Analogic AAT3688 Usb port lithium-ion/polymer battery charger Datasheet

PRODUCT DATASHEET
AAT3688
BatteryManagerTM
USB Port Lithium-Ion/Polymer Battery Charger
General Description
Features
The AAT3688 BatteryManager™ is a highly integrated
single cell lithium-ion/polymer battery charger IC
designed to operate with USB port inputs. It requires the
minimum number of external components.
• USB Charger
▪ Programmable up to 500mA 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 for USB Charging
• 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
The AAT3688 precisely regulates battery charge voltage
and current for 4.2V lithium-ion/polymer battery cells.
Depending on the USB port type, the AAT3688 charge
current can be programmed for two separate levels up
to 500mA. An optional Charge Reduction Loop is built in
to allow users to charge the battery with available current from a USB port, 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.
Applications
•
•
•
•
•
•
•
The AAT3688 is available in a Pb-free, thermally-enhanced,
space-saving 12-pin 3x3mm TDFN package and is rated
over the -40°C to +85°C temperature range.
Bluetooth™ Headsets
Cellular Telephones
Digital Still Cameras
Hand-Held PCs
MP3 Players
Personal Data Assistants (PDAs)
Other Lithium-Ion/Polymer Battery-Powered Devices
Typical Application
Enable
USB Input
USB
EN
CHR
USBSEL
USB Hi/Lo Select
RSETH
RSETL
BATT+
USBH
BAT
USBL
TS
AAT3688
C2
10µF
BATT-
GND
DATA
STAT1
TEMP
STAT2
Battery Pack
Serial Data
3688.2007.12.1.6
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1
PRODUCT DATASHEET
AAT3688
BatteryManagerTM
USB Port Lithium-Ion/Polymer Battery Charger
Pin Descriptions
Pin #
Name
Type
1
2
3
USB
BAT
GND
In
In/Out
Ground
4
CHR
In/Out
5
6
7
8
9
10
11
12
EP
EN
TS
DATA
STAT2
STAT1
USBSEL
USBL
USBH
In
In/Out
In/Out
Out
Out
In
In/Out
In/Out
Function
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 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 USB is present, use this pin to toggle between USBH and USBL charging levels.
Connect resistor here to set charge current for low-current USB port.
Connect resistor here to set charge current for high-current USB port.
Exposed paddle (bottom); connect to GND directly beneath package.
Pin Configuration
TDFN33-12
(Top View)
2
USB
1
12
USBH
BAT
2
11
USBL
GND
3
10
USBSEL
CHR
4
9
STAT1
EN
5
8
STAT2
TS
6
7
DATA
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3688.2007.12.1.6
PRODUCT DATASHEET
AAT3688
BatteryManagerTM
USB Port Lithium-Ion/Polymer Battery Charger
Absolute Maximum Ratings1
Symbol
VP
VP
VN
TJ
TLEAD
Description
USB Input Voltage, <30ms, Duty Cycle <10%
USB Input Voltage, Continuous
BAT, USBSEL, USBH, USBL, 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 VVP + 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.
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PRODUCT DATASHEET
AAT3688
BatteryManagerTM
USB Port Lithium-Ion/Polymer Battery Charger
Electrical Characteristics1
VADP = 5V, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = 25°C.
Symbol
Description
Conditions
Operation
USB
Input Voltage Range
Under-Voltage Lockout
VUVLO
Under-Voltage Lockout Hysteresis
IOP
Operating Current
ISLEEP
Sleep Mode Current
Reverse Leakage Current from BAT Pin
ILeakage
Voltage Regulation
VBAT_EOC1
End of Charge Voltage Accuracy
ΔVBAT/VBAT
EOC Voltage Tolerance
VMIN
Preconditioning Voltage Threshold
VRCH
Min
4.0
Rising Edge
3.0
150
0.75
0.3
1.0
CC Charge Current = 500mA
VBAT = 4.25V
VBAT = 4V, USB Pin Open
4.158
2.8
4.2
0.5
3.0
4.3
1.9
VBAT_EOC 0.1
4.5
2.0
Battery Recharge Voltage Threshold
VUSB_CHR
USB Charge Reduction Regulation
VCHR
CHR Pin Voltage Accuracy
Current Regulation
ICH
Charge Current
ΔICH/ICH
Charge Current Regulation Tolerance
USBH Pin Voltage
VUSBH
VUSBL
USBL Pin Voltage
KIUH
Current Set Factor: ICHARGE/IUSBH
KIUL
Current Set Factor: ICHARGE/IUSBL
Charging Devices
RDS(ON)U
USB Charging Transistor On Resistance
Typ
No Connection on CHR Pin
50
Units
5.5
V
V
mV
mA
μA
μA
1.5
1.0
4.242
3.15
0.4
0.5
V
%
V
V
4.64
2.1
V
V
500
mA
%
V
V
0.65
Ω
10
2.0
2.0
2000
2000
CC Mode
CC Mode
VIN = 5.5V
Max
1. The AAT3688 output charge voltage is specified over the 0° to 70°C ambient temperature range; operation over the -40°C to +85°C temperature range is guaranteed by
design.
4
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3688.2007.12.1.6
PRODUCT DATASHEET
AAT3688
BatteryManagerTM
USB Port Lithium-Ion/Polymer Battery Charger
Electrical Characteristics1
VADP = 5V, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = 25°C.
Symbol
Description
Conditions
Logic Control / Protection
VUSBSEL(H)
Input High Threshold
VUSBSEL(L)
Input Low Threshold
VEN(H)
Input High Threshold
VEN(L)
Input Low Threshold
VSTAT
Output Low Voltage
STAT Pin Current Sink Capability
ISTAT
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
Min
Typ
Max
1.6
0.4
1.6
0.4
0.4
STAT Pin Sinks 4mA
For
For
For
For
USBH Mode
USBL Mode
USBH Mode
USBL 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
V
mA
V
%
0.4
Status Request
Units
%
%
μA
mV
V
mV
mA
V
V
ns
μs
kHz
°C
1. The AAT3688 output charge voltage is specified over the 0° to 70°C ambient temperature range; operation over the -40°C to +85°C temperature range is guaranteed by
design.
3688.2007.12.1.6
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PRODUCT DATASHEET
AAT3688
BatteryManagerTM
USB Port Lithium-Ion/Polymer Battery Charger
Typical Characteristics
IFASTCHARGE vs. RSET
Battery Voltage vs. Supply Voltage
4.242
4.221
VBAT (V)
IFASTCHARGE (mA)
1000
USBL
100
USBH
10
1
4.200
4.179
10
100
4.158
1000
4.5
4.75
RSET (kΩ)
5
5.25
5.5
Supply Voltage (V)
Recharge Voltage vs. Temperature
End of Charge Voltage vs. Temperature
4.242
4.140
4.130
4.120
4.221
VBAT (V)
VRCH (V)
4.110
4.100
4.090
4.080
4.070
4.200
4.179
4.060
4.050
4.040
4.158
-50
-25
0
25
50
75
100
-50
-25
Temperature (°°C)
0
25
50
75
100
Temperature (°°C)
Preconditioning Threshold
Voltage vs. Temperature
Preconditioning Charge Current vs. Temperature
(USBH; USBH = 8.06kΩ
Ω)
60
3.05
3.04
3.03
55
ICH (mA)
VMIN (V)
3.02
3.01
3.00
2.99
2.98
50
45
2.97
2.96
40
2.95
-50
-25
0
25
50
75
100
Temperature (°°C)
6
-50
-25
0
25
50
75
100
Temperature (°C)
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3688.2007.12.1.6
PRODUCT DATASHEET
AAT3688
BatteryManagerTM
USB Port Lithium-Ion/Polymer Battery Charger
Typical Characteristics
Fast Charge Current vs. Temperature
Charging Current vs. Battery Voltage
(USBH; USBH = 8.06kΩ
Ω)
(USBH; USBH = 8.06kΩ
Ω)
540
600
530
500
520
400
500
ICH (A)
ICH (mA)
510
490
480
300
200
470
460
100
450
440
0
-50
-25
0
25
50
75
100
2.5
3
3.5
Temperature (°C)
4
4.5
Battery Voltage (V)
Charging Current vs. Battery Voltage
Fast Charge Current vs. Supply Voltage
(USBL; USBL = 40.2kΩ
Ω)
(USBH; USBH = 8.06kΩ
Ω)
120
600
100
500
80
400
VBAT = 3.5V
ICH (mA)
ICH (mA)
VBAT = 3.3V
60
40
VBAT = 3.9V
300
200
100
20
0
0
2.5
3
3.5
4
4.5
4
4.25
Battery Voltage (V)
4.5
4.75
Fast Charge Current vs. Supply Voltage
5.25
5.5
5.75
6
Fast Charge Current vs. Supply Voltage
(USBL; USBL = 40.2kΩ
Ω)
(USBH; USBH = 8.06kΩ
Ω)
120
600
VBAT = 3.5V
0°C
100
500
VBAT = 3.9V
80
60
ICH (mA)
ICH (mA)
5
Supply Voltage (V)
VBAT = 3.3V
40
20
70°C
400
25°C
300
200
100
0
4
4.5
5
5.5
6
6.5
Supply Voltage (V)
3688.2007.12.1.6
0
4.40
4.50
4.60
4.70
4.80
4.90
5.00
Supply Voltage (V)
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PRODUCT DATASHEET
AAT3688
BatteryManagerTM
USB Port 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
4.8
Supply Voltage (V)
1.4
1.3
1.3
-40°C
VIL (V)
VIH (V)
-40°C
1.1
0.9
0.8
6
5.8
6
+25°C
1.0
0.9
0.8
+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
4.8
Supply Voltage (V)
5
5.2
5.4
5.6
Supply Voltage (V)
USB Charge Current vs. Time
USB Supply Current vs. USBH Resistor
0.80
(USBH; USBH = 8.06kΩ
Ω)
USB VBUS
(200mV/div)
0.70
USB Charge
Current
(200mA/div)
0.60
IQ (mA)
5.8
0.7
+85°C
0.6
5.6
1.2
+25°C
1.0
0.7
5.4
USBSEL (Falling)
1.4
1.1
5.2
VIL vs. Supply Voltage
USBSEL (Rising)
1.2
5
Supply Voltage (V)
VIH vs. Supply Voltage
Constant Current
0.50
Charge Reduction
Mode Activated
0.40
0.30
USB Peripheral
Current
Consumption
(200mA/div)
Pre-Conditioning
0.20
0.10
0.00
0
1
10
100
2
4
6
8
10
1000
USBH Resistor (kΩ
Ω)
8
+25°C
1.0
Time (sec)
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PRODUCT DATASHEET
AAT3688
BatteryManagerTM
USB Port 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)
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PRODUCT DATASHEET
AAT3688
BatteryManagerTM
USB Port Lithium-Ion/Polymer Battery Charger
Functional Block Diagram
Reverse Blocking
USB
USBSEL
USBH
USBL
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 AAT3688 is a highly integrated single cell lithiumion/polymer battery charger IC designed to operate from
USB port VBUS supplies, while requiring a minimum number of external components. The device precisely regulates battery charge voltage and current for 4.2V lithium-ion/polymer battery cells.
The AAT3688 is specifically designed to be 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 500mA. Depending on the USB port type,
the AAT3688 constant charge current can be externally
programmed for two levels, USB high and USB low, for
maximum constant current charge levels up to 500mA.
Typically, the USB charge levels are set at 500mA and
100mA for the USBH and USBL modes; however, the
user may program either mode to any level they desire
below 500mA. The USBH/L mode has an automatic
Charge Reduction Loop control to allow users to charge
the battery with limited available current from a USB
10
port while maintaining the regulated port voltage. This
system assures the battery charge function will not overload a USB 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
AAT3688 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.
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3688.2007.12.1.6
PRODUCT DATASHEET
AAT3688
BatteryManagerTM
USB Port Lithium-Ion/Polymer Battery Charger
Preconditioning
Trickle Charge
Phase
Constant Current
Charge Phase
Constant Voltage
Charge Phase
Charge Complete Voltage
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 AAT3688 has four basic modes for the battery
charge cycle and is powered from the USB input: preconditioning/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 AAT3688 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 AAT3688 checks the state of the battery. If the
cell voltage is below the Preconditioning Voltage Threshold
(VMIN), the AAT3688 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 AAT3688 begins the
3688.2007.12.1.6
constant current fast charging phase. The fast charge
constant current (ICC) amplitude is determined by the
selected charge mode USBH or USBL and is programmed
by the user via the RSETH and RSETL resistors. The
AAT3688 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, the
AAT3688 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 AAT3688 input voltage drops, the device will
enter the sleep mode and automatically resume charging once the input supply has recovered from its fault
condition.
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PRODUCT DATASHEET
AAT3688
BatteryManagerTM
USB Port Lithium-Ion/Polymer Battery Charger
System Operation Flow Chart
Switch
On
Sleep
Mode
No
UVLO
VP > VUVLO
Yes
USB Low
Current Loop
USB
Power
0
Power On
Reset
USB High
Current Loop
Fault Conditions
Monitor
OV, OT
Battery
1
Yes
No
Yes
USB Detect
USBSEL= ?
Shut Down
Mode
No
Temperature Monitor
VTS1 < TS < VTS2
Battery
Temp. Fault
USB Voltage
Regulation
Enable
No
No
Yes
Yes
Recharge Test
VRCH > VBAT
Preconditioning Test
VMIN > VBAT
Low Current
Conditioning
Charge
USB Voltage Test
VUSB < 4.5V
Yes
No
Yes
Current
Charging
Mode
Yes
Voltage
Charging
Mode
Current Phase Test
VEOC > VBAT
USB
Loop Current
Reduction in USB
Charging Mode
No
Voltage Phase Test
IBAT > ITERM
No
Charge
Completed
12
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3688.2007.12.1.6
PRODUCT DATASHEET
AAT3688
BatteryManagerTM
USB Port Lithium-Ion/Polymer Battery Charger
Application Information
Eq. 1: VUSBCHR = 2.0V ÷
USB System Power Charging
R12
R12 + R11
where R11/R12 << 1MΩ.
The USB charge mode provides two programmable fast
charge levels up to 500mA for each, USB high and USB
low, USBH and USBL, respectively. The USBH or USBL
modes may be externally selected by the USB select pin
(USBSEL). When the USBSEL pin is connected to a logic
high level, the USBH level will be active. Conversely,
when USBSEL is pulled to a logic low level (ground), the
USBL level will be used for fast charging. Typically USBH
is set for 500mA and USBL is set for 100mA. However,
these two USB charge levels may be user programmed
to any level between 50mA and 500mA by selecting the
appropriate resistor values for RSETH and RSETL. Refer to
Table 1 for recommended RSETH and RSETL values for the
desired USB input constant current charge levels.
ICC
USBH
RSET (kΩ)
USBL
RSET (kΩ)
50
75
100
200
300
400
500
86.6
57.6
42.2
21.0
13.7
10.2
8.06
86.6
57.6
42.2
20.5
13.7
10.2
8.06
Table 1: Recommended RSET Values.
VUSB
USB
USB Charge Reduction
In many instances, product system designers do not
know the real properties of a potential USB 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 USB 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 AAT3688 will automatically
reduce USB fast charge current to maintain port integrity and protect the host system.
The USB charge reduction system becomes active when
the voltage on the USB input falls below the USB charge
reduction threshold (VUSBCHR), which is typically 4.5V.
Regardless of which USB charge function is selected
(USBH or USBL), the charge reduction system will
reduce the fast charge current level in a linear fashion
until the voltage sensed on the USB input recovers
above the charge reduction threshold voltage. The USB
charge reduction threshold (VUSBCHR) may be externally
set to a value lower than 4.5V by placing a resistor
divider network between VUSB and ground with the center
connected to the CHR pin. The USB charge reduction
feature may be disabled by connecting a 10kΩ resistor
from the CHR pin directly to the USB input pin.
The following equation may be used to approximate a
USB charge reduction threshold below 4.5V:
3688.2007.12.1.6
R11
1.025M
CHR
VCHR = 2.0V
R12
825k
Figure 2: Internal Equivalent Circuit
for the CHR Pin.
USB Input Charge Inhibit and Resume
The AAT3688 UVLO and power on reset feature will function when the USB 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 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.
Enable / Disable
The AAT3688 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 AAT3688 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
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13
PRODUCT DATASHEET
AAT3688
BatteryManagerTM
USB Port Lithium-Ion/Polymer Battery Charger
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
USB input is programmed with set resistors placed
between the USBH and USBL 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 USB input fast charge constant current charge control
provides for two current set levels, USBH and USBL. The
USBSEL pin is used to select the high or low charge current levels in the USB charge mode. When the USBSEL
pin is pulled to a voltage level above the VUSBSEL(H) threshold, the USBH current level will be selected. Conversely,
this pin should be pulled below the VUSBSEL(L) to enable the
USBL charge level. Typically, the two RSETH and RSETL for
the USBH and USBL functions are fixed for 500mA and
100mA USB fast charge levels. However, these two
charge levels may be set to any level between 50mA and
500mA, depending upon the system design requirements
for a given USB charge application. Refer to Table 1 and
Figure 3 for recommended RSETH and RSETL values.
IFASTCHARGE (mA)
10000
1000
USBL
100
USBH
10
1
10
100
1000
RSET (kΩ
Ω)
Over-Temperature Shutdown
The AAT3688 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.
The AAT3688 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 AAT3688 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.
Battery Charge Status Indication
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
14
occurs, the AAT3688 charge control will shut down the
device until voltage on the BAT pin drops below the overvoltage protection threshold (VOVP). The AAT3688 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.
The AAT3688 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 AAT3688 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.
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3688.2007.12.1.6
PRODUCT DATASHEET
AAT3688
BatteryManagerTM
USB Port Lithium-Ion/Polymer Battery Charger
Status Indicator Display
Example:
Simple system charging status may be displayed using
one or two LEDs in conjunction with the STAT1 and
STAT2 pins on the AAT3688. 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.
Event Description
STAT1
STAT2
Charge Disabled or Low Supply
Charge Enabled Without Battery
Battery Charging
Charge Completed
Fault
Off
Flash1
On
Off
On
Off
Flash1
Off
On
On
Table 2: LED Display Status Conditions.
The LED anodes should be connected to VUSB. 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) =
(VUSB - VF(LED))
ILED(STAT1/2)
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 AAT3688 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 VUSB. 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.
3688.2007.12.1.6
www.analogictech.com
15
PRODUCT DATASHEET
AAT3688
BatteryManagerTM
USB Port Lithium-Ion/Polymer Battery Charger
Data Timing
N
DATA Report Status
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
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
USBH Battery Condition Mode
USBH Charge Reduction in Constant Current Mode
USBH Constant Current Mode
USBH Constant Voltage Mode
USBH End of Charging
USBL Battery Condition Mode
USBL Charge End of Charging Reduction in
Constant Current Mode
USBL Constant Current Mode
USBL Constant Voltage Mode
USBL End of Charging
Data Report Error
19
20
21
22
23
Table 3: Serial Data Report Table.
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, the AAT3688 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.
Thermal Considerations
The AAT3688 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.
1.8V to 5.0V
IN
AAT3688
Status
Control
RPULL_UP
IN
DATA Pin
GPIO
OUT
OUT
μP GPIO
Port
Figure 4: Data Pin Application Circuit.
16
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3688.2007.12.1.6
PRODUCT DATASHEET
AAT3688
BatteryManagerTM
USB Port Lithium-Ion/Polymer Battery Charger
Timing Diagram
SQPULSE
SQ
PDATA
System Reset
System Start
CK
TSYNC
Data
TLAT
TOFF
TDATA(RPT) = TSYNC + TLAT < 2.5 PDATA
TOFF > 2 PDATA
First, the maximum power dissipation for a given situation should be calculated:
Eq. 4: PD = [(VIN - VBAT) · ICC + (VIN · IOP)]
N=1
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?
Where:
Given:
PD
VIN
VBAT
ICC
VADP
VBAT
ICC
IOP
TJ
θJA
IOP
=
=
=
=
Total Power Dissipation by the Device
Input Voltage Level, VUSB
Battery Voltage as Seen at the BAT Pin
Maximum Constant Fast Charge Current
Programmed for the Application
= 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.
=
=
=
=
=
=
5.0V
3.0V
500mA
0.75mA
140°C
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 AAT3688
thermal limit protection will shut down charging can now
be calculated using Equation 5:
Eq. 5: TA = TJ - (θJA · PD)
Where:
TA = Ambient Temperature in Degrees C
TJ = Maximum Device Junction Temperature Protected
by the Thermal Limit Control
PD = Total Power Dissipation by the Device
θJA = Package Thermal Resistance in °C/W
3688.2007.12.1.6
N=3
N=2
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 AAT3688 will suspend charging operations when the ambient operating
temperature rises above 89.81°C.
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17
PRODUCT DATASHEET
AAT3688
BatteryManagerTM
USB Port Lithium-Ion/Polymer Battery Charger
Capacitor Selection
Output Capacitor
Input Capacitor
In general, it is good design practice to place a decoupling capacitor between the VUSB 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.
If the AAT3688 USB 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.
18
The AAT3688 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 AAT3688 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
AAT3688 BAT pin. To minimize voltage drops on the PCB,
keep the high current carrying traces adequately wide.
For maximum power dissipation of the AAT3688 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
AAT3688 evaluation board for a good layout example
(see Figures 5 and 6).
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3688.2007.12.1.6
PRODUCT DATASHEET
AAT3688
BatteryManagerTM
USB Port Lithium-Ion/Polymer Battery Charger
AAT3688 Evaluation Board Layout
Figure 5: AAT3688 Evaluation Board
Component Side Layout.
Figure 6: AAT3688 Evaluation Board
Solder Side Layout.
AAT3688 Evaluation Board Schematic Diagram
ON/OFF
USBSEL
J1
J2
1 2 3
1 2 3
Mini-B
HI
RED
GRN
LED D2 LED D1
C2
TB1
USB
GND
10μF
R9
1
2
R3
R2
Open Open
U1
1
5
BAT
TS
GND
2
1
2
3
AAT3688
USBSEL
USB
EN
STAT2
BAT
STAT1
DATA
TB2
4
C1
USBL
CHR
USBH
10μF
6
R4
10K
3688.2007.12.1.6
LO
5
4
3
2
1
GND
ID
D+
DVBUS
R1
Open
TS
10
R6
1.5K
1.5K
1.5K
8
9
7
DATA
11
12
GND
3
R5
TDFN33-12
www.analogictech.com
R8
R7
8.06K
42.2K
SW1
19
PRODUCT DATASHEET
AAT3688
BatteryManagerTM
USB Port Lithium-Ion/Polymer Battery Charger
AAT3688 Evaluation Board Bill of Materials (BOM)
Quantity
Description
Desig.
Footprint
Manufacturer
Part Number
1
Test Pin
Connecting Terminal Block,
2.54mm, 2 Pos
Connecting Terminal Block,
2.54mm, 3 Pos
DATA
USB,
GND
BAT,
GND, TS
PAD
Mill-Max
6821-0-0001-00-00-08-0
TBLOK2
Phoenix Contact
277-1274-ND
TBLOK3
Phoenix Contact
277-1273-ND
1
USB 2.0 Receptacle, 5 Pos
USB
USB-MINI-B
Hirose Electronic
Co. Ltd.
H2959CT-ND
2
Capacitor, Ceramic, 10μF 6.3V
10% X5R 0805
C1, C2
0805
Murata
490-1717-1-ND
1
Typical Red LED, Super Bright
D1
1206LED
1
Typical Green LED
D2
1206LED
2
Header, 3-Pin
Resistor, 10kΩ 1/16W 5% 0603
SMD
Resistor, 1.5kΩ 1/16W 1% 0603
SMD
Resistor, 42.2kΩ 1/16W 1% 0603
SMD
Resistor, 8.06kΩ 1/16W 1% 0603
SMD
J1, J2
1
1
1
3
1
1
20
HEADER2MM-3
Chicago Miniature
Lamp
Chicago Miniature
Lamp
Sullins
6821-0-0001-00-00-08-0
R4
0603
Panasonic/ECG
P10KCFCT-ND
R5, R6,
R9
0603
Panasonic/ECG
P1.5KHTR-ND
R7
0603
Panasonic/ECG
P42.2KHTR-ND
R8
0603
Panasonic/ECG
P8.06KHCT-ND
CMD15-21SRC/TR8
CMD15-21VGC/TR8
1
Switch Tact 6mm SPST H = 5.0mm
SW1
SWITCH
ITT Industries/
C&K Div.
CKN9012-ND
1
AAT3688 USB Port Lithium-Ion/
Polymer Battery Charger
U1
TDFN33-12
AnalogicTech
AAT3688IWP
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3688.2007.12.1.6
PRODUCT DATASHEET
AAT3688
BatteryManagerTM
USB Port Lithium-Ion/Polymer Battery Charger
Ordering Information
Package
Marking1
Part Number (Tape and Reel)2
TDFN33-12
PKXYY
AAT3688IWP-4.2-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 Information3
Index Area
0.43 ± 0.05
Detail "A"
0.45 ± 0.05
2.40 ± 0.05
3.00 ± 0.05
0.1 REF
C0.3
3.00 ± 0.05
1.70 ± 0.05
Top View
Bottom View
0.23 ± 0.05
Pin 1 Indicator
(optional)
0.05 ± 0.05
0.23 ± 0.05
0.75 ± 0.05
Detail "A"
Side View
All dimensions in millimeters.
1. XYY = assembly and date code.
2. Sample stock is generally held on part numbers listed in BOLD.
3. The leadless package family, which includes QFN, TQFN, DFN, TDFN and STDFN, has exposed copper (unplated) at the end of the lead terminals due to the manufacturing
process. A solder fillet at the exposed copper edge cannot be guaranteed and is not required to ensure a proper bottom solder connection.
Advanced Analogic Technologies, Inc.
3230 Scott Boulevard, Santa Clara, CA 95054
Phone (408) 737-4600
Fax (408) 737-4611
© 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. Except as provided in AnalogicTech’s terms and
conditions of sale, AnalogicTech assumes no liability whatsoever, and AnalogicTech disclaims any express or implied warranty relating to the sale and/or use of AnalogicTech products including liability or warranties
relating to fitness for a particular purpose, merchantability, or infringement of any patent, copyright or other intellectual property right. In order to minimize risks associated with the customer’s applications, adequate
design and operating safeguards must be provided by the customer to minimize inherent or procedural hazards. Testing and other quality control techniques are utilized to the extent AnalogicTech deems necessary to
support this warranty. Specific testing of all parameters of each device is not necessarily performed. AnalogicTech and the AnalogicTech logo are trademarks of Advanced Analogic Technologies Incorporated. All other
brand and product names appearing in this document are registered trademarks or trademarks of their respective holders.
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21