Electronic Design

Resistors, Capacitors

Capacitors Provide High-Capacity Storage With Long Service Life
North American Capacitor Co.
(317) 273-0090; fax (317) 273-2400; www.nacc-mallory.com

The Type MEC electrochemical capacitors bridge the performance gap between batteries and capacitors to provide high-capacity storage with long service life. The devices require low maintenance. According to the company, these capacitors can be used to augment or replace batteries. Since the ca-pacitors are modular in de-sign, virtually any number of cells can be combined to meet the needs of specific applications. Applications fall into three broad categories: engine starting, traction power, and load leveling. Devices for engine-starting applications are available in both polar and nonpolar configurations. While nonpolar versions can be discharged down to 0 V, typical polar versions are available in both 12- and 24-V configurations. The energy density of the capacitors for traction power applications exceeds 10 Wh/kg. They are available with typical voltage windows ranging from 48 V/ 24 V to 160 V/ 80 V. MEC capacitors for load-leveling applications are generally custom configured. Pricing for the MEC capacitor line depends on the model, options, and quantity ordered. Contact the company for pricing and availability information.



Potentiometers Withstand High-Temperature Reflow Soldering
Murata Electronics
(770) 436-1300; fax (770) 436-3030; www.murata.com

Members of the PVG3 series are ultra-small closed cermet trimmer potentiometers. These devices can be utilized in the high peak-temperature lead-free reflow soldering process. This series offers two terminal shapes: J-lead (PVG3A) and Gull Wing (PVG3G). While the J-lead is recommended for new design applications, the Gull Wing lead terminal is used to replace trimmer potentiometers 4 mm in size. The chips can be cleansed in alcohol-based solvents. The driver plate is equipped with a cross-slot, suiting it for automatic adjustment. Soldering pads are available in 3- and 4-mm sizes. The terminals employ tin plating brass. Available now, the potentiometers cost $0.23.



Chip Attenuator Array Features Extended Attenuation Factor
Kamaya Inc.
(219) 489-1533; www.kamaya.com

Members of the RAC10 1A series of chip attenuator arrays are available in 18 attenuation factors ranging from 0.5 to 20 dB. This 1- by 1-mm surface-mount chip array delivers a 57% pc-board space savings compared to conventional attenuation circuits requiring three discrete resistors. The RAC10 1A is suited for use from dc to UHF. It is designed for signal-conditioning and impedance-matching circuits.

According to the manufacturer, the devices are ideal for wireless applications, including WLAN, digital phones, cordless phones, modems, pagers, audio equipment, and transmission amplifiers. This device offers an operating-temperature range of −40°C to 125°C. It features a rated input of 100 mW/package with an impedance of 50 Ω.

The RAC10 1A comes in 2-mm pitch paper-tape packaging. In 100,000-unit quantities, the arrays cost $25.00 per 1000.0



Termination Network Eases Use Of 266-MHz DDR Synchronous DRAMs
STMicroelectronics Inc.
(781) 861-2650; www.st.com

The DDR110-xxT7 is a chip-level 10-resistor network. It allows designers to take advantage of the latest 266-MHz double data-rate (DDR) synchronous DRAMs mounted on dual in-line memory modules (DIMMs). This network saves sparse motherboard space by eliminating termination cards. Also, the DDR110-xxT7 automatically disconnects its termination resistors when socketing slower single data-rate (SDR) DIMMs.

The DDR110-xxT7 works with PC100, PC133, PC1600, and PC2100 DIMMs. It serves as a companion device for the Aladdin Pro 5 and the ALiMAGiK1 system chip sets from ACER Labs. It is also compatible with Silicon Integrated Systems' SIS635(T) and SIS735 and VIA Technologies' Apollo PRO266 and Apollo KT266. Each of the DDR110-xxT7's 10 termination resistors includes a switch. These switches are controlled in unison by the chip's TTL-compatible output-enable (OE) signal line. The chip is available with termination resistor values of 27 and 56 Ω. It comes in a 24-pin TSSOP with a 0.65-mm pin pitch. In 500,000-unit quantities, the chip costs $0.35 each.



Pulse-Withstanding Chip Resistors Achieve Significant Power Ratings
International Resistive Co. Inc.
(361) 992-7900; fax (361) 992-3377; www.irctt.com

The PWCR series resistors are available in four standard sizes—0805, 1206, 2010, and 2512— and feature power ratings from 0.125 to 1.5 W at 70°C. According to the company, these thick-film pulse-withstanding chip resistors achieve significant power ratings in a limited space. The pulse-withstanding capability of the PWCR series ranges up to 5 kV for a 2512-size resistor with 1.2/50-µs and 10/700-µs pulse shapes as defined by IEC 60-115-1. The devices feature an increased limiting element voltage (LEV) of 150 V for the 0805 size and 500 V for the 2512 size.

According to the company, the enhanced performance of these resistors is achieved by the use of special thick-film inks. A specially developed production process is also employed. The PWCR series resistors suit line-protection applications in telecommunications equipment. They can also be employed as surge-withstanding resistors for use in power circuit breakers. For pricing and availability information, contact the company.



Single-Chip Termination And Filtering Solution Offers High ESD Protection
California Micro Devices Corp.
(408) 263-3214; fax (408) 263-7846; www.calmicro.com

The PACUSB-U1/U2/U3 is a USB termination and filtering product for use in PDAs, two-way pagers, and Internet appliances. This device is available in a six-pin SC70 package. The small form factor of this solution enables it to be used in products where board space constraint is a factor. The device employs the company's patented P/Active technology. The PACUSB-U1/U2/U3 provides EMI/RFI filtering, termination, and ESD protection that exceeds the IEC 61000-4-2 Level 4 specification. It is able to protect a PDA or Internet appliance from accidental damage caused by ESD up to 30 kV when tested to IEC 61000-4-2 specifications.

This device terminates the two data lines for the USB port. There are three series resistor values available to engineers to match it and the USB driver's resistance with the USB cable's impedance. Available R1 values include 15, 33, and 22 Ω for PACUSB-U1, PACUSB-U2, and PACUSB-U3, respectively. Available now, the PACUSB-U1/U2/U3 costs $0.30 each in 10,000-unit quantities.



Commercial SMPS Capacitors Suit I/O Filtering
AVX Corp.
(843) 946-0414; fax (843) 448-1943; www.avxcorp.com.

Members of the SE series of MLC capacitors are designed for input and output filtering in switchmode power supplies (SMPSs). The capacitors are radial-leaded and conformally coded. Available in X7R dielectric, these devices are specially processed to handle high currents. According to the company, these capacitors offer significant capacitance extension beyond the SK series' range. They are available in voltage ratings up to 100 V dc and capacitances range up to 39 µF. Also, the maximum CV rating of the SE series capacitors improves the volumetric efficiency by a factor of three beyond the ranges of the SK series.

The capacitors also can be used in bus filters and dc snubbers for high-power inverters and other high-current applications. While five standard sizes are offered, available voltage ratings include 25, 50, and 100 V dc. Operating-temperature range is −55°C to 125°C. Prices range from $0.78 to $6.15 in 1000-unit quantities, depending on size and value.

Hide comments

Comments

  • Allowed HTML tags: <em> <strong> <blockquote> <br> <p>

Plain text

  • No HTML tags allowed.
  • Web page addresses and e-mail addresses turn into links automatically.
  • Lines and paragraphs break automatically.
Publish