Vishay Precision Group has announced that its VFR (Vishay foil resistors) division has released a high-precision foil surface-mount current sensing chip resistor with a TCR (temperature coefficient of resistance) of ±2ppm/°C from -55 to +125°C, 25°C reference, and tolerances to ±0.1%; 0.01% and 0.05% are also available. The VCS1625P offers a power rating of 1W at 70°C and maximum 5A current rating, and a four-terminal Kelvin configuration for increased accuracy, claims the company.
The resistor features a resistance range from 0.01 to 10Ω, with specific values within the range of 1.234 versus 1Ω. According to the company, the resistor features a rise time of 1ns, with effectively no ringing, short time overload of less than 0.005% or 50ppm, current noise of 0.010µVrms/V of applied voltage which is more than or equal to 40dB, and a voltage coefficient of less than 0.1ppm/V. The resistor is available with tin and lead or lead-free gold or tin termination options, and with additional temperature treatments to extend the operating temperature from 150 to over 200°C.
The bulk metal foil technology of the resistor minimises the resistive component's sensitivity to ambient temperature variation of TCR and to the self-heating effect caused by changing loads. The resistor is suitable 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 resistor can be tested in accordance with EEE-INST-002 or MIL-PRF 55342 for military and space applications.
The resistor's design results in a low thermal EMF (electromotive force) of 0.05 μV/°C. The resistor'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 minimising temperature variations, says the company. 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 minimising the parasitic capacitance of the resistor. The resistor is characterised by non-measurable peak-to-peak signal distortions.
