Review

With increasing frequency, new passive components are arriving in the marketplace lead-free, as the industry moves to rid electronic products of lead and the health problems associated with the metal. This trend spans the entire panoply of passives found today on new pc boards: from resistors and capacitors to protective and filtering devices. With electronic products continuing to shrink in size, especially portables and handhelds, the size of passive components naturally follows suit, giving rise to new, smaller form-factors. Significant advances are also being made in the performance of passives. Here are several new products introduced in EEPN over the last 12 months that underscore these trends.

Compliance with worldwide lead-free manufacturing standards and tolerance of the 260°C ambient temperatures used in lead-free soldering operations are the claims made for Littelfuse's (littelfuse.com) 467 Series of SlimLine SMT fuses . Targeting applications requiring over-current protection, the new, 0603 size, very fast acting fuses use no lead in either their fusing element or termination, which are composed of 100% copper/nickel/tin.

Another lead-free passive that entered the market this year is Tyco Electronics's (tycoelectronics.com) DXM series power inductors . The devices are used for collecting, filtering and smoothing AC ripple current in dc circuits, such as found in switching power supplies and portable electronics. The miniature, 13 mm x 13 mm x 6 mm power inductors have current handling ranges of up to 30A and inductance ranges of 0.2 to 10 µH.

Many new passives made their mark in the marketplace through miniaturization, with three of the more interesting being: Taiyo Yuden's (t-yuden.com)RM series of multi-layer ceramic capacitors (MLCCs) having a miniscule, 0201 case size; Micro Crystal's (mcrystal.com) CC7V-T1A miniature, 3.2 mm x 1.5 mm x 0.85 mm high tuning fork crystal; and Vishay BCcomponents's (vishay.com) 158 PUL-SI snap-in, ultra-long-life aluminum electrolytic capacitors spanning case sizes of from 22 mm in diameter x 25 mm high to 35 mm x 50 mm and capacitance values from 560 to 47,000 µF.

Passive makers also chalked up a number innovations, with one of the most interesting being Vishay Intertechnology's (vishay.com) HPC-0402A, a silicon-based SMT capacitor that is said to bring the cap's self-resonance frequency (SRF) into the ultra-high region. The 0402-size, high-performance RF capacitor spans a 0.6 to 180 µF capacitance range with tolerance to ±1%, comes in 6V, 10V, 16V and 25V models, reduces board real estate requirements by up to 45%, and also reduces parasitic inductance.

By packing three low-temperature-coefficient digital resistors with 128 user-selectable positions per resistor into an 8-lead microSOP, Dallas Semiconductor (maxim-ic.com) has developed a device for use in automated power supply calibration circuits. The DS3904 non-volatile digital resistor operates from a 2.7V to 5.5V supply and communicates via a two-wire serial interface. Typical resistance range for each resistor is 425Ω to 20 kΩ.

Other novel products include Analog Device's AD5273 one-time-programmable digital trimmer with a 64-step resolution (analog.com) and Tyco Electronics's GB4xxx-LP single-port Gigabit Ethernet module housing four isolation transformers and four common mode chokes.

—Joe DelGatto

Outlook

New Passives Set Sights On Niches
Many of the developments forecasted for passive components are expected to occur on two fronts: niche application areas and modular products. Among the niches expected to benefit from passive manufacturers' new product R&D efforts are wireless and other telecomm products, automotive and power supplies of all sizes. And when it comes to modularization, look to manufacturers to cram more and more discrete devices into ever smaller modules and networks. Silicon-based passives are also expected to undergo considerable growth, due largely to products now under development. And, of course, advancements will continue to be made in lead-free designs and miniaturization of all types of passive components.

—JDG