By Vishay Foil Resistors (Division of Vishay Precision Group) 60
Vishay Foil Resistors offers Bulk Metal® foil ultra-high-precision Accutrim™ trimming potentiometers. The 3/4″ rectilinear devices offer extremely low end-to-end TCR of ±5 ppm/°C (1285G) and ±15 ppm/°C (1280G) from -55°C to 125°C (25°C reference) and ±25 ppm/°C through the wiper. They also offer load life stability of 0.1% typical under full rated power at 25°C for 2,000 hours and a < 0.05% typical settability.
Vishay Foil's 1280G and 1285G trimmers feature a Bulk Metal foil resistive element that possesses a unique inherent temperature and load life stability. Their advanced, virtually backlash-free (< 0.05%) adjustment mechanism makes them easy to set quickly and accurately, and maintains that setting through temperature cycling and vibration, as well as thermal and mechanical shock.
The devices offer a multi-fingered, noble metal wiper engaging a planar surface of etched foil for low TCR end-to-end and through the wiper. Other technologies, such as wirewound and cermet trimmers, cannot be relied upon to demonstrate an acceptable TCR through the wiper.
In addition to their low TCR and excellent load life stability, the 1280G and 1285G trimmers feature a 0.1% typical setting stability, a wide resistance range from 10 Ω to 20 kΩ, and resistance tolerances of ±5% (1285G) and ±10% (1280G). The devices offer a 0.75 W power rating at 25°C and 26 ±2 turn adjustments. For increased reliability, the trimmers provide the utmost in ESD immunity, withstanding electrostatic discharges up to 25 kV.
The devices provide unidirectional, infinite resolution, which when synthesized by a combination of an absolutely uniform resistance material, multiple wiper contact points, and multiple resistance circuit paths, yields a uniquely accurate settability of less than 0.05%. 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.