DATA SHEET
AAT2822/2823/2824/2825
TFT-LCD DC/DC Converter with WLED Driver and VCOM Buffer
General Description
The AAT2822-AAT2825 family of integrated panel power
solutions provides the regulated voltages required by an
active-matrix thin-film transistor (TFT) liquid-crystal dis-
play (LCD). The AAT2822 includes a triple-output DC-DC
converter, a LED backlight driver, and a VCOM buffer in
a 4 mm x 4mm TQFN package. The primary 1.3MHz
DC-DC boost converter uses an ultra-small inductor and
ceramic capacitor to generate output voltage (V
AVDD
) of
up to 14.5V for the charge pumps. The low on-resistance
of the integrated power MOSFET allows for efficiency up
to 93%.
The two charge pumps independently regulate a positive
output (VGH) and a negative output (VGL). These low-
power outputs use external diode and capacitor stages
to regulate output voltages up to +30V and down to
-30V. A proprietary regulation algorithm minimizes out-
put ripple when using small capacitors.
The high efficiency backlight driver provides a constant
current output capable of boosting up to 28V. The driver
is an ideal power solution for backlight applications with
up to seven white LEDs in series or up to 39 white LEDs
in a parallel and series configuration. LED brightness is
PWM controlled up to 1kHz. Filtered PWM is supported
for higher frequencies.
The high slew rate operational amplifier is suitable for
VCOM buffering and gain adjustment.
The sequencing of the power supplies ensures proper
panel startup and avoid damage to the device.
The AAT2822 family is available in a Pb-free, 24-pin 4 x
4mm TQFN package and operates over the -40°C to
+85°C temperature range.
Features
LCD Bias Power
•
2.5V to 5.5V Input Supply Range
•
1.3MHz Fixed Frequency Current-Mode Step-Up
Regulator
•
Fast Transient Response
•
Adjustable Voltage up to 14.5V
▪
±1% Typical Accuracy
•
Small External Inductor and Capacitors
•
Integrated Soft Start and Sequencing of All Rails
•
Short-Circuit, Over-Voltage, and Over-Temperature
Protection
Positive Output, VGH
•
Up to 13.2V Input Supply (V
DD
)
•
Adjustable Voltage up to 30V @ 20mA
▪
±3% Typical Accuracy
Negative Output, VGL
•
Up to 13.2V Input Supply (V
DD
)
•
Adjustable Voltage down to -30V @ 20mA
▪
± 3% Typical Accuracy
WLED Driver
•
Input Voltage Range: 2.5V to 25V
•
Maximum Continuous Output:
▪
12V @ 260mA
▪
28V @ 50mA
•
Panel sizes from 5" – 10"
▪
5.0" 3S5P
▪
5.6" 3S6P
▪
7.0" 3S9P
▪
8.0" 3S10P/11P
▪
10" 3S13P
•
Constant LED Current with 6% Accuracy
•
PWM Dimming Control
▪
Up to 1kHz
•
1.3MHz Switching Fixed Frequency
▪
Up to 90% Efficiency
VCOM Buffer
•
High-Performance
▪
13V/µs Slew Rate
▪
12MHz, -3dB Bandwidth
•
±75mA Output Short-Circuit Current
•
Low 1.5mA Quiescent Current
Applications
•
•
•
•
Automotive Displays
Digital Photo Frames
Netbooks
PNDs
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202081B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 2, 2012
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