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AAT3680ITP-4.2-T1 Schematic ( PDF Datasheet ) - Advanced Analogic Technologies

Teilenummer AAT3680ITP-4.2-T1
Beschreibung Lithium-Ion Linear Battery Charge Controller
Hersteller Advanced Analogic Technologies
Logo Advanced Analogic Technologies Logo 




Gesamt 18 Seiten
AAT3680ITP-4.2-T1 Datasheet, Funktion
AAT3680
Lithium-Ion Linear Battery Charge Controller
General Description
The AAT3680 BatteryManager™ is a member of
AnalogicTech's Total Power Management IC™
family. This device is an advanced Lithium-Ion (Li-
Ion) battery charge and management IC, specifi-
cally designed for low cost compact portable appli-
cations. In a single 8-pin package, the AAT3680
precisely regulates battery charge voltage and
charge current. This device is capable of two trick-
le charge current levels controlled by one external
pin. Battery charge temperature and charge state
are carefully monitored for fault conditions. In the
event of an over current, short circuit or over tem-
perature failure, the device will automatically shut
down, thus protecting the charging device and the
battery under charge. A battery charge state mon-
itor output pin is provided to indicate the battery
charge status though a display LED. The battery
charge status output is a serial interface which may
also be read by a system microcontroller.
The AAT3680 is available in an 8-pin MSOP or 12-
pin TSOPJW package, specified over -20 to 70°C
range.
Features BatteryManager
• 4.5V to 15V Input voltage range
• 1% Accurate Preset Voltages: 4.1V, 4.2V,
8.2V, 8.4V
• Low operation current, typically 0.5mA
• Programmable Charge Current
• Automatic recharge sequencing
• Battery temperature monitoring
• Deep discharge cell conditioning
• Fast trickle charge option with thermal over-ride
• Full battery charge auto turn off / sleep mode
• Over voltage, current and temperature
protection
• Power on reset
• LED Charge Status Output or System
Microcontroller serial interface
• Temperature range -20 to 70°C
• 8 pin MSOP, 12 pin TSOPJW package
Applications
• Cellular Phones
• Personal Digital Assistants (PDA's)
• Desktop Chargers
• USB Chargers
Typical Application
RSENSE
Q1
0.2
FZT788B
VP
C1
4.7µF
R1
2.5k
DRV
T2X
CSI BAT
AAT3680
VP TS
VSS
STAT
D1
R2
1k
BATT+
C2
10µF
VP
RT1
BATT-
TEMP
Battery
RT2 Pack
3680.2003.4.0.91
1






AAT3680ITP-4.2-T1 Datasheet, Funktion
AAT3680
Lithium-Ion Linear Battery Charge Controller
Constant Voltage Charging
When the battery's voltage reaches VCH during
constant-current mode, the AAT3680 transitions to
constant-voltage mode. The regulation voltage is
factory programmed: 4.1V and 4.2V (or 8.2V and
8.4V for two-cell applications) are available to sup-
port different anode materials in Lithium Ion cells.
In constant-voltage operation, the AAT3680 moni-
tors the cell voltage and terminates the charging
cycle when the voltage across RSENSE decreases to
approximately 10mV.
Charge Cycle Termination, Recharge
Sequence
After the charge cycle is complete, the AAT3680
latches off the pass device and automatically enters
power-saving sleep mode. Either of two possible
conditions will bring the IC out of sleep mode: the
battery voltage at the BAT pin drops below VRCH
(recharge threshold voltage) or the AAT3680 is reset
by cycling the input supply through the power-on
sequence. Falling below VRCH signals the IC that it
is time to initiate a new charge cycle.
PoPwoewr eOrnORneRseest et
UVLO
VP > VUVLO
No
SShMuhMtuoDtodDdeoewownn
Yes
TTemeFmpFaepuarelutarlttautruere
Temperature Test
No TS > VTS1
TS < VTS2
Yes
Preconditioning Test
VMIN > VBAT
Yes
No
Current Phase Test
VCH > VBAT
Yes
< VRCH
No
Voltage
Phase Test
VTERM
RSENSE
< IBAT
No
Yes
ChCaLhragaLtecraghCtecOohCmfOfopmflfeptleete
Low Current
CoLnodwitiConuirnregnt
CCohnadrigtieoning
(TrickleChCahragrege)
CCCMhCuMahorurarodrgerrdeigneneitngntg
CVCMhVoMahlootraaodlgtrgadeignegeigneg
Figure 1: AAT3680 Operational Flow Chart
6 3680.2003.4.0.91

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AAT3680ITP-4.2-T1 pdf, datenblatt
AAT3680
Lithium-Ion Linear Battery Charge Controller
Choosing a Sense Resistor
The charging rate recommended by Lithium Ion
cell vendors is normally 1C, with a 2C absolute
maximum rating. Charging at the highest recom-
mended rate offers the advantage of shortened
charging time without decreasing the battery's lifes-
pan. This means that the suggested fast charge
rate for a 500mAH battery pack is 500mA. The cur-
rent sense resistor, RSENSE, programs the charge
current according to the following equation:
RSENSE =
(VP -VCSI)
ICHARGE(REG)
Where ICHARGE(REG) is the desired typical charge cur-
rent during constant-current charge mode. VP-VCSI
is the voltage across RSENSE, shown in the Electrical
Characteristic table as VCS. To program a nominal
500mA charge current during fast-charge, a 200m
value resistor should be selected. Calculate the
worst case power dissipated in the sense resistor
according to the following equation:
P
=
(VCS)2
RSENSE
P
=
(0.1)2
0.2
P = 50mW
A 500mW LRC type sense resistor from IRC is
adequate for this purpose. Higher value sense
resistors can be used, decreasing the power dissi-
pated in the sense resistor and pass transistor.
The drawback of higher value sense resistors is
that the charge cycle time is increased, so tradeoffs
should be considered when optimizing the design.
Thermistor
The AAT3680 checks battery temperature before
starting the charge cycle as well as during all
stages of charging. This is accomplished by mon-
itoring the voltage at the TS pin. Either a negative-
temperature coefficient thermistor (NTC) or posi-
tive-temperature coefficient thermistor (PTC) can
be used because the AAT3680 checks to see that
the voltage at TS is within a voltage window bound-
ed by VTS1 and VTS2. Please see equations below
for specifying resistors:
RT1 and RT2 for use with NTC Thermistor
RT1 =
5 · RTH · RTC
3 · (RTC - RTH)
RT2 =
5 · RTH · RTC
(2 · RTC) - (7 · RTH)
RT1 and RT2 for use with PTC Thermistor
RT1 =
5 · RTH · RTC
3 · (RTC - RTH)
RT2 =
5 · RTH · RTC
(2 · RTH) - (7 · RTC)
Where RTC is the thermistor's cold temperature
resistance, and RTH is the thermistor's hot temper-
ature resistance. See thermistor specifications for
info. To ensure there is no dependence on the
input supply changes, connect divider between VP
and VSS. Disabling the temperature-monitoring
function is achieved by applying a voltage between
VTS1 and VTS2 on the TS pin.
Capacitor Selection
Input Capacitor
In general, it is good design practice to place a
decoupling capacitor between VP and VSS pins. An
input capacitor in the range of 0.1µF to 4.7µF is rec-
ommended. If the source supply is unregulated, it
may be necessary to increase the capacitance to
keep the input voltage above the undervoltage lock-
out threshold.
If the AAT3680 is to be used in a system with an
external power supply source, such as a typical AC to
DC wall adaptor, then a CIN capacitor in the range of
10µF should be used. A larger input capacitor in this
application will minimize switching or power bounce
effects when the power supply is "hot plugged" in.
12 3680.2003.4.0.91

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