Driver pushes white LEDs where they need to go
By Bill Schweber -- 3/17/2005
White LEDs offer numerous application benefits, but they need controlled current drive for effective operation, and many vendors are offering requisite drivers. The SC606 from Semtech is a charge pump for white or colored LEDs that handles six of these devices. With this IC, designers can program the six LEDs as three pairs, driving each LED pair with 0 to 32 mA in 500 μA-resolution steps. Interface to the controlling processor is via the I2C serial bus.
Overall current accuracy is ±6.5% over the drive range, with typical accuracy of ±2%; drive-matching tolerance is ±3.5% over input voltage and temperature range and 1% at room temperature. The vendor claims efficiency greater than 90%, due to a self-regulating feature that automatically switches conversion modes depending on supply voltage and demand. The 4×4-mm MLP-16 IC operates at 250 kHz or 1.33 MHz and sells for $1.30 (1000).
Semtech Corp, www.semtech.com.
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