Buck regulators provide ultra-fast transient response benefits

February 24, 2011 // By Paul Buckley
Semtech has launched the SC171 and SC172 buck regulators, which are 1 A and 2 A output current devices that have been added to the company’s EcoSpeed DC-DC converter platform which includes a broad selection of output current capabilities ranging from 1 A to 30 A. The EcoSpeed converters help designers meet emerging green power requirements by efficiently managing both standby and full current demands in networking and office automation equipment, set-top boxes, portable products, power supply modules and other embedded products, including dynamic point-of-load (POL) applications.

Like all EcoSpeed regulators, the SC171 and SC172 incorporate Semtech’s advanced, patented adaptive on-time (AOT) architecture to achieve what the company claims is best-in-class performance for today’s demanding green power requirements by efficiently managing both standby and full current demands. The AOT architecture uses an advanced control loop that eliminates the need for loop compensation components and enables the use of ceramic input and output capacitors.

Both the SC171 and SC172 are programmable from 200 kHz to 1 MHz, enabling designers to optimize their power supply to maximize either the conversion efficiency or the solution size. They also feature Semtech’s proprietary SmartDrive technology, which is a two-step, high-side FET turn-on technology designed to reduce EMI in noise-sensitive applications.

Additionally, both devices provide high efficiency across the entire load range, with up to 95% peak operating efficiency and selectable, ultrasonic power save (PSAVE), which lowers the switching frequency to cater to light-load requirements during standby. When the load changes from standby to full load, the cycle-by-cycle response of the EcoSpeed architecture quickly exits PSAVE mode to provide very fast wake-up recovery time. This enables power designers to meet “green” regulations, while maintaining fast user performance. To eliminate audible noise during standby, the ultrasonic PSAVE configuration maintains switching frequencies above the 25 kHz audible threshold.

The SC171 and SC172 regulators incorporate soft-start to reduce inrush and minimize stress on the input power source, along with dedicated power-good and enable pins to simplify power supply design. Comprehensive fault protection features include cycle-by-cycle current limit and short circuit, over and under output voltage, and over-temperature protection.

Availability and Pricing

The SC171 and SC172 are available immediately in production quantities. The SC171 is priced at $0.73 each and the SC172 is priced at $0.77 each, both in 3,000-piece lots.

Visit Semtech at www.semtech.com/info