AAT3693 Advanced Analogic Technologies, Inc., AAT3693 Datasheet - Page 16

• Manufacturer Part Number: AAT3693
• Description: 1.6a Lithium-ion/polymer Battery Charger In 2.2x2.2 Tdfn
• Manufacturer: Advanced Analogic Technologies, Inc.

Battery Over-Voltage Protection
An over-voltage event is defined as a condition where the
voltage on the BAT pin exceeds the maximum battery
charge voltage and is set by the overvoltage protection
threshold (V
AAT3693 charge control will shut down the device until
the voltage on the BAT pin drops below V
will resume normal charging operation after the overvolt-
age condition is removed. During an over-voltage event,
the STAT1 LED will report a system fault.
Over-Temperature Shutdown
The AAT3693 has a thermal protection control circuit
which will shut down charging functions should the inter-
nal die temperature exceed the preset thermal limit
threshold. Once the internal die temperature falls below
the thermal limit, normal operation will resume the pre-
vious charging state.
Battery Temperature Fault Monitoring
In the event of a battery over-temperature condition, the
charge control will turn off the internal pass device.. The
STAT LEDs will also display a system fault. After the sys-
tem recovers from a temperature fault, the device will
resume charging operation.
The AAT3693 checks battery temperature before starting
the charge cycle, as well as during all phases of charging.
This is accomplished by monitoring the voltage at the TS
pin. This system is intended for use with negative tem-
perature coefficient thermistors (NTC) which are typically
integrated into the battery package. Most of the com-
monly used NTC thermistors in battery packs are approx-
imately 10kΩ at room temperature (25°C).
For options AC, AD, AG, AH, AK, AL, BO, and BP, the TS
pin has been specifically designed to source 75μA of cur-
rent to the thermistor. The voltage on the TS pin result-
ing from the resistive load should stay within a window
of 331mV to 2.39V. If the battery becomes too hot dur-
ing charging due to an internal fault or excessive con-
stant charge current, the thermistor will heat up and
reduce in value, pulling the TS pin voltage lower than the
TS1 threshold, and the AAT3693 will stop charging until
the condition is removed, then charging will be
resumed.
16
BatteryManager
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). If an over-voltage condition occurs, the
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1.6A Lithium-Ion/Polymer Battery Charger in 2.2x2.2 TDFN
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. The AAT3693
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If the use of the TS pin function is not required by the
system, it should be terminated to ground using a 10kΩ
resistor. The internal battery temperature sensing sys-
tem is comprised of two comparators which establish a
voltage window for safe operation.
For options AA, AB, AE, AF, AI, AJ, BM, and BN, the
thresholds for the TS operating window are bounded by
the TS1 and TS2 specifications. Referring to the electrical
characteristics table in this datasheet, the TS1 threshold
= 0.30 · V
Digital Thermal Loop Control
Due to the integrated nature of the linear charging con-
trol pass device for the adapter mode, a special thermal
loop control system has been employed to maximize
charging current under all operation conditions. The
thermal management system measures the internal cir-
cuit die temperature and reduces the fast charge current
when the device exceeds a preset internal temperature
control threshold. Once the thermal loop control becomes
active, the fast charge current is initially reduced by a
factor of 0.44.
The initial thermal loop current can be estimated by the
following equation:
Figure 4: Battery Temperature Sensing Operation.
Battery
Pack
IN
and the TS2 threshold = 0.60 · V
V
IN
AAT3693-AA, AB, AE, AF, AI, AJ, BM, BN
TS
IN
Battery Temperature Sense Circuit
I
TLOOP
PRODUCT DATASHEET
0.60x V
= I
x V
CC
IN
IN
AAT3693
• 0.44
Battery Cold Fault
Battery Hot Fault
3693.2009.04.1.1
IN
.