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Allegro Continues to Expand Power Management Product
Line
Sanken's ICs offer low cost, high quality, true reliability 
Worcester, MA - March 7, 2005 — Allegro is expanding its power management family with two new product families from Sanken Electric Company, Ltd.: the STR-A61xx series - low standby input power SMPS primary switchers in DIP-8 packages, and the STR-W67xx series - quasi-resonant topology ICs with low EMI noise and bottom skip function. Allegro is a wholly owned subsidiary of Sanken Electric Company, Ltd., a billion dollar 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 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-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.
About Allegro
Allegro MicroSystems, Inc. is a leader in developing, manufacturing and marketing high-performance power and Hall-effect sensor integrated circuits. Allegro's innovative solutions serve high-growth applications within the automotive, communications, computer/office automation, consumer and industrial markets. Allegro is headquartered in Worcester, Massachusetts (USA) with design and applications centers located in North and South America, Asia, and Europe. Further information about Allegro can be found at www.allegromicro.com.
Editorial Contact:
Stephanie Fennelly
Director - Marketing Communications
Tel: (508) 854-5363
sfennelly@allegromicro.com