AAT AAT3685IWP-4.2-T1 Lithium-ion/polymer battery charger Datasheet

AAT3685
Lithium-Ion/Polymer Battery Charger
General Description
Features
The AAT3685 BatteryManager™ is a highly integrated single cell lithium-ion/polymer battery charger IC designed to operate with USB port or line
adapter inputs. It requires the minimum number of
external components.
•
•
•
The AAT3685 precisely regulates battery charge voltage and current for 4.2V lithium-ion/polymer battery
cells. Regardless of the type of input power source
(USB or adapter), the AAT3685 can be programmed
for two separate constant current charge levels up to
1A. An optional Charge Reduction Loop is built in to
allow users to charge the battery with available current from the charge supply, while keeping the port
voltage regulated.
•
•
•
•
•
•
•
•
•
Battery temperature and charge state are fully
monitored for fault conditions. In the event of an
over-voltage or over-temperature failure, the
device will automatically shut down, thus protecting
the charging device, control system, and the battery under charge. 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 any one of 14 various
status states to a microcontroller.
BatteryManager™
Adapter or USB Charger
— Programmable up to 1A Max
4.0V to 5.5V Input Voltage Range
High Level of Integration With Internal:
— Charging Device
— Reverse Blocking Diode
— Current Sensing
Automatic Recharge Sequencing
Charge Reduction Loop
Battery Temperature Monitoring
Full Battery Charge Auto Turn-Off
Over-Voltage Protection
Emergency Thermal Protection
Power On Reset and Soft Start
Serial Interface Status Reporting
12-Pin 3x3mm TDFN Package
Applications
•
•
•
•
•
•
The AAT3685 is available in a Pb-free, thermallyenhanced, space-saving 12-pin 3x3mm TDFN
package and is rated over the -40°C to +85°C temperature range.
Cellular Telephones
Digital Still Cameras
Hand-Held PCs
MP3 Players
Personal Data Assistants (PDAs)
Other Lithium-Ion/Polymer Battery-Powered
Devices
Typical Application
Enable
Adapter or USB Input
ADP/USB
Input Hi/Lo Select
PWRSEL
RSETH
RSETL
EN
CHR
BATT+
SETH
BAT
SETL
TS
AAT3685
C2
10μF
BATT-
GND
DATA
STAT1
TEMP
STAT2
Battery Pack
Serial Data
3685.2006.10.1.3
1
AAT3685
Lithium-Ion/Polymer Battery Charger
Pin Descriptions
Pin #
Name
Type
1
2
3
4
ADP/USB
BAT
GND
CHR
In
In/Out
Ground
In/Out
5
6
7
8
9
10
EN
TS
DATA
STAT2
STAT1
PWRSEL
In
In/Out
In/Out
Out
Out
In
11
12
EP
SETL
SETH
In/Out
In/Out
Function
Line adapter or USB power supply input.
Battery charging and sensing.
Ground connection.
Resistor divider to set USB voltage regulation for charge reduction mode.
Leave this pin open for default 4.5V USB regulation point. Tie to ADP/USB
pin to disable this function.
Enable pin. Logic high enables the IC.
Connect to 10kΩ NTC thermistor.
Status report to microcontroller via serial interface, open-drain.
Battery charge status indicator pin to drive an LED: active low, open-drain.
Battery charge status indicator pin to drive an LED: active low, open-drain.
When ADP/USB is present, use this pin to toggle between SETH and SETL
charging levels.
Connect resistor here to set charge current for low-current port.
Connect resistor here to set charge current for high-current port.
Exposed paddle (bottom); connect to GND directly beneath package.
Pin Configuration
TDFN33-12
(Top View)
ADP/USB
BAT
GND
CHR
EN
TS
2
1
12
2
11
3
10
4
9
5
8
6
7
SETH
SETL
PWRSEL
STAT1
STAT2
DATA
3685.2006.10.1.3
AAT3685
Lithium-Ion/Polymer Battery Charger
AAT3685 Feature Options
Product
Internal Pull-Up
Resistor on EN Pin
Can Leave
TS Pin Open
AAT3685
AAT3685-1
No
Yes
No
Yes
Absolute Maximum Ratings1
Symbol
VP
VP
VN
TJ
TLEAD
Description
ADP/USB Input Voltage, <30ms, Duty Cycle <10%
ADP/USB Input Voltage, Continuous
BAT, PWRSEL, SETH, SETL, STAT1, STAT2, DATA, TS, CHR, EN
Operating Junction Temperature Range
Maximum Soldering Temperature (at leads)
Value
Units
-0.3 to 7.0
-0.3 to 6.0
-0.3 to VP + 0.3
-40 to 150
300
V
V
V
°C
°C
Value
Units
50
2.0
°C/W
W
Thermal Information2
Symbol
θJA
PD
Description
Maximum Thermal Resistance (3x3mm TDFN)
Maximum Power Dissipation
1. Stresses above those listed in Absolute Maximum Ratings may cause permanent damage to the device. Functional operation at conditions other than the operating conditions specified is not implied. Only one Absolute Maximum Rating should be applied at any one time.
2. Mounted on an FR4 board.
3685.2006.10.1.3
3
AAT3685
Lithium-Ion/Polymer Battery Charger
Electrical Characteristics1
VADP = 5V, TA = -25°C to +85°C, unless otherwise noted. Typical values are at TA = 25°C.
Symbol
Operation
ADP/USB
VUVLO
IOP
ISLEEP
Description
Input Voltage Range
Under-Voltage Lockout
Under-Voltage Lockout Hysteresis
Operating Current
Sleep Mode Current
Reverse Leakage Current from
BAT Pin
Voltage Regulation
VBAT_EOC1 End of Charge Voltage Accuracy
ΔVBAT/VBAT EOC Voltage Tolerance
VMIN
Preconditioning Voltage Threshold
VRCH
Battery Recharge Voltage Threshold
VADP/USB_CHR Charge Reduction Regulation
VCHR
CHR Pin Voltage Accuracy
Current Regulation
ICH
Charge Current
Charge Current Regulation
ΔICH/ICH
Tolerance
VSETH
SETH Pin Voltage
VSETL
SETL Pin Voltage
KIUH
Current Set Factor: ICHARGE/ISETH
KIUL
Current Set Factor: ICHARGE/ISETL
Charging Devices
Charging MOSFET Transistor
RDS(ON)U
On Resistance
ILeakage
Conditions
Min
Typ
4.0
Rising Edge
2.8
4.2
0.5
3.0
4.3
1.9
VBAT_EOC - 0.1
4.5
2.0
50
CC Mode
CC Mode
VIN = 5.5V
1.5
1.0
3
1.0
4.158
No Connection on CHR Pin
5.5
3.0
150
0.75
0.3
1
CC Charge Current = 500mA
AAT3685: VBAT = 4.25V
AAT3685-1: VBAT = 4.25V
VBAT = 4V, ADP/USB Pin
Open
Max Units
0.4
V
V
mV
mA
μA
μA
4.242
4.64
2.1
V
%
V
V
V
V
1000
mA
3.15
10
%
2.0
2.0
2000
2000
V
V
0.5
0.65
Ω
1. The AAT3685 output charge voltage is specified over the 0° to 70°C ambient temperature range; operation over the -25°C to +85°C
temperature range is guaranteed by design.
4
3685.2006.10.1.3
AAT3685
Lithium-Ion/Polymer Battery Charger
Electrical Characteristics1
VADP = 5V, TA = -25°C to +85°C, unless otherwise noted. Typical values are at TA = 25°C.
Symbol
Description
Logic Control / Protection
VPWRSEL(H) Input High Threshold
VPWRSEL(L) Input Low Threshold
VEN(H)
Input High Threshold
VEN(L)
Input Low Threshold
IEN(H)
EN Input Current
VSTAT
Output Low Voltage
ISTAT
STAT Pin Current Sink Capability
VOVP
Over-Voltage Protection Threshold
ITK/ICHG
ITERM/ICHG
ITERM/ICHG
ITS
Pre-Charge Current
Charge Termination Threshold Current
Charge Termination Threshold Current
Current Source from TS Pin
TS1
TS Hot Temperature Fault
TS2
TS Cold Temperature Fault
I_DATA
VDATA(H)
VDATA)(L)
SQPULSE
tPERIOD
fDATA
TOVSD
DATA Pin Sink Current
Input High Threshold
Input Low Threshold
Status Request Pulse Width
System Clock Period
Data Output Frequency
Over-Temperature Shutdown Threshold
Conditions
Min Typ
Max
1.6
0.4
1.6
0.4
10
0.4
AAT3685-1 Only, VEN = 5V
STAT Pin Sinks 4mA
For
For
For
For
SETH Mode
SETL Mode
SETH Mode
SETL Mode
Threshold
Hysteresis
Threshold
Hysteresis
DATA Pin is Active Low State
70
310
2.2
8.0
4.4
10
50
7.5
35
80
330
15
2.3
10
90
350
2.4
3.0
1.6
200
50
20
145
V
V
V
V
μA
V
mA
V
%
0.4
Status Request
Units
%
%
μA
mV
V
mV
mA
V
V
ns
μs
kHz
°C
1. The AAT3685 output charge voltage is specified over the 0° to 70°C ambient temperature range; operation over the -25°C to +85°C
temperature range is guaranteed by design.
3685.2006.10.1.3
5
AAT3685
Lithium-Ion/Polymer Battery Charger
Typical Characteristics
IFASTCHARGE vs. RSET
Battery Voltage vs. Supply Voltage
4.242
4.221
1000
VBAT (V)
IFASTCHARGE (mA)
10000
SETL
100
10
SETH
1
4.200
4.179
10
100
4.158
1000
4.5
4.75
5
5.25
5.5
Supply Voltage (V)
RSET (kΩ)
Recharge Voltage vs. Temperature
End of Charge Voltage vs. Temperature
4.242
4.140
4.130
4.120
4.221
4.100
VBAT (V)
VRCH (V)
4.110
4.090
4.080
4.070
4.200
4.179
4.060
4.050
4.040
-50
-25
0
25
50
75
4.158
100
-50
-25
Temperature (°C)
0
25
50
75
100
Temperature (°C)
Preconditioning Threshold
Voltage vs. Temperature
Preconditioning Charge Current vs. Temperature
(SETH; SETH = 3.83kΩ
Ω)
3.05
120
3.04
3.03
110
ICH (mA)
VMIN (V)
3.02
3.01
3.00
2.99
2.98
100
90
2.97
2.96
2.95
80
-50
-25
0
25
50
Temperature (°C)
6
75
100
-50
-25
0
25
50
75
100
Temperature (°C)
3685.2006.10.1.3
AAT3685
Lithium-Ion/Polymer Battery Charger
Typical Characteristics
Charging Current vs. Battery Voltage
Fast Charge Current vs. Temperature
(SETH; SETH = 3.83kΩ
Ω)
(SETH; SETH = 3.83kΩ)
1200
1100
1080
1000
1060
800
ICH (mA)
ICH (mA)
1040
1020
1000
980
960
940
600
400
200
920
0
900
-50
-25
0
25
50
75
100
2.5
3
Charging Current vs. Battery Voltage
4.5
Fast Charge Current vs. Supply Voltage
(SETL; SETL = 40.2kΩ
Ω)
(SETH; SETH = 3.83kΩ
Ω)
120
1200
100
1000
80
800
ICH (mA)
VBAT = 3.3V
60
40
20
VBAT = 3.9V
VBAT = 3.5V
600
400
200
0
0
2.5
3
3.5
4
4
4.5
4.25
4.5
4.75
Battery Voltage (V)
5
5.25
5.5
5.75
6
Supply Voltage (V)
Fast Charge Current vs. Supply Voltage
Fast Charge Current vs. Supply Voltage
(SETL; SETL = 40.2kΩ
Ω)
(SETH; SETH = 3.83kΩ
Ω)
1200
120
0°C
VBAT = 3.5V
1000
100
VBAT = 3.9V
70°C
800
60
ICH (mA)
80
ICH (mA)
4
Battery Voltage (V)
Temperature (°C)
ICH (mA)
3.5
VBAT = 3.3V
40
20
25°C
600
400
200
0
4
4.5
5
5.5
Supply Voltage (V)
3685.2006.10.1.3
6
6.5
0
4.40
4.50
4.60
4.70
4.80
4.90
5.00
Supply Voltage (V)
7
AAT3685
Lithium-Ion/Polymer Battery Charger
Typical Characteristics
VIH vs. Supply Voltage
VIL vs. Supply Voltage
EN Pin (Rising)
EN Pin (Falling)
1.4
1.4
1.3
1.3
1.2
1.2
-40°C
+25°C
1.1
1.0
VIL (V)
VIH (V)
1.1
0.9
0.8
0.7
-40°C
0.9
0.8
0.7
+85°C
0.6
0.6
0.5
+85°C
0.5
0.4
0.4
4.2
4.4
4.6
4.8
5
5.2
5.4
5.6
5.8
6
4.2
4.4
4.6
Supply Voltage (V)
5.2
5.4
5.6
5.8
6
5.8
6
PWRSEL (Falling)
1.4
1.4
1.3
1.3
1.2
-40°C
1.1
1.2
+25°C
0.9
0.8
0.7
+25°C
1.0
0.9
0.8
0.7
+85°C
0.6
-40°C
1.1
1.0
VIL (V)
VIH (V)
5
VIL vs. Supply Voltage
PWRSEL (Rising)
+85°C
0.6
0.5
0.5
0.4
0.4
4.2
4.4
4.6
4.8
5
5.2
5.4
5.6
5.8
6
4.2
4.4
4.6
Supply Voltage (V)
4.8
5
5.2
5.4
5.6
Supply Voltage (V)
Supply Current vs. SETH Resistor
Charge Current vs. Time
(SETH; SETH = 3.83kΩ
Ω)
0.80
VBUS
(400mV/div)
0.70
Constant Current
0.50
Charge Reduction
Mode Activated
Charge
Current
(400mA/div)
0.60
IQ (mA)
4.8
Supply Voltage (V)
VIH vs. Supply Voltage
0.40
0.30
Peripheral
Current
Consumption
(400mA/div)
Pre-Conditioning
0.20
0.10
0.00
1
10
100
SETH Resistor (kΩ
Ω)
8
+25°C
1.0
1000
0
1
2
3
4
5
6
7
8
9
10
Time (sec)
3685.2006.10.1.3
AAT3685
Lithium-Ion/Polymer Battery Charger
Typical Characteristics
Temperature Sense Output
Current vs. Temperature
TS Pin CUrrent (μA)
88
86
84
82
80
78
76
74
72
-50
-25
0
25
50
75
100
Temperature (°°C)
3685.2006.10.1.3
9
AAT3685
Lithium-Ion/Polymer Battery Charger
Functional Block Diagram
Reverse Blocking
ADP/USB
PWRSEL
SETH
SETL
CHR
BAT
Current
Compare
Charge
Reduction
Loop
CV/
Precharge
Charge
Control
Constant
Current
UVLO
OverTemperature
Protect
STAT1
STAT2
Charge
Status
80μA
DATA
TS
Serial
Data
Window
Comparator
IC enable
EN
GND
Functional Description
The AAT3685 is a highly integrated single cell lithium-ion/polymer battery charger IC designed to
operate from adapter or USB port VBUS supplies,
while requiring a minimum number of external
components. The device precisely regulates battery charge voltage and current for 4.2V lithiumion/polymer battery cells.
The AAT3685 is specifically designed for being
powered from a USB port VBUS supply, but it can
also be powered from any input voltage source
capable supplying 4.5V to 5.5V for loads up to 1A.
The AAT3685 constant charge current can be
externally programmed for two levels, SETH and
SETL, for maximum constant current charge levels
up to 1A. The SETH/L mode has an automatic
Charge Reduction Loop control to allow users to
charge the battery with limited available current
from a port while maintaining the regulated port
voltage. This system assures the battery charge
10
function will not overload the port while charging if
other system demands also share power with the
respective port supply.
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 14 various charge states to a system
microcontroller.
Battery temperature and charge state are fully
monitored for fault conditions. In the event of an
over-voltage or over-temperature failure, the
device will automatically shut down, thus protecting
the charging device, control system, and the battery under charge. In addition to internal charge
controller thermal protection, the AAT3685 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.
3685.2006.10.1.3
AAT3685
Lithium-Ion/Polymer Battery Charger
Charge Complete Voltage
Preconditioning
Trickle Charge
Phase
Constant Current
Charge Phase
Constant Voltage
Charge Phase
I = Max CC
Regulated Current
Constant Current Mode
Voltage Threshold
Trickle Charge and
Termination Threshold
I = CC / 10
Figure 1: Current vs. Voltage Profile During Charging Phases.
Charging Operation
The AAT3685 has four basic modes for the battery
charge cycle and is powered from the input: pre-conditioning/trickle charge; constant current/fast charge;
constant voltage; and end of charge. For reference,
Figure 1 shows the current versus voltage profile
during charging phases.
Battery Preconditioning
Before the start of charging, the AAT3685 checks
several conditions in order to assure a safe charging
environment. The input supply must be above the
minimum operating voltage, or under-voltage lockout
threshold (VUVLO), for the charging sequence to
begin. In addition, the cell temperature, as reported
by a thermistor connected to the TS pin from the battery, must be within the proper window for safe
charging. When these conditions have been met and
a battery is connected to the BAT pin, the AAT3685
checks the state of the battery. If the cell voltage is
below the Preconditioning Voltage Threshold (VMIN),
the AAT3685 begins preconditioning the cell.
The battery preconditioning trickle charge current
is equal to the fast charge constant current divided
by 10. For example, if the programmed fast charge
current is 500mA, then the preconditioning mode
(trickle charge) current will be 50mA. Cell preconditioning is a safety precaution for a deeply discharged battery and also aids in limiting power dissipation in the pass transistor when the voltage
across the device is at the greatest potential.
Fast Charge / Constant Current Charging
Battery cell preconditioning continues until the voltage on the BAT pin exceeds the Preconditioning
Voltage Threshold (VMIN). At this point, the AAT3685
begins the constant current fast charging phase.
3685.2006.10.1.3
The fast charge constant current (ICC) amplitude is
determined by the selected charge mode SETH or
SETL and is programmed by the user via the RSETH
and RSETL resistors. The AAT3685 remains in constant current charge mode until the battery reaches
the voltage regulation point, VBAT.
Constant Voltage Charging
The system transitions to a constant voltage charging mode when the battery voltage reaches output
charge regulation threshold (VBAT) during the constant current, fast charge phase. The regulation
voltage level is factory programmed to 4.2V ( 1%).
The charge current in the constant voltage mode
drops as the battery cell under charge reaches its
maximum capacity.
End of Charge Cycle Termination and Recharge
Sequence
When the charge current drops to 7.5% of the programmed fast charge current level in the constant voltage mode, the device terminates charging and goes
into a sleep state. The charger will remain in a sleep
state until the battery voltage decreases to a level
below the battery recharge voltage threshold (VRCH).
When the input supply is disconnected, the charger will also automatically enter power-saving sleep
mode. Only consuming an ultra-low 0.3μA in sleep
mode (1μA for AAT3685-1), the AAT3685 minimizes battery drain when it is not charging. This
feature is particularly useful in applications where
the input supply level may fall below the battery
charge or under-voltage lockout level. In such
cases where the AAT3685 input voltage drops, the
device will enter the sleep mode and automatically
resume charging once the input supply has recovered from its fault condition.
11
AAT3685
Lithium-Ion/Polymer Battery Charger
System Operation Flow Chart
Switch
On
Sleep
Mode
No
UVLO
VP > VUVLO
Power On
Reset
Fault
Conditions Monitor
OV, OT
Battery
Temperature Monitor
SETL
Current Loop
0
SETH
Current Loop
1
No
Battery
Temp. Fault
No
Yes
Preconditioning Test
VMIN > VBAT
Yes
Low Current
Conditioning
Charge
Input Voltage
Regulation
Enable
No
Port
Voltage Test
VADP/USB < VADP/USB_CHR
Yes
No
Current Phase Test
VEOC > VBAT
Input Detect
PWRSEL= ?
Shut Down
Mode
VTS1 < TS < VTS2
Recharge Test
VRCH > VBAT
Input Power
Yes
No
Yes
Yes
Yes
Current
Charging
Mode
Yes
Voltage
Charging
Mode
Charge
Current
Reduction
No
Voltage Phase Test
IBAT > ITERM
No
Charge
Completed
12
3685.2006.10.1.3
AAT3685
Lithium-Ion/Polymer Battery Charger
Application Information
fast charge current to maintain port integrity and
protect the host system.
USB System Power Charging
The charge reduction system becomes active when
the voltage on the input falls below the charge
reduction threshold (VADP/USB_CHR), which is typically 4.5V. Regardless of which charge function is
selected (SETH or SETL), the charge reduction
system will reduce the fast charge current level in a
linear fashion until the voltage sensed on the input
recovers above the charge reduction threshold voltage. The charge reduction threshold (VADP/USB_CHR)
may be externally set to a value lower than 4.5V by
placing a resistor divider network between VADP/USB
and ground with the center connected to the CHR
pin. The charge reduction feature may be disabled
by connecting a 10kΩ resistor from the CHR pin
directly to the ADP/USB input pin.
The USB charge mode provides two programmable fast charge levels up to 1A for each, SETH and
SETL. The SETH or SETL modes may be externally selected by the select pin (PWRSEL). When
the PWRSEL pin is connected to a logic high level,
the SETH level will be active. Conversely, when
PWRSEL is pulled to a logic low level (ground), the
SETL level will be used for fast charging. These
two charge levels may be user programmed to any
level between 50mA and 1A by selecting the appropriate resistor values for RSETH and RSETL. Refer to
Table 1 for recommended RSETH and RSETL values
for the desired input constant current charge levels.
Charge Reduction
In many instances, product system designers do
not know the real properties of a potential port to be
used to supply power to the battery charger.
Typical powered USB ports commonly found on
desktop and notebook PCs should supply up to
500mA. In the event a port being used to supply
the charger is unable to provide the programmed
fast charge current, or if the system under charge
must also share supply current with other functions, the AAT3685 will automatically reduce USB
The following equation may be used to approximate
a USB charge reduction threshold below 4.5V:
R12
Eq. 1: VADP/USB_CHR = 2.0V ÷ R12 + R11
where R11/R12 << 1MΩ.
VADP/USB
ICC
SETH
SETL
Ω) RSET (kΩ
Ω)
RSET (kΩ
50
75
100
200
300
400
86.6
57.6
42.2
21.0
13.7
10.2
86.6
57.6
42.2
20.5
13.7
10.2
ICC
SETH
Ω)
RSET (kΩ
SETL
Ω)
RSET (kΩ
500
600
700
800
900
1000
8.06
6.65
5.62
4.87
4.32
3.83
8.06
6.65
5.62
4.87
4.32
3.83
R11
1.025M
CHR
R12
ADP/USB
VCHR = 2.0V
825k
Table 1: Recommended RSET Values.
Figure 2: Internal Equivalent
Circuit for the CHR Pin.
3685.2006.10.1.3
13
AAT3685
Lithium-Ion/Polymer Battery Charger
Input Charge Inhibit and Resume
The AAT3685 UVLO and power on reset feature
will function when the input pin voltage level drops
below the UVLO threshold. At this point, the charger will suspend charging and shut down. When
power is re-applied to the ADP/USB pin or the
UVLO condition recovers, the system charge control will assess the state of charge on the battery
cell and will automatically resume charging in the
appropriate mode for the condition of the battery.
Single Path Charging from a Line Adapter or
USB Source
Most USB charging applications limit charging current to 500mA due to the limitations of a USB port
as a power source. The AAT3685 is capable of,
and may be programmed for, constant current
charge levels up to 1A. Thus, charging operation
is not just restricted to use with USB port supplies.
Any power source may be used within the operating voltage limits as specified in the Electrical
Characteristics section of this datasheet. This
makes the AAT3685 perfect for applications that
only have one input path, but may access either a
line adapter source or a USB port supply.
In order to fully utilize the power capacity from a line
adapter or USB port supply, program the SETH
charge rate according to the highest charging current capacity of the two possible sources, providing
that neither supply exceeds 1A. A lower charge
level may be set with the SETL charge rate and
selection of the higher or lower charge rate is controlled via the PWRSEL function. If the programmed charge rate is greater than the current
source capacity, there is little danger of system failure because the AAT3685 charge reduction loop
will activate to automatically reduce the charging
current and maintain a supply voltage set by the
CHR threshold. If the input supply is incapable of
maintaining an input voltage greater than the undervoltage lockout level of the AAT3685, the charge
control will suspend charging until the source supply is capable of supplying the minimum input current to charge. At this point, the AAT3685 will auto-
14
matically resume charging in the appropriate mode
based on the battery cell voltage. In case of an
over-temperature condition with a high charge current and large input-to-battery voltage difference,
the device will cycle from charging to thermal shutdown and re-charge after temperature drops sufficiently, until the battery is charged to 4.2V.
Enable / Disable
The AAT3685 provides an enable function to control the charger IC on and off. The enable (EN) pin
is an active high. When pulled to a logic low level,
the AAT3685 will be shut down and forced into the
sleep state. Charging will be halted regardless of
the battery voltage or charging state. When the
device is re-enabled, the charge control circuit will
automatically reset and resume charging functions
with the appropriate charging mode based on the
battery charge state and measured cell voltage.
Programming Charge Current
The fast charge constant current charge level for the
ADP/USB input is programmed with set resistors
placed between the SETH and SETL pins and
ground. The accuracy of the fast charge, as well as
the preconditioning trickle charge current, is dominated by the tolerance of the set resistors used. For
this reason, 1% tolerance metal film resistors are
recommended for programming the desired constant current level.
The fast charge constant current charge control
provides for two current set levels, SETH and
SETL. The PWRSEL pin is used to select the high
or low charge current levels. When the PWRSEL
pin is pulled to a voltage level above the VPWRSEL(H)
threshold, the SETH current level will be selected.
Conversely, this pin should be pulled below the
VPWRSEL(L) to enable the SETL charge level. These
two charge levels may be set to any level between
50mA and 1A, depending upon the system design
requirements for a given charge application. Refer
to Table 1 and Figure 3 for recommended RSETH
and RSETL values.
3685.2006.10.1.3
AAT3685
Lithium-Ion/Polymer Battery Charger
IFASTCHARGE (mA)
10000
1000
SETL
100
10
SETH
1
10
100
1000
RSET (kΩ)
Figure 3: IFASTCHARGE vs. RSET.
Protection Circuitry
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
over-voltage protection threshold (VOVP). If an
over-voltage condition occurs, the AAT3685 charge
control will shut down the device until voltage on
the BAT pin drops below the over-voltage protection threshold (VOVP). The AAT3685 will resume
normal charging operation after the over-voltage
condition is removed. During an over-voltage
event, the STAT LEDs will report a system fault; the
actual fault condition may also be read via the
DATA pin signal.
Over-Temperature Shutdown
The AAT3685 has a thermal protection control circuit which will shut down charging functions should
the internal die temperature exceed the preset
thermal limit threshold.
Battery Temperature Fault Monitoring
In the event of a battery over-temperature condition, the charge control will turn off the internal pass
device and report a battery temperature fault on the
DATA pin function. The STAT LEDs will also display a system fault. After the system recovers
from a temperature fault, the device will resume
charging operation.
3685.2006.10.1.3
The AAT3685 checks battery temperature before
starting the charge cycle, as well as during all stages
of charging. This is accomplished by monitoring the
voltage at the TS pin. This system is intended for
use negative temperature coefficient (NTC) thermistors which are typically integrated into the battery
package. Most commonly used NTC thermistors
used in battery packs are approximately 10kΩ at
room temperature (25°C). The TS pin has been
specifically designed to source 80μA of current to
the thermistor. The voltage on the TS pin that results
from the resistive load should stay within a window
from 335mV to 2.32V. If the battery becomes too hot
during charging due to an internal fault, the thermistor will heat up and reduce in value, thus pulling the
TS pin voltage lower than the TS1 threshold, and the
AAT3685 will halt charging and signal the fault condition. If the use of the TS pin function is not
required by the system, it should be terminated to
ground using a 10kΩ resistor. Alternatively, on the
AAT3685-1, the TS pin may be left open.
Battery Charge Status Indication
The AAT3685 indicates the status of the battery
under charge with two different systems. First, the
device has two status LED driver outputs. These
two LEDs can indicate simple functions such as no
battery charge activity, battery charging, charge
complete, and charge fault. The AAT3685 also
provides a bi-directional data reporting function so
that a system microcontroller may interrogate the
DATA pin and read any one of 14 system states.
Status Indicator Display
Simple system charging status may be displayed
using one or two LEDs in conjunction with the
STAT1 and STAT2 pins on the AAT3685. These
two pins are simple switches to connect the display
LED cathodes to ground. It is not necessary to use
both display LEDs if a user simply wants to have a
single lamp to show "charging" or "not charging."
This can be accomplished by just using the STAT1
pin and a single LED. Using two LEDs and both
STAT pins simply gives the user more information
for charging states. Refer to Table 2 for LED display definitions.
15
AAT3685
Lithium-Ion/Polymer Battery Charger
Event Description
Charge Disabled or Low Supply
Charge Enabled Without Battery
Battery Charging
Charge Completed
Fault
STAT1
STAT2
Off
Flash1
On
Off
On
Off
Flash1
Off
On
On
Table 2: LED Display Status Conditions.
The LED anodes should be connected to VADP/USB.
The LEDs should be biased with as little current as
necessary to create reasonable illumination; therefore, a ballast resistor should be placed between
each of the LED cathodes and the STAT1/2 pins.
LED current consumption will add to the over-thermal power budget for the device package, hence it
is recommended to keep the LED drive current to a
minimum. 2mA should be sufficient to drive most
low-cost green, red, or multi-color LEDs. It is not
recommended to exceed 8mA for driving an individual status LED.
The required ballast resistor value can be estimated using the following formulas:
Eq. 2: RB(STAT1/2) =
(VAPD/USB - VF(LED))
ILED(STAT1/2)
Example:
RB(STAT1) =
(5.0V - 2.0V)
= 1.5kΩ
2mA
Note: Red LED forward voltage (VF) is typically
2.0V @ 2mA.
Table 2 shows the four status LED display conditions.
Digital Charge Status Reporting
The AAT3685 has a comprehensive digital data
reporting system by use of the DATA pin feature.
This function can provide detailed information
regarding the state of the charging system. The
DATA pin is a bi-directional port which will read
back a series of data pulses when the system
microcontroller asserts a request pulse. This single strobe request protocol will invoke one of 14
possible return pulse counts in which the microcontroller can look up based on the serial report
shown in Table 3.
The DATA pin function is active low and should normally be pulled high to VADP/USB. This data line
may also be pulled high to the same level as the
high state for the logic I/O port on the system
microcontroller. In order for the DATA pin control
circuit to generate clean sharp edges for the data
output and to maintain the integrity of the data timing for the system, the pull-up resistor on the data
line should be low enough in value so that the
DATA signal returns to the high state without delay.
If the value of the pull-up resistor used is too high,
the strobe pulse from the system microcontroller
may exceed the maximum pulse time and the
DATA output control could issue false status
reports. A 1.5kΩ resistor is recommended when
pulling the DATA pin high to 5.0V at the VUSB input.
If the data line is pulled high to a voltage level less
than 5.0V, the pull-up resistor may be calculated
based on a recommended minimum pull-up current
of 3mA. Use the following formula:
Eq. 3: RPULL-UP ≤
VPULL-UP
3mA
1. Flashing rate depends on output capacitance.
16
3685.2006.10.1.3
AAT3685
Lithium-Ion/Polymer Battery Charger
N
DATA Report Status
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
Chip Over-Temperature Shutdown
Battery Temperature Fault
Over-Voltage Turn Off
Not Used
Not Used
Not Used
Not Used
Not Used
Not Used
Not Used
Not Used
Not Used
SETH Battery Condition Mode
SETH Charge Reduction in Constant Current Mode
SETH Constant Current Mode
SETH Constant Voltage Mode
SETH End of Charging
SETL Battery Condition Mode
SETL Charge End of Charging Reduction in Constant Current Mode
SETL Constant Current Mode
SETL Constant Voltage Mode
SETL End of Charging
Data Report Error
Table 3: Serial Data Report Table.
1.8V to 5.0V
IN
AAT3685
Status
Control
RPULL_UP
IN
DATA Pin
GPIO
OUT
OUT
μP GPIO
Port
Figure 4: Data Pin Application Circuit.
3685.2006.10.1.3
17
AAT3685
Lithium-Ion/Polymer Battery Charger
Data Timing
the AAT3685 status data control will reply the data
word back to the system microcontroller after a
delay specified by the data report time specification
TDATA(RPT). The period of the following group of data
pulses will be specified by the TDATA specification.
The system microcontroller should assert an active
low data request pulse for minimum duration of
200ns; this is specified by TLO(DATA). Upon sensing
the rising edge of the end of the data request pulse,
Timing Diagram
SQ
SQPULSE
PDATA
System Reset
System Start
CK
TSYNC
Data
TLAT
TDATA(RPT) = TSYNC + TLAT < 2.5 PDATA
TOFF > 2 PDATA
TOFF
N=1
N=2
Thermal Considerations
Where:
The AAT3685 is packaged in a Pb-free, 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 design. The
ambient temperature around the charger IC will
also have an affect on the thermal limits of a battery charging application. The maximum limits that
can be expected for a given ambient condition can
be estimated by the following discussion.
PD
First, the maximum power dissipation for a given
situation should be calculated:
N=3
= Total Power Dissipation by the Device
VIN = Input Voltage Level, VADP/USB
VBAT = Battery Voltage as Seen at the BAT Pin
ICC
= Maximum Constant Fast Charge Current
Programmed for the Application
IOP
= Quiescent Current Consumed by the
Charger IC for Normal Operation
Next, the maximum operating ambient temperature
for a given application can be estimated based on
the thermal resistance of the 3x3mm TDFN package when sufficiently mounted to a PCB layout and
the internal thermal loop temperature threshold.
Eq. 5: TA = TJ - (θJA · PD)
Eq. 4: PD = [(VIN - VBAT) · ICC + (VIN · IOP)]
18
3685.2006.10.1.3
AAT3685
Lithium-Ion/Polymer Battery Charger
Where:
Capacitor Selection
TA
= Ambient Temperature in Degrees C
TJ
= Maximum Device Junction Temperature
Protected by the Thermal Limit Control
PD
= Total Power Dissipation by the Device
Input Capacitor
In general, it is good design practice to place a
decoupling capacitor between the ADP/USB pin
and ground. An input capacitor in the range of 1μF
to 22μF is recommended. If the source supply is
unregulated, it may be necessary to increase the
capacitance to keep the input voltage above the
under-voltage lockout threshold during device
enable and when battery charging is initiated.
θJA = Package Thermal Resistance in °C/W
Example:
For an application where the fast charge current is
set to 500mA, VUSB = 5.0V and the worst case battery voltage at 3.0V, what is the maximum ambient
temperature at which the thermal limiting will
become active?
Given:
VUSB = 5.0V
VBAT = 3.0V
ICC
= 500mA
IOP
= 0.75mA
TJ
= 140°C
θJA = 50°C/W
Using Equation 4, calculate the device power dissipation for the stated condition:
Eq. 6: PD = (5.0V - 3.0V)(500mA) + (5.0V · 0.75mA)
= 1.00375W
The maximum ambient temperature before the
AAT3685 thermal limit protection will shut down
charging can now be calculated using Equation 5:
Eq. 7: TA = 140°C - (50°C/W · 1.00375W)
= 89.81°C
Therefore, under the stated conditions for this
worst case power dissipation example, the
AAT3685 will suspend charging operations when
the ambient operating temperature rises above
89.81°C.
3685.2006.10.1.3
If the AAT3685 input is to be used in a system with
an external power supply source rather than a USB
port VBUS, such as a typical AC-to-DC wall adapter,
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. Likewise, a
10μF or greater input capacitor is recommended
for the USB input to help buffer the effects of USB
source power switching noise and input cable
impedance.
Output Capacitor
The AAT3685 only requires a 1μF ceramic capacitor on the BAT pin to maintain circuit stability. This
value should be increased to 10μF or more if the
battery connection is made any distance from the
charger output. If the AAT3685 is to be used in
applications where the battery can be removed
from the charger, such as in the case of desktop
charging cradles, an output capacitor greater than
10μF may be required to prevent the device from
cycling on and off when no battery is present.
Printed Circuit Board Layout
Considerations
For the best results, it is recommended to physically place the battery pack as close as possible
to the AAT3685 BAT pin. To minimize voltage
drops on the PCB, keep the high current carrying
traces adequately wide. For maximum power dissipation of the AAT3685 3x3mm TDFN package,
the metal substrate should be solder bonded to
the board. It is also recommended to maximize
the substrate contact to the PCB ground plane
layer to further increase local heat dissipation.
Refer to the AAT3685 evaluation board for a good
layout example (see Figures 5 and 6).
19
AAT3685
Lithium-Ion/Polymer Battery Charger
AAT3685 Evaluation Board Layout
Figure 5: AAT3685 Evaluation Board
Component Side Layout.
20
Figure 6: AAT3685 Evaluation Board
Solder Side Layout.
3685.2006.10.1.3
AAT3685
Lithium-Ion/Polymer Battery Charger
AAT3685 Evaluation Board Schematic Diagram
ON/OFF
J1
PWRSEL
J2
1 2 3
1 2 3
Mini-B
GND
ID
D+
DADP/USB
HI
LO
5
4
3
2
1
RED
GRN
LED D2 LED D1
C2
TB1
ADP/USB
10μF
1
2
GND
R2
R3
Open Open
U1
1
5
BAT
TS
GND
2
1
2
3
TB2
4
10μF
6
R4
10K
3685.2006.10.1.3
AAT3685
ADP/USB
EN
BAT
PWRSEL
STAT2
STAT1
DATA
C1
R1
Open
SETL
CHR
TS
R5
1.5K
SETH
GND
3
TDFN33-12
R6
1.5K
R9
1.5K
10
8
9
7
DATA
11
12
R8
R7
8.06K
40.2K
SW1
21
AAT3685
Lithium-Ion/Polymer Battery Charger
AAT3685 Evaluation Board Bill of Materials (BOM)
Quantity Description
1
1
1
1
2
1
1
2
1
3
1
1
1
1
22
Desig.
Test Pin
DATA
Connecting Terminal Block,
USB,GND
2.54mm, 2 Pos
Connecting Terminal Block, BAT, GND, TS
2.54mm, 3 Pos
USB 2.0 Receptacle, 5 Pos
USB
Footprint
Manufacturer
Part Number
PAD
TBLOK2
Mill-Max
Phoenix Contact
6821-0-0001-00-00-08-0
277-1274-ND
TBLOK3
Phoenix Contact
277-1273-ND
USB-MINI-B
Capacitor, Ceramic, 10μF
6.3V 10% X5R 0805
Typical Red LED, Super
Bright
Typical Green LED
C1, C2
0805
D1
1206LED
Header, 3-Pin
Resistor, 10kΩ 1/16W 5%
0603 SMD
Resistor, 1.5kΩ 1/16W
1% 0603 SMD
Resistor, 40.2kΩ 1/16W
1% 0603 SMD
Resistor, 8.06kΩ 1/16W
1% 0603 SMD
Switch Tact 6mm SPST
H = 5.0mm
AAT3685 Lithium-Ion/
Polymer Battery Charger
J1, J2
R4
D2
Hirose Electronic H2959CT-ND
Co. Ltd.
MuRata
490-1717-1-ND
Chicago Miniature
Lamp
1206LED
Chicago Miniature
Lamp
HEADER2MM-3 Sullins
0603
Panasonic/ECG
CMD15-21SRC/TR8
CMD15-21VGC/TR8
6821-0-0001-00-00-08-0
P10KCFCT-ND
R5, R6, R9
0603
Panasonic/ECG
P1.5KCGCT-ND
R7
0603
Panasonic/ECG
P40.2KHTR-ND
R8
0603
Panasonic/ECG
P8.06KHCT-ND
SW1
SWITCH
CKN9012-ND
U1
TDFN33-12
ITT Industries/
C&K Div.
AnalogicTech
AAT3685IWP
3685.2006.10.1.3
AAT3685
Lithium-Ion/Polymer Battery Charger
Ordering Information
Package
Marking1
Part Number (Tape and Reel)2
TDFN33-12
TDFN33-12
RNXYY
TMXYY
AAT3685IWP-4.2-T1
AAT3685IWP-4.2-1-T1
All AnalogicTech products are offered in Pb-free packaging. The term “Pb-free” means
semiconductor products that are in compliance with current RoHS standards, including
the requirement that lead not exceed 0.1% by weight in homogeneous materials. For more
information, please visit our website at http://www.analogictech.com/pbfree.
Package Information
2.40 ± 0.05
Detail "B"
3.00 ± 0.05
Index Area
(D/2 x E/2)
0.3 ± 0.10 0.16 0.375 ± 0.125
0.075 ± 0.075
3.00 ± 0.05
1.70 ± 0.05
Top View
Bottom View
Pin 1 Indicator
(optional)
0.23 ± 0.05
Detail "A"
0.45 ± 0.05
0.1 REF
0.05 ± 0.05
0.229 ± 0.051
+ 0.05
0.8 -0.20
7.5° ± 7.5°
Option A:
C0.30 (4x) max
Chamfered corner
Side View
Option B:
R0.30 (4x) max
Round corner
Detail "B"
Detail "A"
All dimensions in millimeters.
1. XYY = assembly and date code.
2. Sample stock is generally held on part numbers listed in BOLD.
© Advanced Analogic Technologies, Inc.
AnalogicTech cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in an AnalogicTech product. No circuit patent licenses, copyrights, mask work rights,
or other intellectual property rights are implied. AnalogicTech reserves the right to make changes to their products or specifications or to discontinue any product or service without notice.
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3685.2006.10.1.3
23