Total Power Solution for Portable Applications
General Description
The AAT2550 is a fully integrated total power solu-
tion with two step-down converters plus a single-
cell lithium-ion / polymer battery charger. The step-
down converter input voltage range spans 2.7V to
5.5V, making the AAT2550 ideal for systems pow-
ered by single-cell lithium-ion/polymer batteries.
The battery charger is a complete constant current/
constant voltage linear charger. It offers an inte-
grated pass device, reverse blocking protection,
high current accuracy and voltage regulation,
charge status, and charge termination. The charg-
ing current is programmable via external resistor
from 100mA to 1A. In addition to these standard
features, the device offers over-voltage, over-cur-
rent, and thermal protection.
The two step-down converters are highly integrated,
operating at a switching frequency of 1.4MHz, mini-
mizing the size of external components while keep-
ing switching losses low. Each converter has inde-
pendent input, enable, and feedback pins. The out-
put voltage ranges from 0.6V to V
IN
. Each converter
is capable of delivering up to 600mA of load current.
The AAT2550 is available in a Pb-free, space-sav-
ing, thermally-enhanced QFN44-24 package and is
rated over the -40°C to +85°C temperature range.
AAT2550
Features
•
SystemPower
™
•
•
•
•
Two Step-Down Converters:
— 600mA Output Current per Converter
— V
IN
Range: 2.7V to 5.5V
— 1.4MHz Switching Frequency
— Low R
DS(ON)
0.4Ω Integrated Power
Switches
— Internal Soft Start
— 27µA Quiescent Current per Converter
Highly Integrated Battery Charger:
— Programmable Charging Current from
100mA to 1A
— Pass Device
— Reverse Blocking Diodes
— Current Sensing Resistor
— Digital Thermal Regulation
Short-Circuit, Over-Temperature, and Current
Limit Protection
QFN44-24 Package
-40°C to +85°C Temperature Range
Applications
•
•
•
•
•
Cellular Telephones
Digital Cameras
Handheld Instruments
MP3, Portable Music, and Portable Media
Players
PDAs and Handheld Computers
Typical Application
Battery Pack
Adapter
ADP
BAT
Batt+
AAT2550
STAT1
STAT2
Serial Interface
R
SET
TS
Batt-
DATA
ADPSET
CT
Temp
ENBAT
INA
Li-Ion Battery or
Adapter
LXA
FBA
LXB
FBB
GND
V
OUTA
C
OUTA
INB
ENA
ENB
V
OUTB
C
OUTB
2550.2006.07.1.0
1
ANALOGICTECH [ ADVANCED ANALOGIC TECHNOLOGIES ]
