Vishay's New VPR221Z Ultra-High-Precision Z-Foil Resistor

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

The new VPR221Z resistor is built on Vishay's "Z- Foil" technology, which provides a significant reduction of the resistive components sensitivity to ambient temperature variations (TCR) and applied power changes (PCR). 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.

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 1.0-ns 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% (50ppm) for 2000 hours at +25°C; a low voltage coefficient of <0.1PPM/V; current noise of <-42dB; and thermal EMF of 0.05μV/°C. The resistor features a non-inductive (<0.08μH), non-capacitive design, and a 4-Kelvin connection for increased accuracy.

Offering the utmost in ESD immunity, the device withstands electrostatic discharges exceeding 25kV, for increased reliability. The VPR221Z offers resistance values from 0.5Ω to 500Ω, 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 lead (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-to-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.

Vishay Intertechnology