Vishay Precision Group has released a new high-precision surface-mount current sensing chip resistor with low TCR of ±2 ppm/°C from -55°C to +125°C, +25°C ref., and tolerances to ±0,1% (0,01% and 0,05% are available). For high-power applications, the VCS1625P offers a power rating of 1 W at +70°C and maximum 5 A current rating, and a four-terminal Kelvin configuration for increased accuracy.
The resistor 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%, current noise of 0,010 μVrms/V of applied voltage (< -40 dB), and a voltage coefficient of <0,1 ppm/V.
The device withstands ESD to at least 25 kV for increased reliability, and offers a non-inductive (<0,08 H), non-capacitive design. It is offered with tin/lead or lead-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 resistor’s load-life stability at +70°C at rated power is 0,015% after 2000 hours.
This 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 V/°C typical, which is critical in precision applications. In addition to the low thermal EMF compatibility of the device’s metals, the uniformity and thermal efficiency of the design minimise 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 is characterised by very 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 minimising the parasitic capacitance of the resistor.
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