ADD8754_15 Datasheet, PDF (1/28 Pages) Analog Devices – LCD Panel Power, V, and Gate Modulation

FEATURES
Step-up switching regulator with 2 A power switch
650 kHz or 1.2 MHz switching frequency
Output adjustable to 20 V
350 mA logic voltage regulator
Selectable output voltages: 2.5 V, 2.85 V, 3.3 V
VCOM amplifier with 300 mA drive
Gate pulse modulation circuitry
Independently adjustable delay and falling slope
General
3 V to 5.5 V input
Undervoltage lockout
Thermal shutdown
24-lead, Pb-free LFCSP package
APPLICATIONS
TFT LCD panels for monitors, TVs, and notebooks
GENERAL DESCRIPTION
The ADD8754 is optimized for use in TFT LCD applications,
requiring only external charge pump components to provide all
the requirements for panel power, VCOM, and gate modulation.
Included in a single chip are a high frequency step-up dc-to-dc
switching regulator, logic voltage regulator, VCOM amplifier, and
gate pulse modulation circuitry.
The step-up dc-to-dc converter provides up to 20 V output and
includes a 2 A internal switch. Either a 650 kHz or 1.2 MHz step-
up switching regulator frequency can be chosen, allowing easy
filtering and low noise operation. It achieves 93% efficiency and
features soft start to limit the inrush current at startup.
The internal voltage regulator operates with an input voltage
range of 3 V to 5.5 V and delivers a load current of up to
LCD Panel Power, V_COM,
and Gate Modulation
ADD8754
FUNCTIONAL BLOCK DIAGRAM
COMP SS VIN_1 VIN_2
ADD8754
FB
FREQ
STEP-UP SWITCHING
REGULATOR
LX
SHDN
UNDER VOLTAGE LOCKOUT
AND THERMAL PROTECTION
VDD_2
OUT
LOGIC VOLTAGE
REGULATOR
VCOM AMPLIFIER
LDO_OUT
ADJ
POS
NEG
GATE PULSE
MODULATION
VGH VGH_M VDD_1 CE RE VFLK VDPM
Figure 1.
350 mA. Three selectable output voltages are available: 2.5 V,
2.85 V, and 3.3 V.
The proprietary VCOM amplifier can deliver a peak output
current of 300 mA and is specifically designed to drive TFT
panel loads.
The gate pulse modulator allows shaping of the TFT gate high
voltage to improve image quality. The integrated switches
provide the ability to independently control the delay and slope
for the gate drive voltage.
The ADD8754 is offered in a 24-lead, Pb-free LFCSP package and
is specified over the industrial temperature range of −40 to +85°C.
Rev. 0
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