Vishay has unveiled a series of Bulk Metal Foil high-precision Accutrim trimming potentiometers. The devices possess 1¼inch rectilinear RJ12 style and are designed to meet the requirements of the MIL-PRF-22097 Char. F. The devices offer low end-to-end TCR of ±10ppm/°C from -55 to +150°C, +25°C reference and ±25ppm/°C through the wiper.
The 1202 series of high-precision trimmers features a Bulk Metal Foil resistive element that possesses a unique temperature and load life stability. The trimmers' advanced, virtually backlash-free adjustment mechanism allows them to set quickly and accurately. The setting can be maintained through temperature cycling and vibration, as well as thermal and mechanical shock. The devices offer a multifingered metal wiper that traverses a planar surface of etched Foil for low TCR end-to-end and through the wiper.
The trimmers feature 0.1% typical setting stability, a wide resistance range from 2 to 20kOhm and resistance tolerance from ±5%. The devices offer 0.5W power rating at +85°C and 25±2-turn adjustments. The trimmers can withstand electrostatic discharges up to 25kV and they possess good ESD immunity for better reliability.
The series offers high resolution. When it is synthesised by a combination of uniform resistance material, multiple wiper contact points and multiple resistance circuit paths, it yields a settability of less than 0.05%. This settability eliminates the loss of expensive technician time while trying to set trimmers or balance circuits. There are no turns of wire to be traversed, causing a step function, and no contact resistance variation to cause an irregular change in resistance with mechanical adjustment.
The trimmers feature an "O"-ring to prevent ingress of fluids during any board cleaning operation. The devices offer gold-plated terminations with tin/lead terminations. Special available options include 45-turn adjusting screws, special length for lead wires (L, LB style), hooked leads, alternate bushing and PC pin combinations, burn-in and screening operations and special markings. The stability and linearity of the Foil trimmer eliminates the use of a buffering resistor in series with the trimmer or a linearising resistor in parallel with the trimmer.
