VPG – High-precision Z-Foil surface-mount current-sensing chip resistor (VCS1610Z)Jul 19 2012 - Passives [More Passives Articles]
Vishay Precision Group (VPG) has announced that its Vishay Foil Resistors (VFR) group has introduced a high-precision Z-Foil surface-mount current-sensing chip resistor with low TCR of ±0.2 ppm/C typical from -55C to +125C, +25C ref., tolerances to ±0.5%, and load-life stability to ±0.015% at 70C for 2,000 hours at rated power.
Ideal for current measurement in unconventional environmental conditions, including the extremely high temperatures and radiation-rich environments of down-hole oil exploration and well logging, or the deep-sea underwater repeaters in cross-ocean communications, the VCS1610Z features PCR (ΔR due to self-heating) of 5ppm at rated power and a four-terminal Kelvin configuration for increased accuracy.
The VCS1610Z offers a power rating of 0.25W at +70C, thermal stabilization time of <1s (nominal value achieved within 10ppm of steady state value), and resistance range from 0.3ohm to 10ohm. Any resistance value within this range is available at any tolerance with no additional cost or lead time effect. The resistor features a rise time of 1ns with effectively no ringing, short time overload of <0.005%, current noise of 0.01µVrms/V of applied voltage (<-40dB), and a voltage coefficient of <0.1ppm/V. The VCS1610Z is available with lead (Pb)-free gold or tin/lead termination options.
Providing the utmost in ESD immunity, the device withstands electrostatic discharges to at least 25kV for increased reliability and offers a non-inductive (<0.08μH), non-capacitive design. The Bulk Metal Z-Foil technology of the VCS1610Z provides a significant reduction of the resistive component’s sensitivity to ambient temperature variations (TCR) and applied power changes (PCR). This allows designers to guarantee a high degree of stability and accuracy in fixed-resistor applications. In addition, the resistor’s design results in a very low thermal EMF of 0.05μV/C typical, which is critical in low-ohmic current sensing resistors used in DC circuits.
In order to select the resistor technology most appropriate to their applications, designers must take into account all normal and extraordinary stresses the resistor will experience. In addition, they must consider the impact, in terms of cost and reliability, when it becomes necessary to add additional compensating circuitry when inadequate resistors are selected. The stability of Bulk Metal Z-Foil resistors, as well as the other basic advantages apparent in their specifications, will not only provide unequalled performance in the circuit, but also will eliminate all the costs associated with extra compensation circuitry. With the VCS1610Z, 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, says the company.
“The physics of the Bulk Metal resistor are fairly simple to describe, but the realization of a foil resistor requires advanced expertise in multiple disciplines. These include metallurgy; high-temperature adhesives; very fine-line photolithography; fine etching and passivation; conductor path design; stress analysis and its thermal components; strain-relieving encapsulates and terminations; and much more,” said Yuval Hernik, senior director of application engineering, Vishay Foil Resistors.
In addition, Mr. Hernik cautioned that, as with all purchases of precision electronics in today’s world, buyers must be vigilant in order to prevent unreliable counterfeit resistors from entering their warehouses and electronic systems. “It is unfortunate that fraud has penetrated the electronics industry. But this is a fact we all have to live with, and our only protection is unremitting vigilance and purchasing only from VFR or its authorized distributors and catalogue houses.”
Samples and production quantities of the VCS1610Z are available now, says the company.More news from Vishay Precision Group