SMPS Primary Regulators feature low EMI noise.
Press Release Summary:
With low EMI noise characteristics at more than 2 MHz, STR-W67xx series of low-power off-line SMPS primary regulators includes quasi-resonant topology ICs, and enables output powers up to 160 W at 120 Vac, or 240 W at 230 Vac input. Soft switching mechanism turns on internal MOSFET at close point to VDS bottom point, while bottom-skip function skips first bottom of VDS and turns on MOSFET at second bottom point to minimize increase of operational frequency at light output load.
Original Press Release:
Allegro Introduces New Family of Low-Power Off-Line SMPS Primary Regulators
With Low EMI Noise and Bottom Skip Functionality
Worcester, MA, August 11, 2006 - Allegro announces a new line of low-power off-line SMPS primary regulators targeted at the consumer electronic, industrial appliance and home appliance markets. Allegro's STR-W67xx series includes quasi-resonant topology ICs designed for SMPS power supplies, showing lower EMI noise characteristics, especially at more than 2 MHz, higher than conventional PWM solutions. They utilize a soft switching mechanism to turn on the internal MOSFET at a close point to ground level (VDS bottom point) through the resonant phenomenon of a primary inductor and resonant capacitor.
The bottom-skip function skips the first bottom of VDS and turns on the MOSFET at the
second bottom point to minimize the 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.
In general applications, the manual standby mode reduces the input power most as compared to the auto-burst mode. The soft-start function minimizes surge voltage and
reduces power stress to secondary rectifying diodes during startup sequence. Various protections, such as overvoltage, overload, overcurrent, maximum ontime protection and avalanche-guaranteed MOSFET, secure good system-level reliability.
The package is a fully molded TO-220, which contains the controller chip and MOSFET, and enables output powers up to 160 W at 120 VAC input, or 240 W at 230 Vac input. Pricing in 1K quantities is detailed below:
o STR-W6735: $1.56
o STR-W6753: $1.33
o STR-W6754: $1.67
o STR-W6756: $1.85
o STR-W6765: $1.72
About Allegro
Allegro MicroSystems, Inc. is a global leader in the development, manufacture and marketing of high-performance power integrated circuits and integrated Hall-effect magnetic sensors. Allegro's innovative, system-level solutions serve high-growth applications within the automotive, computer/office automation, industrial, consumer and communications markets, while our leading-edge product and processes reinforce our expertise in motor driver and power management technology. In addition, we also hold leading positions within printer, scanner, copier and portable device (e.g. cellular phones) applications. With more than 2,400 employees, Allegro is headquartered in Worcester, MA. Further information about Allegro can be found at www.allegromicro.com.
