Vishay Precision Group (Malvern, PA) has announced that its Vishay Foil Resistors brand (VFR) has released new ultra-high-precision Z-Foil power current sensing resistors for applications where rapid ΔR stabilization and resistance stability under transient power conditions are required. Designed to provide optimal performance when mounted on a chassis or cooled heat sink, the VCS331Z, VCS332Z, VFP4Z, and CSNG Series feature low TCR of ±0.2 ppm/°C from -55°C to +125°C, +25°C ref., PCR (ΔR due to self-heating) of 4 ppm/W typical, and tolerances to ±0.01%. For high-power applications, the devices offer power ratings up to 10 W (on heatsink) and a four-terminal Kelvin configuration in order to remove the unwanted influence of lead resistance and lead sensitivity to temperature. Features include:

  • Load-life stability to ±0.005% typical (50 ppm) at 3 W (heat sink) and +25°C for 2,000 hours.
  • Thermal stabilization time of <1 s (within 10 ppm of steady state value).
  • Wide resistance range of 0.25 Ω to 500 Ω.
  • Rise time of 1.0 ns with effectively no ringing.
  • Current noise of 0.010 µVrms/V of applied voltage (<-40 dB).
  • Voltage coefficient of <0.1 ppm/V.

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