Precision resistors - 18 August 2010 - Future Electronics

Vishay has announced a new series of high-precision Bulk Metal Z-Foil resistors built using Z1-Foil technology that features enhanced accuracy, stability and fast thermal stabilisation in sizes small enough for permanent assembly in operational equipment.

The SMR3P devices feature a TCR of ±0,5 ppm/°C maximum (+25°C to

+125°C), tolerances to 0,01%, load-life stability of ±0,005% (50 ppm) after 10 000 hours with 0,6 W at 70°C, and PCR (ΔR due to self-heating) of ±5 ppm at a rated power of 0,6 W at +70°C or 0,3 W at +125°C.

The SMR3P series is targeted at 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 moulded 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 resistors 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 SMR3P series features electrostatic discharge (ESD) immunity up to 25 000 V, a thermal stabilisation time of <1 second (nominal value achieved within 10 ppm of steady-state value), current noise of 0,010 μV_RMS/V of applied voltage (<-40 dB) and a voltage coefficient of <0,1 ppm/V. The 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 (eg, 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-free or tin/lead alloy terminal finishes.

For more information contact Marian Ledgerwood, Future Electronics, +27 (0)21 421 8292, marian.ledgerwood@futureelectronics.com, www.futureelectronics.com