TAIPEI, Taiwan — Vishay Precision Group, Inc. today announced that its Vishay Foil Resistors brand (VFR) has extended its VTAZ series of Bulk Metal Z-Foil ultra-high-precision tubular axial-lead resistors with a new device in the RBR57 MIL size.
Designed to provide a direct replacement, with better performance, for wirewound and metal film devices, the VTA57Z features ultra-low TCR of ±0.05 ppm/°C nominal (0°C to +60°C) and ±0.2 ppm/°C nominal (-55°C to +125°C, +25°C ref.), and load-life stability of less than ±0.005% after 2,000 hours of rated power at 70°C.
Tested to EEE-INST-002 guidelines for critical space applications, the VTA57Z offers high power ratings of 0.25 W at +70°C and a 160 V maximum working voltage. The device features a wide resistance range from 5 Ω to 100 kΩ, with tight resistance tolerance to ±0.01%. Any conceivable ohmic value within this range, to six digits, is available with no additional cost or lead time effect.
Compared with wirewound and metal film resistors, Bulk Metal Foil resistors operate at higher frequencies with higher speed, lower inductance, lower capacitance, and smaller phase angles, in addition to providing higher power density, lower TCR, better load-life stability, and lower current noise.
Harmonic distortion is another important consideration in the choice of precision resistors for precision applications because a significant signal voltage may change the resistance value. Under these conditions, Bulk Metal Foil resistors behave more linearly than other resistor technologies.
Foil resistors are available in both axial-lead and chip configurations, and they can be switched from one to the other with no electrical redesign required. Wirewound devices, by contrast, are not available in the chip format used in most assembly processes.
“Another disadvantage of wirewound devices is that TCR tracking is especially difficult with resistors of unequal values,” said Yuval Hernik, senior director of application engineering for VFR. “For an extra cost, the same values can be selected for TCR tracking, but the devices must be packaged and handled with extreme care to avoid mixing.”
Samples and production quantities of the new Bulk Metal Foil resistor are available now, with lead times of five working days for prototype samples and eight weeks for standard orders.
