VPG aims metal foil resistors at 4-20mA loops

05jun13VPGcurrentLoop 417For the instrument end of 4-20mA current loops, Vishay Precision Group is marketing its range of precision metal foil resistors.

At this point, 4-20mA has to be measured, typically by converting it to 1-5V using a 250Ω resistor, said VPG.

“The surface-mount VSMP series and through-hole Z series devices offer a temperature coefficient of +/-0.05ppm/°C typical from 0 to +60°C, and +/-0.2ppm/°C typical from -55°C to +125°C, referred to 25°C,” said the firm.

Inductance is below 0.08μH, rise-time is 1ns, and thermal stability to 10ppm is under 1s.

Current noise is <0.010µVrms/applied volt (<-40dB), voltage coefficient is <0.1ppm/V, and a thermal EMF of 0.05μV/°C is typical.

For even more precision, the firm offers VHP100 resistors with “essentially zero” temperature coefficient and tolerances down to ±0.005% (50 ppm).

The firm has released an application note on 4-20mA current loops.

Tags: precision group, surface-mount, temperature coefficient, thermal stability

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