Linear Technology has announced the LTC3206, an 800kHz, step-up/step-down fractional charge pump voltage converter.

In total, it can drive a one to six LED main display, a one to four LED sub-display plus an RGB display, all from a 4x4mm QFN package.

Each display has digital control with independent dimming and programming via a two-wire I²C interface.

Input range is 2.8 to 4.5V, making it suitable for single cell Li-ion use.

Maximum efficiency is 92 per cent, although as with all charge pumps this varies considerably as input voltage changes. Quiescent current is 180uA.

Four capacitors and two resistors are required, giving a minimum total footprint under 25mm², by 0.75mm high.

The device responds to both Vin and LED forward voltage conditions, powering up in step-down mode and only switching 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.

Sixteen log-spaced dimming states are available for the main and sub displays giving a 128:1 dimming range, or 4096 colours with red, green and blue LED through internal PWMs. Internal circuitry controls in-rush current and input noise during start-up and mode switching.

Available from stock in a 24-Lead QFN (4x4mm) package.

www.linear.com