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Siliconix announces replacements for UCC380x, UCC280x controllers

Posted: 10 Nov 2004 ?? ?Print Version ?Bookmark and Share

A new family of low-power current-mode controllers that provide increased efficiency and flexibility in cost-sensitive power-supply designs was announced by Siliconix Inc., a subsidiary of Vishay Intertechnology Inc.

Touted to be the first true direct replacements for the industry-standard UCC380x and UCC280x families of low-power current-mode controllers, the new SiP280x pulse-width modulation (PWM) controllers serve as versatile, low-cost building blocks for a broad variety of converters in both offline and dc-to-dc current-mode switching power supplies in industrial, fixed telecom and datacom applications. These products also are suitable for point-of-load (POL) regulation, high-efficiency dc-to-dc converter modules, and buck, boost, flyback and forward converters.

Siliconix's pin-for-pin-compatible replacements to the UCC380x/UCC280x family include the SiP2800, SiP2801, SiP2802, SiP2803, SiP2804 and SiP2805, each of which is built on a BiCMOS process and is available in either an SO-8 or TSSOP-8 package. Intended for 10W to 250W power supplies, the controllers can operate from a supply voltage as low as 5V.

In addition, the SiP280x series provides improved power supply efficiency relative to the UC384x/UC284x devices by taking advantage of Siliconix's advanced BiCMOS design and processing. According to the press release, this yields significantly lower start-up and operating current requirements of 100?A and 500?A, respectively. The low start-up current substantially reduces dissipation in any dropping resistors required for start-up of the part, while the minimized operating current drastically cuts the amount of power that must be supplied to a SiP280x controller merely to power the IC, the company added. The lower start-up and operating currents additionally allow the SiP280x devices to use smaller external capacitors from the VCC pin to ground.

Other features

With an internal soft-start mechanism that is active at power-on and under fault conditions, the SiP280X controllers reduce stress on external components, enhancing power supply performance and reliability. Siliconix said the new ICs also feature built-in leading-edge blanking on the current sense pin. This blanking eliminates the need for external filter components while keeping voltage spikes from triggering the parts' current comparators, ensuring that the current-regulation loop and the overcurrent limiter circuits function properly.

Rated for operation between the -40C to 85C temperature range, members of the SiP280x series also feature a variety of turn-on and turn-off thresholds to accommodate various supply voltage, UVLO and hysteresis requirements.

Samples and production quantities of the SiP280x controllers are already available, with lead times of 8 to 12 weeks for larger orders. Pricing for U.S. delivery is $1.50 for quantities of 1,000 pieces or more.

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