Power Electronics

Linear LED Drivers Conserve Space in Portable Backlighting Applications

Space-constrained applications, such as handsets, glucometers and other portable devices that require illumination of LCD displays and keypads, now have a linear LED driver option that can save up to 60 percent board space compared to alternate solutions.

The design of Fairchild Semiconductor's FAN5622/24/26 reduces overall component count by eliminating additional passive components used in charge pumps and series boost LED drivers. Fairchild's linear LED drivers simplify design with an easy-to-use control interface and a minimal amount of components. The FAN5622/24/26 are two-, four-, and six-channel current-sink linear LED drivers, ideal for backlighting the main LCD displays or keypads in mobile electronics.

With a very low dropout voltage of 50mV, the FAN5622/24/26 facilitates driving LEDs without an inductor or flyback capacitors. The brightness levels of the LED outputs are programmed through a single-wire control interface. The user can program 32 linear dimming steps and turn on and off the LEDs through this interface by applying digital pulses. This allows for greater dimming resolution using a simple methodology to control this functionality. These LED drivers also have a high peak efficiency (92 percent) thus extending battery life in portable applications.

Additional features include a wide input voltage range (2.7 to 5.5V), short-circuit, under-voltage and thermal protection and less than 1µA shut-down current. The FAN5624, available in micro-MLP packaging (1.4 x 1.8mm), is nearly 60 percent smaller than competing solutions, while the FAN5626, packaged in the 1.6 x 2.1mm MicroPAK(tm) MLP, is nearly 20 percent smaller.

Price (each, 1k pcs.): FAN5622 = $0.47; FAN5624 = $0.55; FAN5626 = $0.63
Availability: Samples available now; Delivery: 6-8 weeks

TAGS: Products
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