Power Electronics

High-Precision Z-Foil Surface-Mount Current Sensing Chip Resistor

Vishay Precision Group, Inc. announced that its Vishay Foil Resistors (VFR) brand has introduced a high-precision Z-Foil surface-mount current sensing chip resistor with low TCR of ±0.2 ppm/°C typical from -55°C to +125°C, +25°C ref., tolerances to ±0.5%, and load-life stability to ±0.015% at 70°C 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 (Delta R due to self-heating) of 5 ppm at rated power and a four-terminal Kelvin configuration for increased accuracy.

The VCS1610Z offers a power rating of 0.25 W at +70°C, thermal stabilization time of <1 s (nominal value achieved within 10 ppm of steady state value), and resistance range from 0.3 ohms to 10 ohms. 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 1.0 ns with effectively no ringing, short time overload of <0.005%, current noise of 0.010 µVrms/V of applied voltage (<-40 dB), and a voltage coefficient of <0.1 ppm/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 25 kV for increased reliability and offers a non-inductive (<0.08 µH), 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 0.05 µV/°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.

Samples and production quantities of the VCS1610Z are available now, with lead times of five working days for samples and eight weeks for standard orders. Pricing for U.S. delivery starts at $4.48.

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