0.1 %
± 0.5 %
± 0.5 %
± 0.5 %
± 0.5 %
3 Ω typical, 10 Ω maximum
No corrosion
TEST GROUP V
Solder heat
Low-temperature operation
Setting stability
Low-temperature storage
High-temperature exposure
Setting stability
Contact resistance variation - CRV (noise)
Integrity of shaft
± 1.0 %
± 1.0 %
± 2.0 %
± 1.0 %
± 3.0 %
± 2.0 %
3 % or 3 Ω
7)
No loosening or breakage
± 0.1 %
± 0.5 %
± 0.5 %
± 0.5 %
± 0.5 %
± 0.5 %
3 Ω typical, 10 Ω maximum
No loosening or breakage
TEST GROUP VI
Rotational life (200 cycles)
Contact resistance variation - CRV (noise)
Terminal strength
± 2.0 %
3 % or 3 Ω
7)
2 lbs.
± 2.0 %
3 Ω typical, 10 Ω maximum
2 lbs.
TEST GROUP VII
Life (2000 h) at + 85 °C
Life (10 000 h) at + 85 °C
± 3.0 %
± 5.0 %
± 0.1 % typical, ± 1.0 % maximum
± 0.1 % typical, ± 1.0 % maximum
TEST GROUP VIII
Solvent resistance No failures No failures
