AAT3663 Datasheet, PDF (17/22 Pages) Advanced Analogic Technologies – 1A Linear Li-Ion Battery Charger for Single and Dual Cell Applications

AAT3663
1A Linear Li-Ion Battery Charger
for Single and Dual Cell Applications
voltage below than the TS1 threshold, and indicate
a battery cell temperature fault. The charging
process will then be suspended until the over-tem-
perature condition is removed, at which time
charging will resume. Conversely, if the battery
under charge is exposed to extreme cold ambient
temperature condition, the NTC thermistor may
increase in value and push the voltage on the TS
pin above the TS2 threshold. In such a case, the
charge cycle will be suspended and will not resume
until the cold fault condition is removed. Both TS1
and TS2 temperature fault conditions will be report
by the STAT1 and STAT2 LEDs.
AAT3663-1 Option
the AAT3663-1 option utilizes an internal battery
temperature sensing system comprised of two com-
parators which establish a voltage window for safe
operation. The thresholds for the TS operating win-
dow are bounded by the TS1 and TS2 specifica-
tions. Referring to the electrical characteristics table
in this datasheet, the TS1 threshold = 0.30 · V_IN and
the TS2 threshold = 0.6 · V_IN. Refer to Figure 4 for
external resistor and NTC thermistor connections.
If the use of the battery temperature sense function
is not required, it may be disabled by terminating
the TS pin to IN and ground using a 10kΩ resistor
divider network. If circuit power dissipation is a
concern, the two terminating resistor values may
be increased to 100kΩ.
VIN
AAT3663-2 Option
Most of the commonly used NTC thermistors in Li-
Ion/Polymer battery packs are approximately 10kΩ
at room temperature (25°C). The AAT3663-2 TS
pin has been specifically designed to source 75µA
of current to the 10kΩ NTC thermistor. The applied
constant current source and fixed internal TS1 and
TS2 voltage thresholds eliminate the need for a
resistor divider on the TS pin. Simply connect the
10kΩ NTC resistor between the TS pin and ground.
If the TS function is not needed for the AAT3663-2,
it may be left open (not connected).
Thermal Considerations
The AAT3663 is offered in a 3x3mm TDFN package
which can provide up to 2.0W of power dissipation
when it is properly bonded to a printed circuit board
and has a maximum thermal resistance of 50°C/W.
Many considerations should be taken into account
when designing the printed circuit board layout, as
well as the placement of the charger IC package in
proximity to other heat generating devices in a given
application. The ambient temperature around the
charger IC will also have an effect on the thermal lim-
its of the battery charging operation. The maximum
limits that can be expected for a given ambient con-
dition can be estimated by the following discussion.
IN
R_T
TS
AAT3663-4.2-1 or AAT3663-8.4-1
0 .6xV IN
Battery Cold Fault
Battery
Pack
R_NTC
T
0. 30xVIN
Battery Hot Fault
Figure 4: External Resistor and NTC Thermistor Application Circuit.
3663.2007.10.1.0
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