AAT2856_08 Datasheet, PDF (1/18 Pages) Advanced Analogic Technologies – High Current Charge Pump with Dual LDO for Backlight Applications

PRODUCT DATASHEET
AAT2856
ChargePump^TM High Current Charge Pump with Dual LDO for Backlight Applications
General Description
The AAT2856 is a highly integrated charge pump with
dual linear regulators optimized for systems powered
from lithium-ion/polymer batteries. The charge pump
provides power for white LED backlight. Six backlight
LEDs can be driven at up to 30mA. AnalogicTech’s
AS²Cwire™ (Advanced Simple Serial Control™) single-
wire interface is used to enable, disable, and set the
current to one of 32 levels for the backlight. Backlight
current matching is 1% for uniform display brightness.
The AAT2856 offers two high-performance low-noise
MicroPower™ low dropout (LDO) linear regulators. Both
regulators use individual enable inputs and each will
supply up to 200mA load current. LDO ground pin cur-
rent is only 80μA, making the AAT2856 ideal for battery-
operated applications.
The AAT2856 is equipped with built-in short-circuit and
over-temperature protection. The soft start circuitry pre-
vents excessive inrush current at start-up and mode
transitions.
The AAT2856 is available in a Pb-free TQFN44-28 pack-
age and operates over the -40°C to +85°C ambient
temperature range.
Features
• Input Voltage Range: 2.7V to 5.5V
• Tri-Mode Charge Pump:
▪ Drives up to Six Backlight LEDs
▪ 32 Programmable Backlight Current Settings
Ranging from 115μA to 30mA
▪ 2MHz Switching Frequency
• Two Linear Regulators:
▪ 200mA Output Current
▪ 200mV Dropout Voltage
▪ Output Voltage Adjustable from 1.2V to VBATTERY
▪ ^{Output Auto-Discharge for Fast Shutdown}
▪ Individual LDO Enable Inputs
• Built-In Thermal Protection
• Automatic Soft Start
• -40°C to +85°C Temperature Range
• TQFN44-28 Package
Applications
• Camera-Enabled Mobile Devices
• Digital Still Cameras
• Multimedia Mobile Phones
Typical Application
VBAT
C_IN
4.7μF
ENABLE/SET
CBYP
0.1μF
EN_LDOA
EN_LDOB
C1
C₂
1μF
1μF
C1+ C1-
IN
C2+ C2-
OUT
IN
BL1
BL2
BL3
AAT2856 BL4
BL5
BL6
ENS
REF
OUTA
FBA
ENA
ENB
AGND
OUTB
FBB
PGND
COUT
2.2μF
V_OUT
WLEDs
OSRAM LW M673
or equivalent
VOUTA
R2A
C_OUTA
R_1A
2.2μF
V_OUTB
R_2B
COUTB
R_1B
2.2μF
2856.2008.02.1.3
www.analogictech.com
1