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PDF AAT2825 Data sheet ( Hoja de datos )
| Número de pieza | AAT2825 | |
| Descripción | (AAT2822 - AAT2825) TFT-LCD DC-DC Converter | |
| Fabricantes | Advanced Analogic Technologies | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de AAT2825 (archivo pdf) en la parte inferior de esta página. Total 28 Páginas | ||
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SystemPowerTM
PRODUCT DATASHEET
AAT2822/23/24/25www.DataSheet4U.com
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 (VAVDD) 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
• High Efficiency (93%) @ 50mA Output Current
• 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 (VDD)
• Adjustable Voltage up to 30V @ 20mA
▪ ±3% Typical Accuracy
Negative Output, VGL
• Up to 13.2V Input Supply (VDD)
• 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
2822.2010.02.1.0
www.analogictech.com
1
1 page  
SystemPowerTM
PRODUCT DATASHEET
AAT2822/23/24/25www.DataSheet4U.com
TFT-LCD DC-DC Converter with WLED Driver and VCOM Buffer
Part Number Descriptions
Part Number
AAT2822
AAT2822-1
AAT2823
AAT2823-1
AAT2824
AAT2824-1
AAT2825
AAT2825-1
LCD Bias
9
9
9
9
9
9
9
9
Startup Sequence
VAVDD->VGH->VGL
VAVDD->VGL->VGH
VAVDD->VGH->VGL
VAVDD->VGL->VGH
VAVDD->VGH->VGL
VAVDD->VGL->VGH
VAVDD->VGH->VGL
VAVDD->VGL->VGH
Backlight
9
9
9
9
VCOM Buffer
9
9
9
9
Absolute Maximum Ratings1
TA = 25°C unless otherwise noted.
Description
VIN, EN
VDD, OPIN, OUT, OP+, OP-
LX, WLX
WCOMP, COMP, FB, FBP, FBN, REF, WEN, PWM, WFB, OVP
DRVP
DRVN
Value
-0.3 to 7
-0.3 to 15
-0.3 to 30
-0.3 to VIN+0.3
-0.3 to (VDD+0.3)
-0.3 to (VDD+0.3)
Units
V
Thermal Information2
Symbol
ΘJA
PD
TJ
TLEAD
Description
Thermal Resistance3
Maximum Power Dissipation
Operating Junction Temperature Range
Maximum Soldering Temperature (at Leads)
Value
50
2
-40 to 150
300
Units
OC/W
W
°C
1. Stresses above those listed in Absolute Maximum Ratings may cause permanent damage to the device. Functional operation at conditions other than the operating conditions
specified is not implied. Only one Absolute Maximum Rating should be applied at any one time.
2. Mounted on an FR4 board.
3. Derate 20mW/°C above 25°C.
2822.2010.02.1.0
www.analogictech.com
5
5 Page 
SystemPowerTM
PRODUCT DATASHEET
AAT2822/23/24/25www.DataSheet4U.com
TFT-LCD DC-DC Converter with WLED Driver and VCOM Buffer
Functional Block Diagram
AAT2822
LX
VIN
EN
COMP
VDD
DRVN
FBN
Step-up
Controller
Charge
Pump
Control
FB
DRVP
FBP
OPIN
OP-
OP+
Reference
OP
REF
OUT
WLX
WEN
WDIM
WLED
Control
Brightness
Control
OVP
WCOMP
WFB
AGND PGND1 PGND2
Functional Description
Main Boost Converter
The main boost regulator contains a current-mode,
fixed-frequency PWM architecture to maximize loop
bandwidth and provide fast transient response to pulsed
loads typical of TFT-LCD panel source drivers. The
1.3MHz switching frequency allows the use of low profile,
low value inductors and ceramic capacitors to minimize
the thickness of LCD panel designs.
Dual Charge-Pump Regulator
The AAT2822 provides low-power regulated output volt-
ages from two individual charge pumps to provide the
VGH and VGL supplies. Using a single stage, the VGL
charge pump inverts the supply voltage (VDD) and pro-
vides a regulated negative output voltage. The VGH
charge pump doubles VDD and provides a regulated posi-
tive output voltage. These outputs use external Schottky
diodes and capacitor multiplier stages (dependent upon
the required output voltage) to regulate up to ±30V.
Integrated soft-start circuitry minimizes the start-up
inrush current and eliminates output voltage overshoot
across the full input voltage range and all load condi-
tions. A constant switching frequency of 1.3MHz mini-
mizes output ripple and capacitor size.
White LED Backlight Applications
The AAT2822 consists of a 1.3MHz fixed-frequency DC/
DC boost controller, and an integrated high voltage
MOSFET power switch. A high-voltage rectifier, power
inductor, output capacitor, and sense resistors are
required to implement a DC/DC constant current boost
2822.2010.02.1.0
www.analogictech.com
11
11 Page | ||
| Páginas | Total 28 Páginas | |
| PDF Descargar | [ Datasheet AAT2825.PDF ] | |
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