Milpitas, Calif. - Linear Technology's LT1943 quad output regulator is designed specifically to power and protect 22-inch and larger thin-film transistor liquid-crystal display (TFT LCD) panels. Included in the power block (three supplies for the display as well as a 3.3- or 5-V logic supply) is a 2.6-amp boost regulator to drive the TFTs, a high voltage TFT biasing output, an inverter (-10 V) for negative TFT biasing, and a 2.4-amp buck regulator to power VLOGIC. All of the switchers are synchronized to an internal 1.2 MHz clock to minimize switching noise and enable the use of low profile inductors and tiny ceramic input and output capacitors. Its TSSOP-28E exposed pad package and small external components provide a very compact, low profile, thermally efficient footprint.
The LT1943 integrates a host of protection features, including circuitry for protecting the LCD panel by disabling VON if any of the four outputs are more than 10 percent below the normal output voltage. This feature prevents the TFT panel from being exposed to an inrush of VON current that can lead to "flash lighting" and damage. A high-side PNP transistor delays turn-on of the 30-volt VON output until all the other outputs are powered up. The chip's PGOOD output can drive an optional PMOS pass device to provide output disconnect for the AVDD output (12 V). Programmable soft-start is also available for all channels for power sequencing at turn-on.
The LT1943EFE is available from stock. Pricing starts at $4.75 each in 1k pieces.