The LTC3206 charge pump optimizes efficiency based on VIN and LED forward voltage conditions. The device powers up in step-down mode and only switches to step-up mode when any enabled LED current source approaches dropout. Maximum currents for the main/sub/RGB displays are set with a single resistor.
LED currents are controlled with internal current sources while dimming and ON/OFF control for all displays is achieved via a 2-wire I2C serial interface. Sixteen dimming states (logarithmic scale) are available for the main and sub displays, for a 128:1 dimming range. 16 dimming states are available through internal PWM for each of the red, green and blue LEDs, resulting in 4096 color combinations. Internal circuitry prevents inrush current and excessive input noise during start-up and mode switching.
The LTC3206EUF is available from stock in a 24-Lead QFN (4mm x 4mm) package. Pricing starts at $2.20 each for 1,000-piece quantities.
Summary of features: LTC3206
- Up to 92% Efficiency without Inductors
- Step-Up/Step-Down Fractional Charge Pump for Optimal Efficiency
- Independent Current and Dimming Control for 1-6 Main, 1-4 Sub and RGB Displays
- LED Currents Programmed Using a 2-Wire I²C Serial Interface
- <0.7% LED Current Matching Error
- Low Noise, Constant Frequency Operation
- 2.7V to 4.5V Input Voltage Range
- Tiny Solution Footprint, <25mm², <0.75mm Profile
- 4 x 4mm QFN-24 Package