Charge Pump Powers Cell Phone Displays

Called an I2C Multidisplay LED Controller, the LTC3206 is a charge-pump voltage converter for powering LEDs and other displays in cell phones. It can drive a 1- to 6-LED main display, a 1- to 4-LED sub-display and an RGB display, all from a single device in a 4 mm x 4 mm, 24-lead QFN package. Each display has digital control with independent dimming and programming via a 2-wire I2C serial interface. Sixteen dimming states (logarithmic scale) are available for the main and sub-displays and also for the RGB display, which results in 4,096 possible color combinations. The device runs from an input voltage range of 2.8V to 4.5V, which optimizes it for single cell Li-Ion applications. A complete power supply consists of the LTC3206, four small capacitors and two resistors that occupy an area of less than 25 mm² and 0.75 mm high. Quiescent current draw is 180 µA, extending battery run-time. Pricing starts at $2.20 each/1,000. LINEAR TECHNOLOGY CORP., Milpitas, CA. (408) 432-1900.