Product category:
Power Supply ICs and Controllers
News Release from: Allegro MicroSystems Europe | Subject: STR-W67xx Series
Edited by the Electronicstalk Editorial
Team on 18 April 2005
Quasiresonant topology cuts switching
noise
A new family of switch-mode power-management ICs features a quasiresonant topology which exhibits lower EMI noise characteristics than designs based on conventional PWM switching.
The STR-W67xx Series from Allegro MicroSystems Europe is a family of switch-mode power-management integrated circuits featuring a quasiresonant topology which exhibits lower EMI noise characteristics - especially at more than 2MHz - than designs based on conventional PWM (pulsewidth-modulation) switching A fully moulded TO-220 package contains the controller chip and MOSFET
This article was originally published on Electronicstalk on 30 Aug 2000 at 8.00am (UK)
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Output power is up to 140W at universal input or 240W at 230V AC input.
The new devices use a soft switching technique to turn on the internal avalanche-guaranteed MOSFET at a point near ground level through a resonant circuit consisting of a primary inductor and a resonant capacitor.
A "bottom skip" function minimises the increase of operational frequency at light output loads, improving system-level efficiency over the entire load range.
Two standby functions reduce the input power at very light output load conditions: one is an auto-burst mode operation internally triggered by sensing the "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 provides a greater reduction in the input power than the auto-burst mode.
The soft-start function minimises surge voltage and reduces power stress to secondary rectifying diodes during the startup sequence.
Built-in protection includes overvoltage, overload, overcurrent, maximum on-time protection and an avalanche-guaranteed MOSFET, ensuring good system-level reliability.
Applications include switch-mode power supplies for consumer electronics products, PCs, industrial equipment and domestic electrical appliances.
The range consists of three devices: STR-W6753 - 650V/1.7ohm, 58W (universal input)/120W (230V input); STR-W6754 - 650V/0.98ohm, 100/160W; and STR-W6756 - 650V/0.73ohm, 140/240W.
Sanken Electric semiconductor devices are available in Europe from Allegro MicroSystems Europe, a Sanken Electric subsidiary company, and via its network of distributors.
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