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HB LED driver powers common-anode LEDs

Posted: 28 Aug 2007 ?? ?Print Version ?Bookmark and Share

Keywords:common-anode LEDs? HB LED driver?


Maxim Integrated Products claims that it has introduced the MAX16821 synchronous high-brightness LED (HB LED) driver with rapid current pulsing, said to be the first to drive common-anode LEDs.

The device's patent-pending, rapid-current-pulsing LED technology meets the demanding requirements of projection applications, making it suitable for front-projection, rear-projection TV (RPTV) and pocket-projector applications that require very fast LED dimming capabilities. The innovative driver architecture of the MAX16821 also allows HB LEDs to be mounted in the common-anode configuration, a necessary requirement for efficient thermal management that reduces system integration and assembly costs.

MAX16821 also features a unique pin configuration capability that allows the device to be operated in either synchronous buck or synchronous boost mode. Synchronous buck and synchronous boost modes allow the LED driver to operate at very high efficiencies, a performance requirement that is important in high-power applications such as automotive exterior lighting and emergency lighting systems.

The wide switching frequency range of 125kHz to 1.5MHz allows small inductors and filter capacitors to be used in applications such as pocket projectors where system designers are faced with extremely tight space constraints. For systems requiring multiple drivers, MAX16821 also features a clock output with 180 phase delay that can control a second, out-of-phase LED driver. This feature can be used to minimize LED current ripple, thereby reducing the size and cost of the input and output filter capacitors even further.

The highly integrated MAX16821 operates from 5.4V to 28V with an LED current-sense voltage of 0.03V, providing the lowest dissipation of power. (Other current-sense voltage versions are also available.) Additional features include programmable hiccup, overvoltage protection, reverse current limit and an output-enable function. MAX16821 operates over the automotive temperature range of -40C to 125C and is available in a tiny, Pb-free, 5mm x 5mm x 0.8mm, 28-pin TQFN package with an exposed pad. Prices start at $1.82 for 1,000-unit pieces.

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