Capacitors And Potentiometers

March 5, 2001
Ultracapacitor Powers System For Peak Loads And Outages As a 2500-F ultracapacitor, the PC2500 suits industrial, UPS, hybrid-electric vehicle, and fuel-cell applications. Also, it may be used for any other...
Ultracapacitor Powers System For Peak Loads And Outages As a 2500-F ultracapacitor, the PC2500 suits industrial, UPS, hybrid-electric vehicle, and fuel-cell applications. Also, it may be used for any other application requiring pulsed power, high cycle reliability, and low maintenance.

This device caches 7800 J of energy at a nominal 2.5 V for high-powered discharges from fractions of a second to one minute. It provides roughly 10 times the power density of ordinary batteries alone. This ultracapacitor is charged from and used in conjunction with a primary power supply such as a battery, fuel cell, or generator. It offers a small size as well as the ability to relieve power-intensive systems of peak-power functions. According to the company, this device drastically extends a system's life while reducing its overall cost and size.

The PC2500 is packaged in a durable, lightweight, hermetically sealed aluminum can. It features easily accessible terminals. Its electrostatic storage capability can cycle hundreds of thousands of charges and discharges without performance degradation.

For small orders, the PC2500 ultracapacitor costs $500 per cell. Pricing drops to under $250 per cell for volume orders.

PowerCache Ultracapacitors, 4949 Greencraig Ln., San Diego, CA 92123; (858) 576-7733; fax (858) 503-5221;

Digital Potentiometer Family Features SPI Interfaces Members of the MCP4XXXX family of six single- and dual-channel digital potentiometers are designed for embedded control applications. Each model features an SPI interface.

Both the single- and dual-channel versions are available with resistor values of 10,000, 50,000, and 100,000 Ω. The wiper position for each potentiometer is changed using a standard SPI serial interface. The software shutdown command incorporated in the dual-channel devices lets users open-circuit each resistor individually. This provides the means to reduce current consumption while the device is not in use. The dual-channel devices also feature a shut-down pin.

MCP4XXXX devices boast high accuracy at 8-bit resolution. Single-supply operation ranges from 2.7 to 5.5 V. They also have a low static current of 1 µA maximum. An industrial temperature range of −40°C to 85°C is featured. The digital potentiometers can be used in both the voltage divider and rheostat modes. The dual-channel devices can be connected in series to simplify communication and control.

According to the company, the potentiometers fit a variety of applications, including audio equipment, servomotor control, battery charging and control, power supplies, and LCD contrast control. Packaging options include 8- and 14-pin PDIP, SOIC, and TSSOP.

In 1000-unit quantities, the MCP41XXX single-channel device costs $1.15 each. In similar quantities, the MCP42XXX version costs $1.69 each.

Microchip Technology Inc., 2355 West Chandler Blvd., Chandler, AZ 85224-6199; (480) 786-7200; fax (480) 899-9210;

Capacitors And Assemblies Are Custom Designed For Specific Uses A line of electrolytic capacitors and assemblies feature space-saving, densely packed structures. The devices are developed specifically for engineering projects requiring nonstandard mechanical and electrical specifications.

These devices can be de-signed to incorporate a range of specifications and ratings, including vital cooling requirements. An example of such a custom assembly incorporates a housing mounting screw as one terminal and a topside single screw as the other terminal.

Contact the company for price and availability.

Seacor Inc., 123 Woodland Ave., Westwood, NJ 07675; (201) 666-5600; fax (201) 664-8544;

Electrochemical Supercapacitor Includes A Range Of Voltage Options The BestCap (Battery Energy Saving Technology Capacitor) electrochemical supercapacitor offers a wide variety of voltage options in a single package. Standard voltages of 3.5, 4.5, and 5.5 V are featured. Also, custom voltages range from 1.5 to 10 V. The incorporation of these voltages in the same package eliminates the need for multiple device layouts.

According to the company, this device can store several hundred times the amount of energy stored by conventional aluminum electrolytic capacitors, on a weight and volume basis. It combines high capacitance and low equivalent series resistance (ESR) per unit volume. Capacitance ranges between 50 and 560 mF. ESR values range from 25 to 230 mΩ. Depending on size, maximum leakage current ranges between 5 and 40 µA.

The BestCap can be a power source for portable and battery-backed equipment. It also can be used in hybrid battery packs to reduce peak power on demand and extend battery life. All packaging options use ultra-thin molding wall construction down to 0.7 mm.

In 1000-unit quantities, BestCaps cost between $4.20 and $15, depending on voltage and size specifications.

AVX Corp., P.O. Box 867, Myrtle Beach, SC 29578-0867; (843) 946-0414; fax (843) 448-1943;

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