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Tue, March 15, 2011Mon, March 14, 2011Fri, March 11, 2011Thu, March 10, 2011Wed, March 9, 2011Tue, March 8, 2011Mon, March 7, 2011Sun, March 6, 2011Sat, March 5, 2011Fri, March 4, 2011Thu, March 3, 2011Wed, March 2, 2011Tue, March 1, 2011Mon, February 28, 2011Sun, February 27, 2011Fri, February 25, 2011Thu, February 24, 2011Wed, February 23, 2011Tue, February 22, 2011Mon, February 21, 2011Fri, February 18, 2011Thu, February 17, 2011Wed, February 16, 2011Tue, February 15, 2011Mon, February 14, 2011Sun, February 13, 2011Fri, February 11, 2011Thu, February 10, 2011Wed, February 9, 2011Tue, February 8, 2011Mon, February 7, 2011Sat, February 5, 2011Fri, February 4, 2011VPG Releases New Ultra-High-Precision Z-Foil Surface-Mount Current Sensing Chip Resistor With High Power Rating of 1 W, Low TCR
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Published in House and Home on Wednesday, February 23rd 2011 at 8:10 GMT by Market Wire🞛 This publication is a summary or evaluation of another publication
MALVERN, PA--(Marketwire - February 23, 2011) - Vishay Precision Group, Inc. (
The VCS1625ZP features a wide resistance range from 0.3 to 10 ohms. Vishay foil resistors are not restricted to standard values and specific "as required" values (e.g. 1.234 ohms vs. 1 ohm) can be supplied at no extra cost or delivery time. The resistor features a rise time of 1.0 ns, with effectively no ringing, short time overload of less than 0.005% (50 ppm), current noise of 0.010 microvolts RMS per volt of applied voltage (less than -40 dB), and a voltage coefficient of less than 0.1 ppm/V. Offering the utmost in ESD immunity, the device withstands electrostatic discharges at least to 25 kV for increased reliability, and offers a non-inductive (less than 0.08 microhenries), non-capacitive design. The VCS1625ZP can be offered with gold terminations and with additional temperature treatments to extend the operating temperature from +150° C to well above +220° C.
The Z-Foil technology of the VCS1625ZP provides a significant reduction of the resistive component's sensitivity to ambient temperature variation (TCR) and applied power changes (PCR -- "resistance change due to self-heating"), allowing designers to guarantee a high degree of stability and accuracy in fixed-resistor applications. The resistor's load-life stability to 0.02% (200 ppm) at +70° C for 2,000 hours at rated power is an order of magnitude better than typical current sensing resistors (0.5% for 1,000 hours). The device's improved stability makes it ideal for tightened-stability reference voltage and precision current sensing applications in forced-balance electronic scales, measurement instrumentation, bridge networks, and medical and test equipment. In addition, the VCS1625ZP complies with EEE-INST-002 (MIL-PRF 55342) for military and space applications.
The resistor's design results in a very low thermal EMF of 0.05 microvolts/°C typical, which is critical in precision applications. The VCS1625ZPS's all-welded construction is composed of a Bulk Metal® Foil resistive element with plated copper terminations. The flattened terminations make intimate contact with the resistive layer along the entire side of the resistive element, thereby minimizing temperature variations. In addition to the low thermal EMF compatibility of the device's metals, the uniformity and thermal efficiency of the design minimize the temperature differential across the resistor, thereby assuring low thermal EMF generation at the terminations. This further reduces the thermal EMF voltage, or "battery effect," exhibited by most current sensing or voltage reference resistors.
The stability problems associated with analog circuits are very pervasive, but the selection of a few high-quality current sensing resistors in critical locations can greatly improve circuit performance. Selection of a high-stability component like VCS1625ZP in these applications eliminates the need for shift allowance due to "planned instability," and allows the use of looser initial tolerances than would be necessary with current sensing resistors based on other technologies.
Many analog applications require performance under unusually high-stress conditions over extended periods of time. This calls for more than just selecting a standard device and applying it to a circuit. The standard device may turn out to be all that is needed, but an analysis of the projected service conditions should be made, and it may well dictate a routine of stabilization known as post manufacturing operations, or PMO. The PMO operations that will be discussed are only applicable to Bulk Metal Foil resistors. Short time overload, accelerated load life, and temperature cycling are the three PMO exercises that do the most to remove service life anomalies. VPG's Bulk Metal Foil resistors are inherently stable as manufactured, but these PMO exercises may improve performance by small but significant amounts. Users are encouraged to contact Vishay Foil Resistors' applications engineering team for assistance in choosing the PMO operations that are right for their applications.
When current sensing has important implications -- such as force-balance electronic scales measuring valuable gems or pharmaceuticals, or to control the guidance of missiles with electro-static gyros -- the current represents system conditions where errors have extremely serious consequences. These systems don't just measure digitally significant on/off stages. Their continuously changing analog outputs in current mean the sense resistors are constantly changing their power dissipation, which in turn changes their operating temperatures independently of ambient temperature. Therefore, the inherent TCR of the sense resistors registers constantly changing resistance and present current sensing errors superimposed upon the current that would represent the real current output of the main analog sensors. One way to eliminate these errors, though expensive, is to develop a correction factor for each individual piece of sensing equipment. A more practical way is to use very-low-TCR current sense resistors, such as the VCS1625ZP, that isolate the current output from varying power dissipation effects.
The devices released today are characterized by extremely low excess noise when compared to other types of resistors. Additionally, the current in adjacent current-carrying paths runs in opposing directions, canceling the parasitic inductance of these paths. Also, path-to-path capacitances are connected in series, which has the effect of minimizing the parasitic capacitance of the resistor. These low-inductance/capacitance resistors are characterized by non-measurable peak-to-peak signal distortions.
Samples and production quantities of the VCS1625ZP are available now, with lead times of five working days for samples and six weeks for standard orders.
Further information about the VCS1625ZP and other Vishay Foil Resistors products is available at [ www.vishayfoilresistors.com ]. Follow Vishay Foil Resistors at [ http://twitter.com/VPGFoil ].
About Vishay Foil Resistors
Vishay Foil Resistors is a division of Vishay Precision Group, producing the most precise and stable type of resistors available. The 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. The 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 (VPG) produces sensors based on precision resistive foil technology, and sensor-based systems. It provides 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, VPG's decades-long track record encompasses innovations in foil precision resistors, current sensors, and strain gages, which have served as a foundation for VPG's 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 ].
Note to editors: This release is from Vishay Precision Group, which is a separate company from Vishay Intertechnology. If you need to shorten the company name after the first reference, please use the abbreviation "VPG" rather than "Vishay."
Link to product datasheet:
[ http://www.vishaypg.com/doc?63155 ] (VCS1625ZP)
Link to product photo:
[ http://www.flickr.com/photos/47034298@N02/5456503539/ ]
