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Low absolute TR characterizes Z-Foil resistor

Posted: 19 Sep 2008 ?? ?Print Version ?Bookmark and Share

Keywords:resistor Z-Foil? TCR PCR? ultrahigh precision VPR221Z?

Vishay Intertechnology Inc. introduces the VPR221Z ultrahigh-precision Z-Foil resistor. The new device provides an industrial-grade absolute TCR of 0.05ppm/C from 0C to +60C and 0.2ppm/C from -55C to +125C, +25C ref., a power rating up to 8W at +25C per MIL-PRF-39009 (1.5W in free air), an excellent power coefficient ("R due to self heating") of 4ppm/W typical, and a tolerance of 0.01 percent.

The new VPR221Z resistor is built on Vishay's Z- Foil technology, which provides a significant reduction of the resistive component's sensitivity to ambient temperature variations (TCR) and applied power changes (PCR), according to the company. Z-Foil improves stability by an order of magnitude compared to any other resistor technology, allowing designers to guarantee a high degree of accuracy in fixed-resistor applications, claims Vishay.

While other resistor technologies can take several seconds or even minutes to achieve a steady state thermal stabilization, the VPR221Z has an almost instantaneous thermal stabilization time, and a nearly immeasurable 1.0ns rise time without ringing. Optimized for military and space applications according to EEE-INST-002 screening and MIL-PRF-39009, the resistor is built to handle unconventional environmental conditions with minimal drift.

The VPR221Z allows designers to achieve much better performance by combining a range of ultra-high-precision specifications in a single device. These specifications include a load-life stability of 0.005 percent (50ppm) for 2000 hours at +25C; a low voltage coefficient of Offering the utmost in ESD immunity, the device withstands electrostatic discharges exceeding 25kV, for increased reliability. The VPR221Z offers resistance values from 0.5? to 500?, and like all Vishay foil resistors, can be manufactured with any resistance value within the given resistance range without influencing cost or lead time. Featuring the TO-220 package, the device is offered with Pb-free and tin/lead alloy finishes, and is available in a surface-mount version, the VPR221SZ.

Typical applications for the resistor will include DC/DC converters, switching and linear power supplies, precision current sensing, feedback circuits, and precision amplifiers in test and measurement instrumentation, medical systems, satellites and aerospace systems, commercial and military avionics, and weapons systems.

Both the VPR221Z and VPR221SZ ultrahigh-precision resistors are available now, with lead times of 72 hours for samples, and three weeks for standard orders.

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