AAT2845 Datasheet, PDF (1/19 Pages) Advanced Analogic Technologies – Four-Channel Backlight Driver with Dual LDOs

AAT2845
Four-Channel Backlight Driver with Dual LDOs
General Description
Features
ChargePump^™
The AAT2845 is a highly integrated power solution
for single-cell lithium-ion-based LCD display appli-
cations. It includes a four-channel LED backlight
driver and two integrated 200mA LDOs as addi-
tional power supplies for display and camera-relat-
ed chipsets.
The backlight driver is a low noise, constant fre-
quency charge pump DC/DC converter that uses a
tri-mode load switch (1X), fractional (1.5X), and
doubling (2X) conversion to maximize efficiency.
Each of the four channels is capable of driving up
to 20mA per channel.
AnalogicTech's S²Cwire™ (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 protec-
tion for short-circuit and auto-disable functions.
Built-in soft-start circuitry prevents excessive
inrush current during start-up. A low current shut-
down feature disconnects the load from V_IN and
reduces quiescent current to less than 1µA.
The AAT2845 is available in a Pb-free, thermally-
enhanced 20-pin 3x4mm TQFN package.
• 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
• 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
VBAT
3.6V
C_IN
2.2µF
S²Cwire Backlight Control
LDO Enable
CBYP
0.1µF
CF1
CF2
1µF
1µF
C1- C1+ C2- C2+
IN
OUT
AAT2845
D1
D2
D3
D4
IN
LDOA
FBA
EN/SET
ENLDO
LDOB
CBP
GND ^FBB
COUT
1µF
200mA
Co1
200mA
Co2
2845.2006.12.1.0
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