Features

• 4 Integrated Switches: 2.4A Buck, 2.6A Boost,
• 0.35A Boost, 0.35A Inverter (Guaranteed Minimum Current Limit)
• Fixed Frequency, Low Noise Outputs
• Soft-Start for all Outputs
• Externally Programmable V_ON Delay
• Integrated Schottky Diode for V_ON Output
• PGOOD Pin for AV_DD Output Disconnect
• 4.5V to 22V Input Voltage Range
• PanelProtect^TM Circuitry Disables V_ON Upon Fault
• Available in Thermally Enhanced 28-Lead TSSOP

Typical Application

Description

The LT1943 quad output adjustable switching regulator provides power for large TFT LCD panels. The device, housed in a low profile 28 pin thermally enhanced TSSOP package, can generate a 3.3V or 5V logic supply along with the triple output supply required for the TFT LCD panel. Operating from an input range of 4.5V to 22V, a step-down regulator provides a low voltage output V_LOGIC with up to 2A current. A high-power step-up converter, a lowerpower step-up converter and an inverting converter provide the three independent output voltages AV_DD, V_ON and V_OFF required by the LCD panel. A high-side PNP provides delayed turn-on of the V_ON signal and can handle up to 30mA. Protection circuitry ensures that V_ON is disabled if any of the four outputs are more than 10% below the programmed voltage.

All switchers are synchronized to an internal 1.2MHz clock, allowing the use of low profile inductors and ceramic capacitors throughout. A current mode architecture provides excellent transient response. For best flexibility, all outputs are adjustable. Soft-start is included in all four channels. A PGOOD pin can drive an optional PMOS pass device to provide output disconnect for the AV_DD output.