Demonstration circuit 629 is a multi-display LED controller featuring the LTC3205. The LTC3205 is a highly integrated multi-display LED controller. This device contains a high efficiency, low noise fractional step-up/step-down charge pump to provide power for a main and sub white LED display, plus an RGB color LED display. The LTC3205 requires only four small ceramic capacitors plus two resistors to form a complete 3-panel LED power supply and a current controller. Maximum currents for the main/sub and RGB displays are set independently with a single resistor. Current for each LED is controlled with an internal current source. Dimming and ON/OFF control for all displays is achieved via a 3-wire serial interface. Four dimming states exist for the main and sub panel displays and 16 dimming states are available via internal PWM for the red, green, and blue LEDs resulting in up to 4096 color combinations. The LTC3205 charge pump optimizes efficiency based on VIN and LED forward voltage conditions. The part powers up in step-down mode and automatically switches to step-up mode once the first LED current source begins to enter dropout. Internal circuitry prevents inrush current and excess input noise during startup and mode switching.