Triple Output DC/DC Converter Lights Up Thin-Film Transistor LCDs

Capable of generating both the high voltage and low noise bias voltages required by large thin-film transistor (TFT) LCD panels, the LT1947 triple output dc/dc converter operates from a 2.7V to 6V supply and employs a fixed switching frequency of 3 MHz. The device contains two independent switching regulators, one of which offers an internal 1.1A switch that can generate a voltage as high as 30V, while the second regulatorÕs output is also adjustable up to 30V and can deliver up to 10 mA for positive bias. The negative bias voltage is achieved with a simple level-shift charge pump off the main switch. The 3-MHz switching frequency allows use of tiny, low-profile chip inductors and capacitors, with all components under 1.2-mm in height. Suitable for use in TFT LCDs for notebook, desktop and handheld computers and digital cameras, the low-noise dc/dc converter comes in a 10-lead MSOP package and has a starting price of $2.60 each/1,000.