AAT3691 Datasheet, PDF (9/18 Pages) Skyworks Solutions Inc. – Dual Input 1.6A Linear Charger with 28V OVP in a 3x4 TDFN Package

DATA SHEET
AAT3691
Dual Input 1.6A Linear Charger with 28V OVP in a 3x4 TDFN Package
Functional Block Diagram
USB
USBCH
USBSET
EN
OVP Switch
OVP Sense
and Control
ADPSET
Reverse Blocking
Current
Compare
Current
Compare
Charge
Control
CV/Precharge
UVLO
Over-Temp.
Protect
BAT
NOBAT
IC
ADPCH
ADP
OVP Sense
and Control
Charge
Status
Reverse Blocking
STAT
GND
Functional Description
The AAT3691 is a high performance battery charger
designed to charge single cell Lithium Ion or Polymer
batteries with up to 1600mA charging current from an
adaptor (ADP) power source, or with up to 500mA
charging current from an USB power source. The
AAT3691 is a stand-alone charging solution, with just a
few external component required for complete function-
ality. Both input paths include a fast turn-off over-volt-
age protection (OVP) circuit with voltage up to +28V and
an under-voltage lockout level of 3.0V.
The AAT3691 automatically selects the charging source
from USB or ADP according to ADP and USB voltage. The
ADP path is always the high priority charging path when
ADP voltage is higher than 4.5V. The charging current is
determined by the selected charging path and its exter-
nal set resistor (R_SET).
USB charging uses an automatic charge reduction loop
control allow battery charging with limited available cur-
rent from a USB port while maintaining the regulated
port voltage. This system assures that 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.
During adapter charging, high set charging current or
high ambient operating temperature may cause the
AAT3691 junction temperature to rise up to 110°C. A
special digital thermal loop control system is employed
to maximize charging current by dynamically decreasing
the battery charging current.
Thermal protection shuts down the AAT3691's charging
function when internal dissipation becomes excessive,
while OVP function still works. The junction over-temper-
ature threshold is 140°C with 15°C of hysteresis. Once
an over-temperature condition is removed, the charging
function automatically recovers.
The status monitor output pin (STAT) is designed to indi-
cate the battery charge status with open-drain structure
by directly driving one external LED.
Battery Charging Operation
Regardless of which charge input function is selected
(adapter input or USB input), the AAT3691 has three
basic modes for the battery charge cycle: precondition-
ing (trickle) charge, constant current/fast charge, and
constant voltage charge. When no automatic charge
reduction mode or digital thermal loop is triggered, the
charge profile is controlled as shown in Figure 1.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [e-mail] • www.skyworksinc.com
201894B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • April 27, 2012
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