LINEAR dn349f Data Sheet
Summary
This high-integration quad output switching converter is engineered to provide robust, precise power for large TFT LCD panels. Designed with flexibility in mind, it utilizes multiple synchronized switches to power various panel voltages (e.g., logic and bias supplies) over a wide input range (4.5V–8V). This manual details the advanced operation, including soft-start sequencing and panel protection features, offering developers an efficient, compact solution for critical display electronics applications.
Page 1 Text Content
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Quad Output Switching Converter Provides Power for Large TFT LCD Panels – Design Note 349 Dongyan Zhou
Introduction All four regulators are synchronized to a 1.2MHz internal clock, allowing the use of small, low cost inductors and
The LT®1943 is a highly integrated, 4-output regulator
ceramic capacitors. Since different types of panels may
designed to power large TFT LCD panels. The LT1943
require different bias voltages, all output voltages are
employs switching regulators—instead of linear regula-
adjustable for maximum flexibility. Programmable soft-
tors—to minimize power dissipation and accommodate a
start capability is included in all outputs to limit inrush
wide input voltage range. The wide input range, 4.5V to
22V, allows it to accept a variety of power sources, current. The LT1943 has a built-in start-up sequence and panel protection feature. The LT1943 is available in a low-
including the commonly used 5V, 12V and 19V AC adap-
profile 28-pin TSSOP package.
tors. The first buck regulator provides a logic voltage with up to 2A of current. The other three switching regulators
provide the three bias voltages, AVDD, VON and VOFF, , LTC and LT are registered trademarks of Linear Technology Corporation.
required by LCDs.
ZHCS400 4.5V TO 8V B240AVOFF
10V ZHCS400 10V
VIN SW3
SW4 SW2
NFB4 FB2 Si2343DS
RUN-SS
SS-234 AVDD
FB4 CT
PGOOD VON
LT1943
BOOST VON 30V
0.22µFCMDSH-3 E3
SW1 232k
16.5k B230A FB3
VLOGIC
3.3V FB1 GND 10.0k
1.5A SGND
10.0k VC1
VC2 VC3 VC4
L1: TDK RLF7030T-4R7M3R4 L3: TDK RLF5018T-100MR94 DN349 F01 L2: TDK SLF6028T-4R7M1R6
Figure 1. Quad Output TFT LCD Power Supply with 4.5V to 8V Input Voltage Range
Page Summary Contents For LINEAR dn349f Data Sheet
Manual Details
| Brand | Linear |
|---|---|
| Pages | 2 |
| File Size | 82.71 KB |
| Published | June 06, 2026 |
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Frequently Asked Questions
What type of capacitors are recommended for this supply?
The converter uses all ceramic capacitors; X5R or X7R types are recommended.
How does the unit protect itself during a power fault?
If any regulated voltage drops more than 10%, the internal PNP turns off to shut down the panel in a fault condition.
What input voltage range can the regulator accept?
The device supports an adjustable wide input voltage range from 4.5V to 8V.
How is the power-up sequence controlled?
The capacitor at the RUN/SS pin controls the V ramping rate and limits the inrush current during startup.