AAT3685 Datasheet, PDF (10/23 Pages) Advanced Analogic Technologies – Lithium-Ion/Polymer Battery Charger

AAT3685
Lithium-Ion/Polymer Battery Charger
Functional Block Diagram
ADP/USB
PWRSEL
SETH
SETL
CHR
STAT1
STAT2
DATA
Charge
Reduction
Loop
Current
Compare
Constant
Current
Charge
Status
Reverse Blocking
Charge
Control
CV/
Precharge
UVLO
Over-
Temperature
Protect
BAT
Serial
Data
IC enable
Window
Comparator
80μA
TS
EN
GND
Functional Description
The AAT3685 is a highly integrated single cell lithi-
um-ion/polymer battery charger IC designed to
operate from adapter or USB port V_BUS supplies,
while requiring a minimum number of external
components. The device precisely regulates bat-
tery charge voltage and current for 4.2V lithium-
ion/polymer battery cells.
The AAT3685 is specifically designed for being
powered from a USB port V_BUS supply, but it can
also be powered from any input voltage source
capable supplying 4.5V to 5.5V for loads up to 1A.
The AAT3685 constant charge current can be
externally programmed for two levels, SETH and
SETL, for maximum constant current charge levels
up to 1A. The SETH/L mode has an automatic
Charge Reduction Loop control to allow users to
charge the battery with limited available current
from a port while maintaining the regulated port
voltage. This system assures the battery charge
function will not overload the port while charging if
other system demands also share power with the
respective port supply.
Status monitor output pins are provided to indicate
the battery charge status by directly driving two
external LEDs. A serial interface output is available
to report 14 various charge states to a system
microcontroller.
Battery temperature and charge state are fully
monitored for fault conditions. In the event of an
over-voltage or over-temperature failure, the
device will automatically shut down, thus protecting
the charging device, control system, and the bat-
tery under charge. In addition to internal charge
controller thermal protection, the AAT3685 also
provides a temperature sense feedback function
(TS pin) from the battery to shut down the device in
the event the battery exceeds its own thermal limit
during charging. All fault events are reported to the
user either by the simple status LEDs or via the
DATA pin function.
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3685.2006.10.1.3