AAT2847_08 Datasheet, PDF (1/20 Pages) Advanced Analogic Technologies – Four-Channel Backlight Driver with Dual LDOs

ChargePump^TM
PRODUCT DATASHEET
AAT2847
Four-Channel Backlight Driver with Dual LDOs
General Description
The AAT2847 is a highly integrated power solution for
single cell Li-Ion/Polymer based liquid crystal display
(LCD) display applications. It includes a four channel
light emitting diode (LED) backlight driver and two inte-
grated 200mA low dropout voltage regulators (LDOs) as
additional power supplies for display and camera related
chipsets.
The backlight driver in the AAT2847 is a low noise tri-
mode DC/DC charge pump converter. Each of the four
channels of the backlight driver is capable of delivering
up to 20mA of bias currents for white LEDs. The white
LED (WLED) backlight bias current matching is 1% which
helps provide uniform display brightness.
AnalogicTech’s AS²Cwire™ (Advanced Simple Serial
Control™) serial digital interface is used to enable, dis-
able, and set the current for each backlight LED channel.
Each LED channel has sixteen available current level set-
tings in three separate current scales, plus four available
current level settings on a low level current scale.
Each LED channel is equipped with built-in short circuit
protection and auto disable functionality. A low shutdown
current feature disconnects the load from the input and
reduces quiescent current to less than 1µA.
The AAT2847 is available in the thermally enhanced
20-pin 3x4x0.75mm TQFN package.
Typical Application
Features
• Input Supply Voltage Range: 2.7V to 5.5V
• Tri-Mode (1X/1.5X/2X) Charge Pump:
▪ Delivers up to 120mA of Output Current
• Integrated LCD Display Solution:
▪ Four-Channel WLED Backlight
• User-Programmable WLED Current Scales: 30mA,
20mA and 15mA.
▪ Sixteen Programmable Current Level Settings
• User Selectable Low Level Current Scale
▪ Four Programmable Current Level Settings
▪ ^{Dual 200mA LDOs (w/Separate Enables)}
• Single-Wire AS²Cwire Serial Interface for Configuration/
Control
▪ Four Addressable Registers
▪ Fast, 1MHz Serial Interface
• > 90% Peak Efficiency
• LDO Output Voltages:
▪ AAT2847-EE: User-Programmable
▪ AAT2847-QG: 2.8V and 1.5V
▪ AAT2847-QI: 2.8V and 1.8V
• Over-Temperature Protection
• Available in 3x4x0.75mm TQFN34-20 Package
• -40°C to +85°C Temperature Range
Applications
• Camera Function Power Supplies
• Camera Phone Displays
• LCD Modules
• White LED Backlighting
VBAT
3.6V
CIN
2.2µF
AS²Cwire
Backlight Control
LDO A Enable
LDO B Enable
C1
C2
1µF
1µF
C1- C1+ C2- C2+
OUT
IN
AAT 2847-EE
D1
D2
D3
D4
IN
LDOA
EN/SET
ENA
ENB
GND
FBA
LDOB
FBB
PGND
COUT
1µF
WLEDs
OSRAM LW M673
or equivalent
200mA
CLDOA
2.2µF
200mA
CLDOB
2.2µF
VBAT
3.6V
CIN
2.2µF
AS²Cwire
Backlight control
LDO A Enable
LDO B Enable
C1
C2
1µF
1µF
C1- C1+ C2- C2+
OUT
IN
AAT 2847-QI
D1
D2
D3
D4
IN
LDOA
EN/SET
ENA
ENB
LDOB
GND
PGND
COUT
1µF
WLEDs
OSRAM LW M673
or equivalent
CLDOA
2.2µF
VOUTA
2.8V, 200mA
CLDOB
2.2µF
VOUTB
1.8V, 200mA
2847.2008.05.1.2
www.analogictech.com
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