Components and Power Sources

-- EDN, 12/9/1999

Nickel-electrode MLCCs boost capacitance, lower impedance. A line of multilayer ceramic chip capacitors (MLCCs) uses nickel electrodes to lower cost. The chip capacitors are available in values of 0.1 to 100 µF in Y5V, X5R, and X7R formulations. The company claims that the low-impedance, nickel-based capacitors used in bypass or smoothing circuits outperform tantalum and aluminum-electrolytic units with capacitance values two to 20 times higher. Their advantages over tantalum and aluminum capacitors include lower effective series resistance, lower heat generation, no polarity, and smaller sizes. Prices range from 1 cent to $1.50 (OEM). Taiyo Yuden USA, 1-408-573-4150, ext 16, www.t-yuden.com.

RF LDMOS transistors relocate to plastic packages. Motorola Semiconductor Products lays claim to the first plastic package that can handle as much as 60W lateral-diffused MOS (LDMOS) RF power transistors. The Power RF Plastic (PRFP) packages are available in surface-mount (PRFP-1) or bolt-down (PRFP-2) formats. Both types are compatible with modern automated-assembly lines. The gold-free package assembly integrates IC-like coplanarity with solderable leads, on a copper heat sink. Traditional RF power-transistor packaging uses bipolar transistors in gold-plated ceramic packages, a more costly approach than plastic packaging offers. Motorola SPS, 1-602-244-6920, www.motorola.com/sps.

Smart power switches are virtually kill-proof. The IPS Maxi Series of intelligent power switches incorporates protection against overcurrent, overvoltage, and overtemperature conditions and includes an active inductive-energy clamp. Designed to handle loads as high as 75A, the switches integrate MOSFET with on-resistance as low as 5 m?. The integrated protection features eliminate the need for external components and even account for obscure fault conditions, such as loss of ground or supply. To minimize EMI, the switches feature internal slew-rate control for turn-on and -off and use a low-noise charge pump for the high-side switch. The IPS Maxi Series is available in standard TO-220 and SMD-220 packages, as well as in the company's Super-220 package, which offers thermal and mechanical enhancements to handle currents as high as 75A. Prices range from 55 cents to $3 (100,000). International Rectifier, 1-310-252-7105, www.irf.com.

OCXO touts industry's best stability. The CFPO-11 series of oven-controlled crystal oscillators (OCXOs) is the first true surface-mount oscillator that surpasses Bellcore's Stratum IIIE holdover-stability requirement, according to its maker. The oscillator finds application as a reference-frequency source in Global System for Mobile communications and other cellular base stations, as well as in fixed-line synchronous-digital-hierarchy/synchronous-optical-network switching systems.The CFPO-11 oscillators use high-stability, SC-cut quartz crystals and integrate the bulk of the oscillator circuitry into a single chip. The oscillators consume less than 5W during warm-up and less than 1W in steady-state operation. Prices range from $140 to $280 (1000), depending on specifications. C-MAC Frequency Products, 1-919-941-0430, www.cfpwww.com.

Thermal software targets MCMs. BETAsoft-MCM thermal-analysis software allows you to characterize thermal characteristics of multichip modules (MCMs), BGAs, and other miniature-component packages. The software supports multiple time-varying power sources and substrate layers that use various materials. An extensive materials library comes with the package. Using BETAsoft-MCM enhances the reliability of MCMs by optimizing the thermal design of the MCMs' substrates. You can also avoid thermally induced timing mismatches by maintaining uniform temperatures in MCMs' chips. The software delivers thermal temperature maps with 3-D overviews and offers cut views through all layers of the MCM. BETAsoft-MCM is available on Windows NT, 95, and 98. Prices start at $8000. Dynamic Soft Analysis Inc, 1-412-683-0161, www.nauticom.net/www/beta.

Copper-to-fiber converters are fully redundant. The TX-to-FX redundant converter provides a fully redundant data line that takes over in the event of a failure in the copper or fiber connection. The converter provides redundant connections of both the copper and the fiber interfaces. The interfaces for both media designate a primary and a secondary port. If the link on the primary port fails, control elements in the converter establish a link to the secondary port, which then carries the traffic. Only one of the four ports is active at once, so the product does not interfere with the Spanning Tree Protocol. The converter supports Transition's user-selectable N-way negotiation feature, a utility that teams autonegotiation support with a selectable full- or half-duplex option. The converter is available in stand-alone and chassis-card versions. Unit prices start at $699. Transition Networks, 1-612-996-1559, www.transition.com.

Supersensitive accelerometers break price barrier. The LF Series of single- and three-axis accelerometers breaks the traditional $500/axis price barrier for high-sensitivity accelerometers. Single- and three-axis accelerometers in the LF Series sell for $199 and $419, respectively. The devices are available with full-scale ranges of ±1 and ±2g and spec 125-Hz bandwidth. A noise floor of 100 µg/

allows the accelerometers to resolve extremely small acceleration levels. The accelerometers use a bulk-micromachined silicon sensing element coupled to a signal-conditioning ASIC. The devices operate from a 5V-dc supply or from an 8 to 30V unregulated supply with an optional onboard regulator. The LF Series accelerometers provide an analog-voltage output. Crossbow Technology Inc, 1-408-324-4830, www.xbow.com.

Fan-driver IC needs no other components. The US79 fan-driverICeliminates use of all the drive-circuitry components a traditional cooling fan requires. The three-lead chip reduces component count from eight to one. As a consequence, solder-joint count decreases from 16 to three, thereby increasing reliability. In other reliability enhancements, the IC has no ESD-prone power-supply pin; it instead derives its power through the motor coils. The motor coils provide an ESD filter as well as overvoltage and reverse-voltage protection. ESD tolerance of the US79 is 3000 to 7000V, and that of the complete fan/IC assembly is 15,000 to 25,000V. The IC contains a Hall-effect sensor for motor commutation. It also features overtemperature protection, RFI suppression, output inductive-spike clamping, and locked-rotor protection. The US79 costs 30 cents (OEM). Melexis Inc, 1-603-223-2362, www.melexis.com.

Surface-mount dc/dc converters deliver more than 90% efficiency. The Excalibur Series of 5 to 100W dc/dc convertersfrom Power Trends uses open-frame housings that let you mount the devices vertically or horizontally. You can configure the horizontally mounted converters for either through-hole or solder-reflow surface-mount connections. The first two products in the series are the PT6700, a 13A nonisolated converter, and the PT4480, a 48V-input, 100W-output isolated converter. Using synchronous rectification, the PT6700 provides greater than 90% conversion efficiency. The device accepts inputs of 3.3, 5, or 12V and includes a standby function and a differential remote-sense feature that automatically compensates for any voltage drop from the converter to the load. The PT6700 offers 5-bit-programmable output voltages of 1.3 to 3.5V. The converter costs $19.50 (1000). The 100W PT4480 uses telecomm-standard input voltages of 36 to 75V. The PT4480 also uses a 5-bit programming input to select output voltages of 1.3to 5V. The PT4480 costs $89 (1000). Power Trends, 1-630-393-6901, www.powertrends.com.

Hall sensor is glutton for punishment. The Model 155 noncontacting position sensor integrates a Hall-effect sensor from Melexis Corp (www.melexis.com) and a magnetic circuit to convert radial motion to a voltage-output signal. The device is virtually indestructible and immune to water, dirt, lubricants, shock, and vibration. A bronze sleeve bearing extends the rotational life to 50 million revolutions. Standard off-the-shelf electrical angles are 60, 75, 90, 105, 120, 135, and 150°. Standard linearity is ±2%, with special-order linearity specs as tight as ±0.25%. Model 155 requires an input voltage of 5V±10%; an optional model can operate from 5.5 to 24V-dc supplies. The sensor operates over -40 to +150°C and is EMC-compliant for Class C with conditions 200V/m to 1 GHz. The device costs $18 (OEM). Spectrol Electronics Corp, 1-800-624-8902, www.spectrol.com.