Vishay’s SMR3P Ultra-High-Precision Resistors Feature Tolerance to 0.01 %, Maximum TCR of ± 0.5 ppm/°C, and Load-Life Stability of ± 0.005 % (50 ppm) After 10,000 Hours with 0.6 W at + 70 °C

Vishay’s SMR3P series offers an immediate answer to many resistor applications currently believed unsolvable, including secondary standards, feedback devices for operational amplifiers, precision voltage dividers, precision bridge resistors, and decade voltage dividers in precision amplifiers; high-precision instrumentation; medical, industrial, high-end stereo, and automatic test equipment; electron beam and pulse applications; and measurement instrumentation.

Chips of 1206 and larger dimensions occasionally delaminate from the PCB or develop cracks due to the stresses introduced by handling of the PCB and thermal shock. The SMR3P features a molded package with flexible terminations that ensure minimal stress transference from the PCB due to load-induced temperature gradients and a difference in thermal coefficient of expansion (TCE).

The SMR3P’s low absolute TCR reduces errors due to temperature gradients, thus reducing a major source of uncertainty in precision circuits. The SMR3P can withstand unconventional environmental conditions, including the extremely high temperatures and radiation-rich environments of down-hole oil exploration and well logging, or the deep-sea underwater repeaters in cross-ocean communications.

The Bulk Metal Z-Foil resistor has documented the most precise load-life stability of any resistor due to a unique concept in resistor manufacturing. A proprietary new generation of the Bulk Metal Z-Foil element with known and controllable properties is applied to a special ceramic substrate. A resistive pattern is then photoetched by an ultra-fine technique developed by Vishay. The device’s etched planar construction results in the extremely low and reproducible reactance needed for high-frequency and pulse applications. The resistor’s controlling physics combine an unaltered bulk alloy with a unique balance of known and controllable forces to provide the lowest TCR and the best long-term stability of any available resistor.

The resistors released today feature electrostatic discharge (ESD) immunity up to 25,000 V, a thermal stabilization time of < 1 seconds (nominal value achieved within 10 ppm of steady-state value), current noise of 0.010 µVRMS/V of applied voltage (< - 40 dB), and a voltage coefficient of < 0.1 ppm/V.

The SMR3P devices offer a resistance range of 100 Ω to 15 kΩ. Vishay Foil resistors are not restricted to standard values, and can be supplied with “as required” values (e.g. 1.0002 kΩ vs. 1 kΩ) at no extra cost or delivery time. The resistors offer a non-inductive (< 0.08 µH), non-capacitive design, and feature lead (Pb)-free or tin/lead alloy terminal finishes.