Vishay Intertechnology Inc.'s QPL series of Bulk Metal Foil ultra-high-precision Accutrim trimming potentiometers are designed to meet and substantially exceed the requirements of MIL-PRF-22097 Char. F. For avionics, military, and space applications (AMS), the QPL-approved RJ26-style devices offer low end-to-end TCR of ±10ppm/°C from -55°C to 150°C, and ±25ppm/°C through the wiper, load life stability of 0.1 percent typical under full rated power at +85°C for 1,000 hours, and a <0.05 percent typical settability.
The new 1242 series of ultra-high-precision trimmers features a Bulk Metal Foil resistive element that has a unique inherent temperature and load life stability. Their advanced, virtually backlash-free 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 Vishay Foil trimmers have a multi-fingered wiper traversing a flat element. The wiper engagement pressure can be much higher when the load is spread out over various wiper tangs, so the sensitivity to shock and vibration in Foil-based trimmers is virtually eliminated for most applications. Cermet trimmers have a much greater mass of the rider block and begin to show response to the lower frequencies of vibration and shock.
For high-reliability AMS applications, the 1242 devices are required when the value of resistance or voltage division in a circuit must be adjusted to compensate for environmental influences, when the desired circuit performance cannot be procured and retained through manufacturing, or it is unknown what precision is required.
The devices offer a multi-fingered, noble metal wiper engaging a planar surface of etched Foil for low TCR end-to-end (five times tighter than required by MIL-PRF-39035 Char. H) and through the wiper.
The 1242 trimmers feature a resistance range from 20Ω to 5kΩ, resistance tolerance of ±10 percent, and 0.25W power rating. The devices are essentially non-inductive with rise times as fast as 1ns for high-frequency applications. For increased reliability, the trimmers provide the utmost in ESD immunity, withstanding electrostatic discharges up to 25kV.
Vishay Accutrim 1242 Trimming Potentiometers
Vishay Intertechnology
