a-High-Precision Foil Surface-Mount Current Sensing Chip Resistor With High Power Rating of 1 W, Low TCR to ±2 ppm/°C, Load Life Stability of 0.015% (2,000 hours, +70°C), and Tolerances to ±0.1%.
The VCS1625P features a wide resistance range from 0.01 Ω to 10 Ω, with specific as required values within this range (e.g. 1.234 Ω vs. 1 Ω) available at no additional cost or delivery time. The resistor features a rise time of 1.0 ns, with effectively no ringing, short time overload of <0.005% (50 ppm), 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 electrostatic discharge (ESD) immunity, the device withstands ESD to at least 25 kV for increased reliability, and offers a non-inductive (<0.08 μH), non-capacitive design. The VCS1625P is offered with tin/lead or lead (Pb)-free gold or tin termination options, and with additional temperature treatments (PMO) to extend the operating temperature from +150°C to well above +200°C. The design of the VCS1625P allows for designers to use only a single device to measure larger currents than previously possible by dissipating up to 1 W in the same 1625 size package.
The Bulk Metal® Foil technology of the VCS1625P provides a significant reduction of the resistive component's sensitivity to ambient temperature variation (TCR) and to the self-heating effect caused by changing loads. These capabilities allow designers to guarantee a high degree of stability and accuracy in fixed-resistor applications. The resistor's load-life stability at +70°C at rated power is an order of magnitude better than typical current sensing resistors (0.015% after 2,000 hours versus 0.05% after 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, motor controllers, and medical and test equipment. In addition, the VCS1625P can be tested in accordance 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 μV/°C typical, which is critical in precision applications. The VCS1625P's all-welded construction is composed of a Bulk Metal Foil resistive element with plated copper terminations. The flat 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 device released today is characterized by extremely low excess noise when compared to other resistor technologies. Additionally, the current in adjacent current-carrying paths runs in opposing directions, cancelling 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. The low-inductance/capacitance VCS1625P resistor is characterized by non-measurable peak-to-peak signal distortions.