AAT2552_08 Datasheet, PDF (14/31 Pages) Advanced Analogic Technologies – Total Power Solution for Portable Applications

SystemPower^TM
Functional Block Diagram
ADP
ISET
STAT
Current Compare
Constant Current
Charge Status
PRODUCT DATASHEET
AAT2552178
Total Power Solution for Portable Applications
Reverse Blocking
Charge
Control
CV/Pre-Charge
UVLO
BAT
FBB
INB
EN_BAT
ENB
MODE
INA
ENA
Voltage
Reference
Input
Err.
Amp
.
From
Charger Section
Over-Temperature
Protection
DH
Logic
DL
Fast Start
Control
Active Feedback
Control
+
Err.
Amp
-
Over-Current
Protection
Voltage
Reference
LX
PGND
OUTA
FBA
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.
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
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.
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-
14
www.analogictech.com
2552.2008.02.1.2