Custom resistor networks
16 November 2010
Hermetically-sealed metal or HTCC packaging enables harsh environment operation to 175°C.
Providing military and aerospace electronics design engineers with the capability to integrate ultra-precision resistor networks into high reliability circuits for harsh environments, especially for elevated temperatures, TT electronics’ BI Technologies offers a series of custom thin film resistor networks in hermetically-sealed metal or HTCC (high-temperature co-fired ceramic) packages.
Designated the Model 144 Series, these high-reliability resistor networks can be specified with custom schematics, non-standard resistance values and ultra-tight resistance and TCR tolerances to meet the requirements for military electronics systems, avionics and aerospace circuits.
According to Mike Torres, Fixed Film Product Manager for BI Technologies Electronic Components Division, the Model 144 Series thin film custom resistor networks provide tighter resistance tolerances and TCR tracking performance than other precision networks. “We can produce custom networks with up to 25 resistors that mix and match resistor values based on the customer’s requirements,” he explained. “And, through our proprietary processing and packaging, we can achieve ratio tolerances between individual resistors in the network down to <±0.01%, and TCR tracking tolerances to <±1ppm/°C.”
The networks’ construction and packaging is designed specifically for high reliability applications where plastic packaged devices cannot be specified due to elevated temperatures or other harsh environmental conditions. Available in hermetically sealed through-hole DIP and surface mount flatpack packages with 3 to 28 pins, the Model 144 Series networks also feature a proprietary passivation coating over the precision nichrome resistive elements to protect against humid environments, and the package cavity is filled with inert nitrogen.
The custom high-reliability resistor networks are suitable for a range of applications, including instrumentation amplifiers, precision voltage dividers, measurement bridge circuitry, ladder networks and other precision analogue circuits in aerospace and military electronic systems.
The Model 144 Series custom resistor networks feature resistance values from 10Ω to 3MΩ, in tolerances down to ±0.025% (ratio tolerances to ±0.01%), in ratio values up to 1:1000. Typical TCRs are ±25ppm°/C, with tracking between resistors available to ±1ppm/°C. Operating temperature range is from -55°C to +175°C.
Screening and testing to MIL-STD-883, MIL-STD-1835, MIL-PRF-38534, MIL-STD-38510 and MIL-STD-202 is available on request. Model 144 Series networks can also be ordered in RoHS-compliant versions. Typical lead times are from 10 to 16 weeks, with no minimum order quantity required.
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