High Current Quad Output
Regulator for TFT LCD Panels
■ 4 Integrated Switches: 2.4A Buck, 2.6A Boost,
0.35A Boost, 0.35A Inverter (Guaranteed Minimum
■ Fixed Frequency, Low Noise Outputs
■ Soft-Start for all Outputs
■ Externally Programmable VON Delay
■ Integrated Schottky Diode for VON Output
■ PGOOD Pin for AVDD Output Disconnect
■ 4.5V to 22V Input Voltage Range
■ PanelProtectTM Circuitry Disables VON Upon Fault
■ Available in Thermally Enhanced 28-Lead TSSOP
■ Large TFT-LCD Desktop Monitors
■ Flat Panel Televisions
, LTC and LT are registered trademarks of Linear Technology Corporation.
PanelProtect is a trademark of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
The LT®1943 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 VLOGIC with up to
2A current. A high-power step-up converter, a lower-
power step-up converter and an inverting converter pro-
vide the three independent output voltages AVDD, VON and
VOFF required by the LCD panel. A high-side PNP provides
delayed turn-on of the VON signal and can handle up to
30mA. Protection circuitry ensures that VON is disabled if
any of the four outputs are more than 10% below the
All switchers are synchronized to an internal 1.2MHz
clock, allowing the use of low profile inductors and ce-
ramic 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 AVDD output.
VIN, 8V TO 20V
VIN SW3 SW2
Quad Output TFT-LCD Power Supply