AAT2552
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.
DH
Amp
.
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
Battery Charger
Functional Description
The battery charger is designed for single-cell lithi-
um-ion/polymer batteries using a constant current
and constant voltage algorithm. The battery charg-
er operates from the adapter/USB input voltage
range from 4V to 6.5V. The adapter/USB charging
current level can be programmed up to 500mA for
rapid charging applications. A status monitor out-
put 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 integrat-
ed reverse blocking diode and sense resistor.
The AAT2552 is a high performance power man-
agement IC comprised of a lithium-ion/polymer
battery charger, a step-down converter, and a lin-
ear regulator. The linear regulator is designed for
high-speed turn-on and fast transient response,
and good power supply ripple rejection. 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 switch-
ing frequency is reduced and the converter con-
sumes 45µA of current, making it ideal for battery-
operated applications.
2552.2007.04.1.0
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ANALOGICTECH [ ADVANCED ANALOGIC TECHNOLOGIES ]
