Power Electronics

Data Points

Chip Combines PWM and Hot-Swap Controllers

Maxim Integrated Products' new MAX5042 is a 2-switch clamped PWM converter with integrated hot-swap controller. It simplifies the design of isolated dc-dc converters that are meant to be hot-plugged into a live backplane. It eases the dc-dc converter design further by integrating high-side and low-side power MOSFETs.

The 2-switch topology lowers the voltage stress on the power MOSFETs when compared to the ground-referenced single-switch topology, and eliminates the transformer reset winding. Operating over a 20-V to 76-V input range, it generates low-voltage outputs while switching at frequencies up to and above 500 kHz. Outputs up to 50 W are possible with efficiencies greater than 90%. The chip also implements both flyback and forward converters with voltage-mode or current-mode operation.

Other features include a look-ahead PWM signal to allow secondary-side synchronous rectification and a high-voltage startup regulator. A related product, the MAX5043, is offered without the hot-swap controller. Both ICs come in 56-pin QFNs with prices starting at $5.25 for the MAX5042 and $4.67 for MAX5043 in lots of 1000.

For more information, visit www.maxim-ic.com.

Ultracapacitors May Replace Batteries

The Powercache energy-storage module from San Diego-based Maxwell Technologies combines a bank of 22 ultracapacitors with dc-dc boost converter and cell-balancing circuitry to provide short-term energy storage for telecom applications. The module is intended to replace 48-V lead-acid batteries in applications that can benefit from the higher reliability of the ultracapacitors.

These components provide bursts of power during disturbances lasting several seconds. That duration is sufficient for ride-through to a generator, microturbine or other long-term power source. Powercache also recharges in minutes and supports in excess of 100,000 cycles independent of the depth of discharge.

Two standard versions of the Powercache are offered with ratings of 1.6 kWminutes or 2.3 kWminutes. The module measures 17 in. × 7 in. × 23 in. and is available in a 19-in. or 23-in. rack-mount configuration.

For more information visit www.maxwell.com.

PWM Controller Targets Battery-Powered Designs

Camarillo, Calif.-based Semtech's SC1404 is a multi-output voltage PWM controller for battery-powered applications. Its features simplify designs, reduce parts count and lower system costs, while the controller achieves more than 95% power conversion efficiency. Integrating two synchronous PWM controllers, preset to generate independent 3.3-V and 5-V supplies, it also supplies a 12-V, 200-mA linear regulated output. Input voltage range is 6 V to 30 V.

The SC1404's PWM controllers switch out-of-phase to provide ripple cancellation at the input, reducing input capacitance needs by as much as one-half compared to in-phase solutions. The chip also lowers the required output capacitance by allowing designers to externally compensate the control loop.

Semtech's Virtual Current Sense provides peak current-mode control based on an internally generated current sense signal that is an order of magnitude larger than that generated by conventional current sensing schemes.

The SC1404 is priced in 1000-pc quantities at $4.05 for the TSSOP-28 package and $3.95 for the SSOP-28 package.

For more information on Semtech's SC1404 PWM controller, visit www.semtech.com.

Driver/Controller IC Eliminates EMC Filters

Austrian semiconductor supplier austriamicrosystems recently unveiled a fully programmable IC specifically designed for high-current electric-motor applications. The AS8444 PWM dc motor driver/controller is designed for electric motors from 200 W to 700 W, with low RF emissions over its entire frequency range. Because the AS8444 features an integrated EMC-compliant driver, it eliminates the need for external EMC filter components.

The AS8444 IC enables designers to adapt their electronic subsystems for operating efficiency and manufacturing efficiency. The low RF emission and EMC compliance is attributed to a patented dynamically self-adjusting slew rate regulated switching technology. The field programmability of this parameter makes it easier to achieve EMC compliance at the system level without adding external components.

Designed to interface with a simple microprocessor and a high-side N-channel power FET, the AS8444 can be programmed for dc motor current, voltage or speed regulation, with fast overcurrent detection and protection, over/undervoltage detection and protection, battery voltage monitoring, and both external and on-chip temperature detection functions. The AS8444/46 comes in a 28-pin SOIC package and is priced at $2.00 in high volumes.

For more information, visit www.austriamicrosystems.com.

Power Supplies Double Rated Output

Two power supplies series from San Diego-based Lambda deliver 200% of the nominal current rating for up to 10 sec, useful when powering applications such as motors and printers. The ZWS150PAF and ZWS240PAF Series produce outputs of 150 W and 240 W, respectively, while operating from universal inputs of 85 Vac to 265 Vac. These supplies offer 24-V, 36-V or 48-V output and feature active power factor correction (PFC) to meet EN61000-3-2.

When convection cooled, the ZWS150PAF produces its full 150-W continuous output at ambients up to 50∞C. That rating increases to 200 W when the application uses forced air cooling of 1.5 m/sec. Similarly, the 240-W model delivers 300 W with forced air cooling. Prices start at $120 in single-unit quantities.

For more information on the ZWS150PAF and ZWS240PAF Series, visit www.lambdapower.com.

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