High-current convertors drive OLED displays

Edited by the Electronicstalk editorial team Mar 15, 2007

Low-noise boost convertors integrate power switches, Schottky diodes and output disconnect circuitry.

The LT3494/A from Linear Technology is a low-noise boost convertor with integrated power switch, Schottky diode and output disconnect circuitry.

The LT3494 uses a 180mA switch, whereas the LT3494A uses a 350mA switch, and both parts are packaged in 3 x 2mm DFN-8 packages.

Their wide 2.3 to 16V input voltage range enables operation from single cell Li-ion batteries up to fixed 12V input rails, delivering outputs up to 40V.

The LT3494 can deliver over 17mA of current at 15V from a single Li-ion cell, making it ideal for applications such as OLED displays.

The LT3494A has higher current capability and can deliver over 27mA of current at 15V from a single Li-ion cell.

Both parts use a unique control technique that delivers both high efficiency and low output ripple over a wide load current range.

This technique guarantees that the switching frequency stays above the audio band for the entire load range, making it ideal for noise-sensitive applications such as MP3 players.

The combination of the LT3494/A's 3 x 2mm DFN package and tiny, low cost ceramic capacitors and inductors provides a very compact solution footprint.

The LT3494's NPN switch achieves a collector-emitter saturation voltage of only 110mV at 100mA, offering efficiencies as high as 80%.

Only 65uA of quiescent current (less than 1uA in shutdown) maximises battery run-time, and integrated Schottky diodes and output disconnect circuitry eliminates costly external circuitry.

Finally, an integrated dimming/contrast adjustment function is included for display applications.

The LT3494EDDB and LT3494AEDDB are both available from stock in 8-lead 3 x 2mm DFN packages.

Pricing starts at US $1.45 each for 1000-piece quantities.