Z-Foil VAR

By Vishay Foil Resistors (Division of Vishay Precision Group) 305

Z-Foil VAR

Vishay Foil Resistors has announced the expansion of its high-end audio application portfolio with the release of the enhanced ultra-high-precision Z-Foil VAR. Based on bulk metal foil technology, the new devices are specifically designed to minimize the self-inductance and capacitance inherent in all resistors, offering improvements in sound quality by reducing audible distortion. The devices are optimized for use in loudspeaker crossover assemblies, audio power amplifiers, and instrumentation amplifiers.

The company has enhanced the ultra-high-precision Z-Foil VAR resistor to offer low TCR down to 0.05 ppm/°C typical from 0°C to +60°C, 25°C ref, tolerances down to ±0.005%, and load-life stability to ±0.005% (50 ppm) at 70°C for 2,000 hours at rated power. The device has been bolstered with a thermal stabilization time of <1 s (nominal value achieved within 10 ppm of steady state value) and can operate at higher frequencies.

The VAR provides a combination of low noise, low inductance / capacitance, and improved thermal response, making it unrivalled for applications requiring distortion-free properties. Its special 'naked Z-foil resistor' design, without molding or encapsulation, adds an additional dimension for reducing signal distortion and increasing clarity in signal processing.

  • Temperature coefficient of resistance (TCR): ± 0.05 ppm/°C typical (0°C to 60°C, 25°C ref.) ± 0.2 ppm/°C typical (0°C to 125°C, 25°C ref.)
  • Rated power: to 0.4 W at 70°C
  • Resistance tolerance: to ± 0.01 % (0.005% is available)
  • Resistance range: 10 Ω to 100 kΩ
  • Electrostatic discharge (ESD) at least to 25,000 V
  • Non-inductive, non-capacitive design
  • Terminal finish: lead (Pb)-free or tin/lead alloy
  • Rise time: 1 ns, effectively no ringing
  • Current noise: 0.010 µV (RMS)/Volt of Applied Voltage (< -40 dB)
  • Thermal EMF: 0.05 µV/°C
  • Voltage coefficient: < 0.1 ppm/V
  • Thermal stabilization time < 1 s (nominal value achieved within 10 ppm of steady state value)
  • Inductance: < 0.08 μH typical
  • Load life stability: to ± 0.005 % at 70°C, 2000 h at rated power