AAT3686 AAT, AAT3686 Datasheet - Page 10

• Manufacturer Part Number: AAT3686
• Description: USB Port/AC Adapter Lithium-Ion/Polymer Battery Charger
• Manufacturer: AAT

Functional Block Diagram
Functional Description
The AAT3686 is a highly integrated single-cell lithium-
ion/polymer battery charger IC designed to operate
with USB port and AC adapter inputs, while requiring
a minimum number of external components. The
AAT3686 precisely regulates battery charge voltage
and current for 4.2V lithium-ion/polymer battery cells.
The adapter charge input constant current level can
be programmed up to 1.5A for rapid charging appli-
cations. In the absence of a high current adapter
input source, the AAT3686 can be powered from a
USB port V
type, the AAT3686 constant charge current can be
externally programmed for two levels, USB high and
USB low, for maximum constant current charge lev-
els up to 500mA. Typically, the USB charge levels
are set at 500mA and 100mA for the USBH and
USBL modes; however, the user may program
either mode to any level up to 500mA.
The USBH/L mode has automatic Charge Reduction
Loop control to allow users to charge the battery with
limited available current from a USB port, while
10
BUS
supply. Depending on the USB port
ADPSET
USBSEL
ADPP#
STAT1
STAT2
DATA
USBH
USBL
CHR
USB
ADP
EN
Voltage
Sense
Reduction
Charge
Loop
Charge
Status
Serial
Data
Constant
Compare
Compare
Current
Current
Current
IC enable
Lithium-Ion/Polymer Battery Charger
GND
maintaining the regulated port voltage. This system
assures the battery charge function will not overload
a USB port while charging if other system demands
also share power with the respective port supply.
The USB charge function is automatically disabled
when an adapter input power source greater than
4.4V is present.
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 22 various status states to a microcontroller.
Battery temperature and charge state are fully mon-
itored for fault conditions. In the event of an over-
voltage or over-temperature failure, the device will
automatically shut down, thus protecting the charg-
ing device, control system, and the battery under
charge. In addition to internal charge controller ther-
mal protection, the AAT3686 also provides a tem-
perature sense feedback function (TS pin) from the
battery to shut down the device in the event the bat-
tery 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.
Control
Charge
Reverse Blocking
Reverse Blocking
Window
Comparator
Watchdog
Timer
Temperature
Precharge
Protect
UVLO
Over-
CV/
USB Port/AC Adapter
80µA
BAT
CT
TS
3686.2006.10.1.9