August 24, 2005, Milpitas, CA--Linear Technology today announce the LT3486, a dual step-up DC/DC converter specifically designed to drive up to 16 white LEDs (8 LEDs in series per channel) with constant current. In addition true pulse width modulation (PWM) dimming delivers constant current to the LEDs, keeping the emitted light at a constant color.
Dimming is controlled with the duty cycle of the PWM driver. This method allows for a wide 1000:1 dimming range. The LT3486's high efficiency, current mode and fixed frequency operation ensures uniform LED brightness, low noise and maximum battery life.
Two independent converters are capable of driving asymmetric LED strings (up to 8 in a series per converter) from an input voltage of 2.5 V to 24 V, delivering efficiencies up to 85%. A 5-mm x 3-mm DFN package and tiny externals provide a very compact footprint for space-constrained handheld applications. The 2.5-V to 24-V input voltage range enables it to operate in applications from Li-Ion powered handheld devices to automotive backlighting applications.
The LT3486 switching frequency can be set between 200 kHz and 2 MHz via a single resistor, enabling the designer to minimize solution footprint and maximize efficiency. Because the LT3486 utilizes constant frequency architecture, noise is minimized, eliminating potential interference with any onboard RF or audio circuitry.
Additional features include internal soft-start/inrush current limiting, and open LED protection. The combination of the LT3486's high efficiency, versatility, low noise, and extremely small "total solution" footprint make it ideal for a variety of backlighting applications requiring many white LEDs in a space constrained form factor.