PRODUCT DATASHEET
AAT2552178
SystemPowerTM
Total Power Solution for Portable Applications
Functional Block Diagram
Reverse Blocking
ADP
BAT
Current Compare
CV/Pre-Charge
Charge
Control
Constant Current
ISET
UVLO
STAT
FBB
INB
Charge Status
EN_BAT
Err.
Amp
.
DH
LX
Voltage
Reference
Logic
DL
ENB
Input
MODE
PGND
OUTA
Over-Temperature
Protection
From
Charger Section
INA
Active Feedback
Control
Over-Current
Protection
Err.+
FBA
Amp
Voltage
Reference
Fast Start
Control
-
ENA
AGND
adapter/USB input voltage range from 4V to 7.5V. The
adapter/USB charging current level can be programmed
up to 500mA for rapid charging applications. A status
monitor output pin is provided to indicate the battery
charge state by directly driving one external LED. Internal
device temperature and charging state are fully monitored
for fault conditions. In the event of an over-voltage or
over-temperature failure, the device will automatically
shut down, protecting the charging device, control system,
and the battery under charge. Other features include an
integrated reverse blocking diode and sense resistor.
Functional Description
The AAT2552 is a high performance power man-agement
IC comprised of a lithium-ion/polymer battery charger, a
step-down converter, and a linear regulator. The linear
regulator is designed for high-speed turn-on and fast
transient response, and good power supply ripple rejec-
tion. The step-down converter operates in both fixed and
variable frequency modes for high efficiency performance.
The switching frequency is 1.5MHz, minimizing the size of
the inductor. In light load conditions, the device enters
power-saving mode; the switching frequency is reduced
and the converter consumes 45μA of current, making it
ideal for battery-operated applications.
Switch-Mode Step-Down Converter
The step-down converter operates with an input voltage
of 2.7V to 5.5V. The switching frequency is 1.5MHz,
minimizing the size of the inductor. Under light load
conditions, the device enters power-saving mode; the
switching frequency is reduced, and the converter con-
Battery Charger
The battery charger is designed for single-cell lithium-ion/
polymer batteries using a constant current and constant
voltage algorithm. The battery charger operates from the
w w w . a n a l o g i c t e c h . c o m
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2552.2008.02.1.2
ANALOGICTECH [ ADVANCED ANALOGIC TECHNOLOGIES ]
