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High-Performance Power ICs and Hall-Effect Sensors
New Software Aids Design with Sanken's STR Series
Free downloadable software provides simple tool for designing switching
power supply designs 
Worcester, MA - Jan. 4, 2006 — Allegro MicroSystems, Inc. continues to expand its power management offerings with free software for customers of our STR-A6100, STR-A6200 and STR-W6700 switching regulator series from Sanken Electric Company, Ltd. Allegro is a wholly owned subsidiary of Sanken Electric, a $1.4 billion company that manufactures semiconductors, discretes, LEDs, and switch-mode power supplies, with headquarters in Saitama, Japan. The two companies jointly develop and market leading-edge products in the areas of power management and motion control.
The STR-CAD Design Aid Software is an easy-to-use design tool that allows the user to develop cost-effective, switching power supply designs using Sanken's powerful STR IC series. STR-CAD allows the user to choose one of several topology options: Pulse-width modulation (PWM), Quasi-Resonant, or Pulse Ratio Control (PRC). Users can select from single or multiple output configurations, and the software then quickly guides the user through the process of specifying power supply requirements with default values, automatically calculating transformer details and other component parameters. It provides a simulated operation of the virtual design created. The user may interactively -- or automatically -- make adjustments in parameters for further investigations.
This software is available for no charge on our website at www.allegromicro.com/pr/strsw.
The Series STR-A6100 are PRC topology ICs (fixed off-time and variable on-time control) designed for a relatively low output power SMPS design of which output power is up to 20 W at universal input or 24 W at 230 VAC input. The auto-standby function reduces input power consumption to less than 50 mW at 230 VAC input by the burst-mode operation, which is stabilized by the auto-bias function to avoid a hiccup phenomenon. Current-mode feedback and leading-edge blanking stabilize the entire power supply operation. Various protections such as overvoltage, overcurrent, overload, thermal shutdown, and an avalanche-guaranteed MOSFET secure good system-level reliability.
The Series STR-A6200 are relatively low-output power off-line PWM topology switching regulator ICs that have a jittering function for cost reduction of EMI noise-filtering circuits. An external adjustment capability provides an optimum jitter-frequency setting. Each device includes various critical and useful functions to realize a simple and reliable design in a switched-mode power supply system, such as primary controlled CV/CC operation, auto-standby, soft-start, protections (overload, overcurrent, overvoltage and thermal), and an avalanche-energy-guaranteed MOSFET.
The Series STR-W67xx includes quasi-resonant topology ICs designed for SMPS power supplies, showing lower EMI noise characteristics - especially at more than 2 MHz - than conventional PWM solutions. They utilize a soft switching to turn on the internal avalanche-guaranteed MOSFET at a close point to ground level (VDS bottom point) through the resonant phenomenon of a primary inductor and resonant capacitor. The package is a fully molded TO-220, which contains the controller chip and MOSFET, and enables the output power up to 140 W at universal input, or 240 W at 230 VAC input.
The bottom-skip function skips the first bottom of VDS and turns on the MOSFET at the second bottom point to minimize increase of operational frequency at light output load, improving system-level efficiency over the entire load condition. Two standby functions reduce the input power at very light output load conditions; one is an auto-burst mode operation internally triggered by sensing on-time, and the other is a manual standby mode that is executed by clamping the secondary output.
Allegro MicroSystems, Inc. is a supplier of advanced mixed-signal power semiconductors and Hall-effect sensors targeted toward the automotive, communications, computer/office automation, consumer and industrial markets. It maintains a leadership position in the integrated magnetic sensor and integrated motor driver product segments. With more than 2,000 employees, Allegro is headquartered in Worcester, MA. Further information about Allegro, as well as free samples on our products, can be found at www.allegromicro.com.
Editorial Contact:
Stephanie A. Fennelly
Director – Marketing Communications
Tel: (508) 854-5363
sfennelly@allegromicro.com