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MALVERN, PENNSYLVANIA Nov. 8, 2010 Vishay Precision Group, Inc. (NYSE: VPG) today announced that its Vishay Foil Resistors division has released a new ultra-high-precision Z-Foil power current sensing resistor with low TCR of ±0.05 ppm/°C from 0°C to +60°C and ±0.2ppm/°C from -55°C to +125°C, +25°C ref., power TCR (PCR) of 4 ppm/W typical at rated power, tolerances to ±0.02%, and load life stability to ±0.005% (50 ppm) at +25°C for 2,000 hours at rated power. For high-power applications, the VCS232Z
offers a power rating of 2 W (free air) at +25ºC.
features a wide resistance range from 0.25 Ω to 500 Ω. Vishay Foil resistors are not restricted to standard values and specific “as required” values (e.g. 100.234 Ω vs. 100 Ω) can be supplied at no extra cost or delivery time. The resistor features a rise time of 1 ns, with effectively no ringing, thermal EMF of 0.05 μV/°C typical, a thermal stabilization time of <1 s (nominal value achieved within 10 ppm of steady-state value), current noise of 0.010 μVrms/V of applied voltage (<-40 dB), and a voltage coefficient of <0.1 ppm/V. Offering the utmost in ESD immunity, the device withstands electrostatic discharges up to at least 25 kV, for increased reliability, and offers a non-inductive (<0.08 µH), non-capacitive design.
The power current sensing resistor released today is designed to improve performance by directly replacing wirewound resistors for pulse and current sensing applications in automatic test equipment, high-precision instrumentation, electron beam applications, power amplifiers, power supplies, and military and medical equipment. Today, designers of analog circuits are demanding discrete power current sensing resistors that approach the ideal in performance. They require stable, high-speed, high-accuracy components that will operate with assured, predictable reliability for years in a variety of environments. The Z-Foil resistor meets those demands with unequalled performance.
Four fundamental factors determine how “ideal” a precision power current sense resistor will be: initial resistance value; how precisely the value of individual resistors can be maintained; how precisely the end-of-life tolerance is maintained under a wide range of operating conditions and stress factors; and fast response time without ringing and fast thermal stabilization. Until the development of Foil resistors, precise control of all four factors was virtually impossible.
resistor, containing the latest Z-Foil technology, achieves maximum stability, a near-zero temperature coefficient, and the ability to remove errors due to temperature gradients. This superior performance is built-in for every unit and does not rely on culling or other artificial means for uniform excellence. The stability of Vishay Foil resistors allows designers to eliminate other passive components and costly corrective circuitry. With the VCS232Z
, only a minimal shift in resistance value will occur during its entire lifetime. Most of this shift takes place during the first few hundred hours of operation, and virtually no change is noted thereafter.
Current sensing is best achieved with a Kelvin connection, as featured with the VCS232Z
, which removes the unwanted influences of lead resistance and lead sensitivity to temperature. A Kelvin connection reduces, especially for low ohmic resistance values, a measurement error due to the resistance of the lead wires and the solder joints as the sensing is performed inside the resistor, in or close to the active resistive bulk metal foil element.
has a low thermal EMF, which is directly attributed to the special design of the device. Thermal EMF results from the thermocouple effect which exists between dissimilar metals. Under normal conditions, the voltage generated in one lead is cancelled by that of an equal and opposite polarity in the other lead. When a temperature differential exists between the two leads, a voltage difference will occur between.
Offered with lead (Pb)-free or tin/lead alloy terminations, and compliant to RoHS Directive 2002/95/EC, samples and production quantities of the VCS232Z
are available now, with lead times of five days for samples, and eight weeks for standard orders.
About Vishay Foil Resistors
Vishay Foil Resistors is a division of Vishay Precision Group, producing the most precise and stable type of resistors available. Our portfolio comprises products in a variety of resistor configurations and package types to meet the needs of a wide range of applications: discrete resistors and resistor networks in surface mount and through-hole (leaded) configurations; customized chip resistor networks; precision trimming potentiometers; and discrete chips for use in hybrid circuits. Our foil resistors and current sensors are used in applications requiring a high degree of precision and stability, such as in medical testing equipment, high performance audio equipment, precision measuring instruments and aerospace and military applications.
About Vishay Precision Group
Vishay Precision Group produces sensors based on precision resistive foil technology, and sensor-based systems. We provide vertically integrated products and solutions for multiple growing markets in the areas of stress, force, weight, pressure and current measurements. As a spin-off from Vishay Intertechnology, our decades-long track record encompasses innovations in foil precision resistors, which we invented, current sensors, and strain gages, which have served as a foundation for our more recent expansion into strain gage instrumentation, load cells and transducers, weighing modules and complete systems for process control and on-board weighing. Vishay Precision Group may be found on the Internet at www.vishaypg.com