Features

• Step-Up/Direct-Connect Fractional Charge Pump Provides Up to 92% Efficiency
• Up to 400mA Continuous Output Current
• Independent Current and Dimming Control for
  1-6 LED MAIN, 1-4 LED SUB and RGB LED Displays
• LED Currents Programmable Using 2-Wire I²C™ Serial Interface
• 1% LED Current Matching
• Low Noise Constant Frequency Operation*
• Minimal Component Count
• Automatic Soft-Start Limits Inrush Current
• 16 Exponentially Spaced Dimming States Provides
  128:1 Brightness Range for MAIN and SUB Displays
• Up to 4096 Color Combinations for RGB Display
• Low Operating Current: I_VIN = 180µA
• Tiny, Low Profile 24-Lead (4mm × 4mm × 0.75mm) QFN Package

Typical Application

Description

The LTC3206 is a highly integrated multidisplay LED controller. The part contains a high efficiency, low noise fractional step-up/direct-connect charge pump to provide power for both main and sub white LED displays plus an RGB color LED display. The LTC3206 requires only four small ceramic capacitors plus two resistors to form a complete 3-display LED power supply and current controller.

Maximum currents for the main/sub displays and RGB display are set independently. Current for each LED is controlled with an internal current source. Dimming and ON/OFF control for all displays is achieved via a 2-wire serial interface. Two auxiliary LED pins can be individually assigned to either the MAIN or SUB displays. 16 individual dimming states exist for both the MAIN and SUB displays. Each of the RED, GREEN and BLUE LEDs have 16 dimming states as well, resulting in up to 4096 color combinations.

The LTC3206 charge pump optimizes efficiency based on V_IN and LED forward voltage conditions. The part powers up in direct-connect mode and automatically switches to 1.5x step-up mode once any enabled LED current source begins to enter dropout. Internal circuitry prevents inrush current and excess input noise during start-up and mode switching. The LTC3206 is available in a 24-lead (4mm × 4mm) QFN package.

* U.S. Patent 6,411,531