LT1942 - Quad DC/DC Converter for Triple Output TFT Supply Plus LED Driver

Features

• Click Here For LT1942 Evaluation Kit
• Triple Output TFT Supply with Built-In Power Sequencing
• Integrated White LED Backlight Driver
• Integrated Schottky Diodes
• Active Ballast Circuitry Ensures Precise Current Matching in White LEDs
• Low Noise 1MHz Fixed Frequency Operation
• 2.6V to 16V Input Voltage Range
• Soft-Start Limits Inrush Current
• TFT Supply Output Voltages Independently Set (Not Charge Pump Derived)
• Power Good and Output Disconnect for TFT Supply
• Built-In LED Dimming Capability
• Open LED Protection for LED Driver
• 24-Lead QFN Package (4mm × 4mm)

Typical Application

Description

The LT1942 is a highly integrated quad switching regulator designed to provide all necessary power supply functions for TFT displays, including the white LED backlight driver. The TFT supply incorporates two boost and one inverting DC/DC converters. The TFT supply output voltages are independently set, unlike charge pump solutions which have many limitations. Power sequencing for the TFT supply is built into the part and is user programmable.

The LED driver is a boost DC/DC converter that can be independently controlled. The LED driver has built-in dimming control for precise control of LED current. An 8:1 dimming range is achieved by adjusting the CTRL4 voltage.The user can elect to drive a single string or two strings of LEDs. An LED ballast circuit is included to precisely match the LED currents if two strings of LEDs are used. Soft-start is built into the LED driver as well as the primary TFT supply.

The LT1942 is available in a low profile (0.75mm) 24-lead QFN (4mm × 4mm) package.

Packaging

QFN-24

Order Info

• Part numbers ending in PBF are lead free. Please contact LTC marketing for information on lead based finish parts.
• Part numbers containing TR or TRM are shipped in tape and reel or 500 unit mini tape and reel, respectively
• Please refer to our general ordering information or the product datasheet for more details

Package Variations and Pricing

Part Number	Package	Pins	Temp	Price (1-99)	Price (1k)*	RoHS Data
LT1942EUF	QFN	24	E	$3.27	$2.75	View
LT1942EUF#PBF	QFN	24	E	$3.27	$2.75	View
LT1942EUF#TR	QFN	24	E		$2.85	View
LT1942EUF#TRPBF	QFN	24	E		$2.85	View
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^* The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Linear Technology sales office or authorized distributor.

Evaluation Kits

Part Number	Description	Price
DC688A	LT1942EUF | Quad Converter For TFT Supply and LED Driver, Vin=3V-4.5V, Von=10V/2mA, Voff=-10V/2mA, AVdd=5V/40mA	$100.00
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Applications

• Poly-Silicon TFT Displays
• Amorphous Silicon TFT Displays

Simulate

To simulate selected Linear Technology products, please download LTSpice / SwitcherCAD III. This powerful schematic capture and simulation tool includes macro models for 80% of Linear Technology's switching regulators, over 200 op amp models, as well as resistors, transistors and MOSFET models.

For other simulation tools, visit our Design Simulation and Device Models page.