AAT3686_08 Datasheet, PDF (10/23 Pages) Advanced Analogic Technologies – USB Port/AC Adapter Lithium-Ion/Polymer Battery Charger

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PRODUCT DATASHEET
AAT3686
USB Port/AC Adapter Lithium-Ion/Polymer Battery Charger
Functional Block Diagram
USB
USBSEL
USBH
USBL
CHR
ADPSET
ADP
ADPP#
STAT1
STAT2
DATA
EN
Reverse Blocking
Charge
Reduction
Loop
Current
Compare
Constant
Current
Current
Compare
Charge
Control
CV/
Precharge
UVLO
Over-
Temperature
Protect
BAT
Voltage
Sense
Charge
Status
Serial
Data
Reverse Blocking
80µA
IC enable
Window
Comparator
Watchdog
Timer
TS
CT
GND
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 mini-
mum 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 applications.
In the absence of a high current adapter input source,
the AAT3686 can be powered from a USB port VBUS sup-
ply. Depending on the USB port type, the AAT3686 con-
stant charge current can be externally programmed for
two levels, USB high and USB low, for maximum con-
stant current charge levels 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 maintaining the
regulated port voltage. This system assures the battery
charge function will not overload a USB port while charg-
ing if other system demands also share power with the
respective port supply. The USB charge function is auto-
matically 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 moni-
tored for fault conditions. In the event of an over-voltage
or over-temperature failure, the device will automati-
cally shut down, thus protecting the charging device,
control system, and the battery under charge. In addi-
tion to internal charge controller thermal protection, the
AAT3686 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.
Charging Operation
Regardless of which charge input function is selected
(i.e., either the adapter input or USB input), the AAT3686
has four basic modes for the battery charge cycle: pre-
conditioning/trickle charge; constant current/fast charge;
constant voltage; and end of charge (see Figure 1).
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