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 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
Thermally Enhanced 28-Lead TSSOPApplication Large TFT-LCD Desktop Monitor Displays
Flat Panel TelevisionsPinout
SpecificationsVIN Voltage .............................................................. 25V
BOOST Voltage ........................................................ 36V
BOOST Voltage Above SW1 ..................................... 25V
BIAS Pin Voltage ..................................................... 18V
SW2, SW4 Pin Voltages .......................................... 40V
SW3 Voltage ............................................................ 36V
FB1, FB2, FB3, FB4 Voltages ...................................... 4V
NFB4 Voltage ............................................... +6V, 0.6V
VC1, VC2, VC3, VC4 Pin Voltages .............................. 6V
RUN-SS, SS-234 Pin Voltages ................................... 6V
PGOOD Pin Voltage ................................................. 36V
E3 Pin Voltage ......................................................... 36V
VON Voltage ............................................................. 36V
CT Pin Voltage ........................................................... 6V
Junction Temperature ........................................ 125°C
Operating Temperature Range (Note 2)40°C to 85°C
Storage Temperature Range ..............65°C to 150°C
Lead Temperature (Soldering, 10 sec)................. 300°C
Description
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 lowerpower step-up converter and an inverting converter provide 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 VON is disabled if any of the four outputs are more than 10% below normal voltage.
All LT1943 switchers are synchronized to the 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 AVDD output.
LT1943 Data Sheet
