Allegro introduces a new three-channel constant current LED driver with an on-chip oscillator for programmable brightness control. A typical application is to drive a set of red/green/blue LEDs for one pixel in a large display or photographic equipment. The 10-bit pulse width modulation per channel allows precise control of the brightness of the LEDs, with 7-bit analog current control compensation per channel to adjust color balance. Allegro's 6271A drives up to 150 mA per channel and operates up to 17V. Can be applied to large video displays, signage and architectural and decorative lighting.
A maximum operating voltage of 17V can be connected in series with up to 4 or more LED strings at each output. An on-chip voltage regulator provides internal logic and reduces the number of external components and connections. The control data is serially downloaded, thus minimizing the number of pins and package size of the device. Only four control signals are required: clock, serial data, latch and output enable signals. These signals are buffered into on-chip to drive the next pixel in the concatenation cascade. A novel clock regeneration architecture allows for a large number (hundreds, depending on clock frequency and pixel space) of devices connected in series. The pixel space can range up to 3m (10 feet).
The A6281 requires only three external components to configure: a resistor to set the maximum output current, the on-chip regulator's decoupling capacitor, and the LED operating voltage. High integration and a tiny 3 x 3mm QFN package make the board design even more compact. Allegro's A6281 has a temperature range that extends from -40°C to +85°C.
Introduction to Allegro
Allegro MicroSystems continues to lead the world in the development, manufacturing and marketing of high-performance power ICs and integrated Hall-effect magnetic sensors. Allegro's innovative system-level solutions serve high-growth applications in the automotive, computer/office automation, industrial, consumer, and communications markets. With more than 2,500 employees, Allegro is headquartered in Worcester, Massachusetts. Flores lighting: the first light of home lighting (Figure)
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