PRODUCT DATASHEET
AAT2848
TM
ChargePump
High-Current Charge Pump For Backlight Display and Flash Applications
General Description
Features
The AAT2848 is a tri-mode charge pump optimized for
systems operating with lithium-ion/polymer batteries. The
charge pump provides power for both white LED backlight
and flash, with an integrated four channel backlight LED
current sink plus two channel flash LED current sinks.
• Tri-Mode (1x/1.5x/2x) Charge Pump
• Four 30mA Backlight LED Channels
• Independent S2Cwire Control for Backlight
• 32-Level Programmable Backlight Current Control—
Linear, Inverting
• Two 300mA Flash LED Channels
• Independent S2Cwire Control for Flash
• 16-Level Programmable Flash Current Control—
Linear, Inverting
• User-Programmable Full Scale Current for Backlight
and Flash
• User-Programmable Fade-In/Fade-Out Function for
Backlight
• User-Programmable Safety Timer for Flash LED
Protection
Each backlight channel can drive up to 30mA, while each
flash current sink/channel can drive up to 300mA (600mA
total). Two independent S2Cwire™ (AnalogicTech’s Simple
Serial Control™) serial digital interface inputs enable,
disable, and set LED current to one of 32 levels for the
backlight and to one of 16 levels for the flash, with full-
scale current independently set for backlight and flash
using external resistors.
The AAT2848 offers a built-in fade-in/out function for
linear control of the backlight current during ON/OFF
transitions. The fade time is programmable by an exter-
nal capacitor.
• Built-In Thermal Protection
• Automatic Soft-Start
• -40°C to +85°C Temperature Range
• Available in TQFN33-20 Package
The AAT2848 also offers a built-in flash timeout function
as a safety feature associated with the high power flash
driver. The safety timer is also programmable via an
external capacitor.
Applications
• Camera Enabled Mobile Devices
• Digital Still Cameras
The AAT2848 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 AAT2848 is available in a Pb-free, space
saving TQFN33-20 package and operates over the -40°C
to +85°C ambient temperature range.
• Multimedia Mobile Phones
Typical Application
C1
1μF
C2
1μF
WLEDs
OSRAM LW M673
or equivalent
C1+
C1-
C2- C2+
OUT
IN
Flash LEDs
Lumileds PWF1
COUT
VBAT
CIN
4.7μF
or equivalent
2.2μF
AAT2848
BL1
S2Cwire
BL2
BL3
BL4
BENS
FENS
Backlight Control
S2Cwire
Flash Control
FL1
FL2
BSET
FSET
RBSET
15k
RFSET
14.3k
FLTMR
FADE
AGND
CFLTMR
330nF
CFADE
47nF
PGND
w w w . a n a l o g i c t e c h . c o m
2848.2008.05.1.0
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