Bulk Metal
®
Foil Technology Ultra High Precision Trimming Potentiometers,
1
/
4
" Square, RJ26 Style, Designed to Meet or Exceed The Requirements of
MIL-PRF-39035, Char. H with a Smooth and Unidirectional Output
Accutrim™ 1240 (RJ26 Style)
Vishay Foil Resistors
Document Number: 63053 For any questions, contact: foil@vishaypg.com www.vishayfoilresistors.com
Revision: 16-Oct-13 1
INTRODUCTION
Vishay Foil Resistors’ (VFR) precision trimmers have the
Bulk Metal® Foil resistive element which possesses a unique
inherent temperature and load life stability. Plus, their
advanced virtually back lash-free adjustment mechanism
makes them easy to set quickly and accurately and keeps
the setting exactly on target.
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)
A smooth and unidirectional resistance with
leadscrew adjustment
Load life stability: 0.1 % typical R, 1.0 % maximum R
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, DSS
Power rating: 0.25 W at + 85 °C
Resistance range: 5 to 10 k
Tolerance: ± 5 %, ± 10 %
Electrostatic discharge (ESD) at least to 25 kV
Terminal finish: gold plated (tin/lead finish is available on
request)
CERMET
Wiper Travel
Resistance
Wiper Travel
Resistance
BULK METAL
FOIL WIREWOUND
Wiper Travel
Resistance
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
Note
• See Figure 1, next page
TABLE 2 - 1240 (RJ26) SERIES
ELECTRICAL SPECIFICATIONS
Temperature Coefficient of
Resistance (TCR) 50 to 10 k
± 10 ppm/°C maximum
(- 55 °C to + 150 °C,
+ 25 °C ref.)
End-to-end (2)
Temperature Coefficient of
Resistance 5, 10 and 20
± 20 ppm/°C
Through the wiper (3) ± 25 ppm/°C
Stability
Load life at 10 000 h
End-to-end (2)
0.1 % typical R
1.0 % maximum R
(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 typical;
10 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 )
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