WLED driver features integrated Schottky diode

Linear Technology has announced the LT3591, a high-efficiency, constant-current white LED driver packaged in a 2-by-3mm DFN package. The device features an integrated Schottky diode on chip, eliminating both the added cost and space required by an external diode. A high-side LED current sense topology enables the LED cathode to be connected directly to ground, creating a single-wire current source.

The LT3591 is designed to drive up to 10 white LEDs from a single Li-ion cell at efficiencies over 78 percent. It switches at 1MHz, allowing the use of a tiny inductor and capacitors while keeping switching noise out of critical RF frequency bands. The combination of the LT3591's high efficiency, low noise and small total solution footprint makes it suitable for handheld applications requiring up to 10 white LEDs for backlighting.

The LT3591 ensures uniform LED brightness by acting as a constant current source, delivering the same current to each white LED, regardless of fluctuations in the LED's forward voltage drop, which varies with temperature, manufacturing tolerances and age. The LT3591 also uses True Color PWM dimming to offer a wide dimming range of up to 80:1. Additional features include output voltage limiting when LEDs are disconnected and ±5 percent reference accuracy.

The LT3591 is available from stock in an 8-lead 2-by-3mm DFN package. Pricing starts at $1.40 each for 1,000-piece quantities.