PRODUCT DATASHEET
AAT2845
ChargePump
TM
General Description
The AAT2845 is a highly integrated power solution for
single-cell lithium-ion-based LCD display applications. It
includes a four-channel LED backlight driver and two
integrated 200mA LDOs as additional power supplies for
display and camera-related chipsets.
The backlight driver is a low noise, constant frequency
charge pump DC/DC converter that uses a tri-mode load
switch (1X), fractional (1.5X), and doubling (2X) conver-
sion to maximize efficiency. Each of the four channels is
capable of driving up to 20mA per channel.
AnalogicTech’s S
2
Cwire™ (Simple Serial Control™) serial
digital input is used to enable, disable, and set current
for each LED with 16 available settings down to 50µA.
The low current mode supply current can be as low as
50µA to save power and maintain high efficiency.
Each LED output is equipped with built-in protection for
short-circuit and auto-disable functions. Built-in soft-
start circuitry prevents excessive inrush current during
start-up. A low current shutdown feature disconnects the
load from the input and reduces quiescent current to less
than 1µA.
The AAT2845 is available in a Pb-free, thermally-
enhanced 20-pin 3x4mm TQFN package.
Four-Channel Backlight Driver with Dual LDOs
Features
• Input Voltage Range: 2.7V to 5.5V
• Four-Channel LED Driver:
▪
Tri-Mode Charge Pump
▪
Up to 20mA/Channel
▪
Easy Control with Single Wire Interface
▪
16 Current Levels
▪
Four Low Current Settings Down to 50µA
▪
Low I
Q
(50µA) for Low Current Mode
▪
>90% Peak Efficiency
• Dual, 200mA LDOs
▪
User-Programmable Outputs: AAT2845-EE
▪
Fixed Output Voltages
• AAT2845-QG: 2.8V and 1.5V
• AAT2845-QI: 2.8V and 1.8V
• Automatic Soft-Start
• Over-Temperature Protection
• Available in 3x4mm TQFN34-20 Package
• -40°C to +85°C Temperature Range
Applications
•
•
•
•
Camera Function Power Supplies
Camera Phone Displays
LCD Modules
White LED Backlighting
Typical Application
CF1
1µF
C1-
CF2
1µF
C2+
CF1
1µF
C1-
CF2
1µF
C2+
C1+ C2-
C1+ C2-
OUT
IN
V
BAT
3.6V
OUT
C
OUT
1µF
AAT2845-EE
C
IN
2.2µF
WLEDs
OSRAM LW M673
or equivalent
IN
V
BAT
3.6V
AAT2845-QI
C
IN
2.2µF
C
OUT
1µF
WLEDs
OSRAM LW M673
or equivalent
D1
D2
D3
D4
IN
LDOA
200mA
C
OUTA
2.2µF
D1
D2
D3
D4
IN
LDOA
C
OUTA
2.2µF
V
OUTA
2.8V, 200mA
FBA
S
2
Cwire
Backlight Control
LDO Enable
C
BYP
0.1µF
EN/SET
LDOB
ENLDO
CBP
FBB
GND/PGND
200mA
C
OUTB
2.2µF
S
2
Cwire
Backlight Control
LDO Enable
C
BYP
0.1µF
EN/SET
LDOB
ENLDO
CBP
GND/PGND
C
OUTB
2.2µF
V
OUTB
1.8V, 200mA
2845.2008.05.1.2
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