Five alive

Linear Technology has released the LTC3208, a fully integrated, 850kHz, low noise, high efficiency 1x/1.5x/2x charge pump multi-display LED driver.


Linear Technology Corporation

announces the LTC3208, a fully integrated, 850kHz, low noise, high efficiency 1x/1.5x/2x charge pump multi-display LED driver.

Linear says it can drive up to 17 LED current sources: a 1-4 LED Main display, 1-2 LED Sub display, a 1-3 LED RGB display, a 1-4 Camera LED display, and a 1-4 LED Auxiliary display, all from a 5mm x 5mm QFN package.

Each display has digital control with independent dimming and programming via a two-wire I2C serial interface. The LTC3208’s input voltage range of 2.9V to 4.5V is optimised for single cell Li-Ion cellular applications.

Efficiencies when driven from a Li-Ion battery (3.6V nominal) reach 95% with quiescent current of only 250uA, maximising battery run-time. The LTC3208 requires only four small capacitors and one resistor to create a tiny, low profile (<34mm2, 0.75mm high) solution capable of powering all LEDs used in five separate displays.

The LTC3208 charge pump automatically optimises efficiency based on VIN and LED forward voltage conditions. The device powers up in 1x mode and automatically switches to boost mode (1.5x) when any enabled LED current source approaches dropout. A subsequent dropout switches the part into 2x mode.

Maximum currents for the Main/Sub/RGB/CAM/Aux displays are set with a single resistor. LED currents are controlled with precision internal current sources while dimming and ON/OFF control for all displays are achieved via a 2-wire I2C serial interface.

256 brightness levels are available for the Main and Sub displays, and 4096 colour combinations are available for the RGB display. Internal circuitry prevents inrush current and excessive input noise during start-up and mode switching.

The LTC3208EUH is available from stock in a 32-lead QFN (5mm x 5mm) package. Pricing starts at $2.55 (€2.05) each for 1,000-piece quantities.