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White LED drivers offer 90% efficiency

Posted: 20 Jun 2007 ?? ?Print Version ?Bookmark and Share

Keywords:white LED? current-mode boost converters? switching oscillator?


Vishay Intertechnology Inc. releases two new 1.25MHz current-mode boost converters optimized for white LED applications.

The SiP12510 and SiP12511 devices feature an input voltage range of 2.5-6V and output voltages of up to 17V for the SiP12510 and 28V for the SiP12511.

Housed in the SOT23-6 package, the new devices offer a compact LED driver solution requiring minimal external components. Both the SiP12510 and SiP12511 are equipped with an internal integrated power switch and run on a high-frequency 1.25MHz switching oscillator. This allows the use of a small size inductor, reducing the required board space.

This complete LED driver solution integrates several protection features, including overvoltage protection and a cycle-by-cycle current limit of 0.55A supporting up to three parallel strings of 20mA each. A thermal shutdown block provides another layer of protection by shutting down the device once the internal temperature exceeds the 165C typical temperature threshold.

To enable full control over LED illumination intensity, SiP12510 and SiP12511 support both linear and PWM techniques for regulating the LED string current. A built-in three-phase soft-start function diminishes the required peak current during start-up by gradually increasing the switch current limit.

Each device implements a low feedback voltage of 0.1V and a tight switching frequency, resulting in improved conversion efficiency over the full industrial operating temperature range of -40C to 85C.

With their combination of 90 percent efficiency, less than 1?A shutdown current and a small footprint, SiP12510 and SiP12511 are particularly suited for space-constrained, battery-operated, portable applications such as cellphones, PDAs, and digital cameras.

Samples of the new SiP12510 and SiP12511 are available now. Production quantities will be available in Q2 '07, with lead times of 13 weeks for larger orders.

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