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PRODUCT DATASHEET
AAT3685
BatteryManagerTM
General Description
The AAT3685 BatteryManagerTM 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. The AAT3685 is available in a Pb-free, thermally-enhanced, space-saving 12-pin 3x3mm TDFN package and is rated over the -40C to +85C temperature range.
Lithium-Ion/Polymer Battery Charger
Features
* 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
* * * * * * 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 Input Hi/Lo Select
ADP/USB PWRSEL SETH RSETH RSETL SETL BAT TS C2 10F EN CHR
BATT+
AAT3685
GND
BATT-
DATA STAT1 STAT2
TEMP
Battery Pack
Serial Data
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PRODUCT DATASHEET
AAT3685
BatteryManagerTM
Pin Descriptions
Pin #
1 2 3 4 5 6 7 8 9 10 11 12 EP
Lithium-Ion/Polymer Battery Charger
Name
ADP/USB BAT GND CHR EN TS DATA STAT2 STAT1 PWRSEL SETL SETH
Type
In In/Out Ground In/Out In In/Out In/Out Out Out In 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 10k 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
1 2 3 4 5 6
12 11 10 9 8 7
SETH SETL PWRSEL STAT1 STAT2 DATA
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3685.2007.12.1.4
PRODUCT DATASHEET
AAT3685
BatteryManagerTM
AAT3685 Feature Options
Product
AAT3685 AAT3685-1
Lithium-Ion/Polymer Battery Charger
Internal Pull-Up Resistor on EN Pin
No Yes
Can Leave TS Pin Open
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
-0.3 to 7.0 -0.3 to 6.0 -0.3 to VP + 0.3 -40 to 150 300
Units
V V V C C
Thermal Information2
Symbol
JA PD
Description
Maximum Thermal Resistance (3x3mm TDFN) Maximum Power Dissipation
Value
50 2.0
Units
C/W W
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
AAT3685
BatteryManagerTM
Electrical Characteristics1
VADP = 5V, TA = -40C to +85C, unless otherwise noted. Typical values are at TA = 25C. Symbol Description Conditions Min
4.0 Rising Edge CC Charge Current = 500mA AAT3685: VBAT = 4.25V AAT3685-1: VBAT = 4.25V VBAT = 4V, ADP/USB Pin Open 4.158 2.8 No Connection on CHR Pin 4.3 1.9 50 CC Mode CC Mode 10 2.0 2.0 2000 2000 0.4 0.5 0.65 3.0 150 0.75 0.3 1 1.0 4.2 0.5 3.0 VBAT_EOC - 0.1 4.5 2.0
Lithium-Ion/Polymer Battery Charger
Typ
Max
5.5
Units
V V mV mA A A V % V V V V mA % V V
Operation ADP/USB Input Voltage Range VUVLO Under-Voltage Lockout Under-Voltage Lockout Hysteresis IOP Operating Current ISLEEP Sleep Mode Current ILeakage Reverse Leakage Current from BAT Pin VBAT_EOC1 End of Charge Voltage Accuracy VBAT/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 ICH/ICH Charge Current Regulation 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 On Resistance RDS(ON)U
1.5 1.0 3 4.242 3.15 4.64 2.1 1000
VIN = 5.5V
1. The AAT3685 output charge voltage is specified over the 0 to 70C ambient temperature range; operation over the -40C to +85C temperature range is guaranteed by design.
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3685.2007.12.1.4
PRODUCT DATASHEET
AAT3685
BatteryManagerTM
Electrical Characteristics1
VADP = 5V, TA = -40C to +85C, unless otherwise noted. Typical values are at TA = 25C. Symbol Description Conditions Min
1.6 0.4 1.6 AAT3685-1 Only, VEN = 5V STAT Pin Sinks 4mA 8.0 4.4 10 50 7.5 35 80 330 15 2.3 10 0.4 10 0.4
Lithium-Ion/Polymer Battery Charger
Typ
Max
Units
V V V V A V mA V % % % A mV V mV mA V V ns s kHz C
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 Output Low Voltage VSTAT ISTAT STAT Pin Current Sink Capability VOVP Over-Voltage Protection Threshold ITK/ICHG ITERM/ICHG ITERM/ICHG ITS TS1 TS2 I_DATA VDATA(H) VDATA)(L) SQPULSE tPERIOD fDATA TOVSD Pre-Charge Current Charge Termination Threshold Current Charge Termination Threshold Current Current Source from TS Pin TS Hot Temperature Fault TS Cold Temperature Fault DATA Pin Sink Current Input High Threshold Input Low Threshold Status Request Pulse Width System Clock Period Data Output Frequency Over-Temperature Shutdown Threshold
For For For For
SETH Mode SETL Mode SETH Mode SETL Mode 70 310 2.2 3.0 1.6
Threshold Hysteresis Threshold Hysteresis DATA Pin is Active Low State
90 350 2.4
0.4 Status Request 200 50 20 145
1. The AAT3685 output charge voltage is specified over the 0 to 70C ambient temperature range; operation over the -40C to +85C temperature range is guaranteed by design.
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PRODUCT DATASHEET
AAT3685
BatteryManagerTM
Typical Characteristics
IFASTCHARGE vs. RSET
10000 4.242
Lithium-Ion/Polymer Battery Charger
Battery Voltage vs. Supply Voltage
IFASTCHARGE (mA)
4.221 1000
VBAT (V) SETH
10 100 1000
SETL
100
4.200
4.179
10
1
4.158 4.5 4.75 5 5.25 5.5
RSET (k)
Supply Voltage (V)
Recharge Voltage vs. Temperature
4.140 4.130 4.120 4.110
End of Charge Voltage vs. Temperature
4.242
4.221
VRCH (V)
4.100 4.090 4.080 4.070 4.060 4.050 4.040 -50 -25 0 25 50 75 100
VBAT (V)
4.200
4.179
4.158 -50 -25 0 25 50 75 100
Temperature (C)
Temperature (C)
Preconditioning Threshold Voltage vs. Temperature
3.05 3.04 3.03 3.02 3.01 3.00 2.99 2.98 2.97 2.96 2.95 -50 -25 0 25 50 75 100
Preconditioning Charge Current vs. Temperature
(SETH; SETH = 3.83k)
120
110
ICH (mA)
VMIN (V)
100
90
80 -50 -25 0 25 50 75 100
Temperature (C)
Temperature (C)
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PRODUCT DATASHEET
AAT3685
BatteryManagerTM
Typical Characteristics
Fast Charge Current vs. Temperature
(SETH; SETH = 3.83k)
1100 1080 1060 1040
Lithium-Ion/Polymer Battery Charger
Charging Current vs. Battery Voltage
(SETH; SETH = 3.83k)
1200 1000 800
ICH (mA)
1020 1000 980 960 940 920 900 -50 -25 0 25 50 75 100
ICH (mA)
600 400 200 0 2.5 3 3.5 4 4.5
Temperature (C)
Battery Voltage (V)
Charging Current vs. Battery Voltage
(SETL; SETL = 40.2k)
120 100 80 60 40 20 0 2.5 3 3.5 4 4.5
Fast Charge Current vs. Supply Voltage
(SETH; SETH = 3.83k)
1200
VBAT = 3.3V
1000 800 600 400 200 0 4 4.25 4.5 4.75 5 5.25 5.5 5.75 6
VBAT = 3.9V VBAT = 3.5V
ICH (mA)
Battery Voltage (V)
ICH (mA)
Supply Voltage (V)
Fast Charge Current vs. Supply Voltage
(SETL; SETL = 40.2k)
120 1200
Fast Charge Current vs. Supply Voltage
(SETH; SETH = 3.83k) 0C
1000
VBAT = 3.5V
100
VBAT = 3.9V ICH (mA) ICH (mA)
80 60 40 20 0 4 4.5 5 5.5 6 6.5 800
70C 25C
VBAT = 3.3V
600 400 200 0 4.40
4.50
4.60
4.70
4.80
4.90
5.00
Supply Voltage (V)
Supply Voltage (V)
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PRODUCT DATASHEET
AAT3685
BatteryManagerTM
Typical Characteristics
VIH vs. Supply Voltage
EN Pin (Rising)
1.4 1.3 1.2 1.1 1.4 1.3 1.2
Lithium-Ion/Polymer Battery Charger
VIL vs. Supply Voltage
EN Pin (Falling)
-40C
+25C VIL (V)
1.1 1.0 0.9 0.8 0.7
-40C
+25C
VIH (V)
1.0 0.9 0.8 0.7 0.6 0.5 0.4 4.2 4.4 4.6 4.8 5 5.2 5.4 5.6 5.8 6
+85C
0.6 0.5 0.4 4.2 4.4 4.6 4.8
+85C
5 5.2 5.4 5.6 5.8 6
Supply Voltage (V)
Supply Voltage (V)
VIH vs. Supply Voltage
PWRSEL (Rising)
1.4 1.3 1.2 1.1 1.4 1.3
VIL vs. Supply Voltage
PWRSEL (Falling)
-40C
+25C VIL (V)
1.2 1.1 1.0 0.9 0.8 0.7 0.6 0.5 0.4
-40C
+25C
VIH (V)
1.0 0.9 0.8 0.7 0.6 0.5 0.4 4.2 4.4 4.6 4.8 5 5.2 5.4 5.6 5.8 6
+85C
+85C
4.2
4.4
4.6
4.8
5
5.2
5.4
5.6
5.8
6
Supply Voltage (V)
Supply Voltage (V)
Supply Current vs. SETH Resistor
0.80 0.70 0.60 USB VBUS (200mV/div) USB Charge Current (200mA/div)
Charge Current vs. Time
(SETH; SETH = 8.06k)
IQ (mA)
0.50 0.40 0.30 0.20 0.10 0.00 1 10
Constant Current
Charge Reduction Mode Activated
Pre-Conditioning
USB Peripheral Current Consumption (200mA/div) 0 2 4 6 8 10
100
1000
SETH Resistor (k)
Time (sec)
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PRODUCT DATASHEET
AAT3685
BatteryManagerTM
Typical Characteristics
Temperature Sense Output Current vs. Temperature
88
Lithium-Ion/Polymer Battery Charger
TS Pin CUrrent (A)
86 84 82 80 78 76 74 72 -50 -25 0 25 50 75 100
Temperature (C)
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PRODUCT DATASHEET
AAT3685
BatteryManagerTM
Functional Block Diagram
Reverse Blocking
Lithium-Ion/Polymer Battery Charger
ADP/USB PWRSEL SETH SETL CHR
Charge Reduction Loop
BAT
Current Compare CV/ Precharge
Constant Current
Charge Control
UVLO
OverTemperature Protect
STAT1 STAT2
Charge Status
80A
DATA
Serial Data
TS
Window Comparator
IC enable EN GND
Functional Description
The AAT3685 is a highly integrated single cell lithiumion/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 lithium-ion/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 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.
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.
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PRODUCT DATASHEET
AAT3685
BatteryManagerTM
Preconditioning Trickle Charge Phase Charge Complete Voltage Regulated Current I = Max CC Constant Current Charge Phase
Lithium-Ion/Polymer Battery Charger
Constant Voltage Charge Phase
Constant Current Mode Voltage Threshold
Trickle Charge and Termination Threshold
I = CC / 10
Figure 1: Current vs. 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.
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 0.3A in sleep mode (1A 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.
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. 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.
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PRODUCT DATASHEET
AAT3685
BatteryManagerTM
System Operation Flow Chart
Switch On
Lithium-Ion/Polymer Battery Charger
Sleep Mode
No
UVLO VP > VUVLO
Yes
Input Power
SETL Current Loop Power On Reset SETH Current Loop Fault Conditions Monitor OV, OT No Yes
0
Input Detect PWRSEL= ?
1
Shut Down Mode No Battery Temp. Fault
Yes
Battery
Temperature Monitor
VTS1 < TS < VTS2
Input Voltage Regulation Enable
No Recharge Test VRCH > VBAT Yes Preconditioning Test VMIN > VBAT Yes Low Current Conditioning Charge
No Port Voltage Test VADP/USB < VADP/USB_CHR
No Current Charging Mode
Yes
Current Phase Test VEOC > VBAT No
Yes
Charge Current Reduction
Voltage Phase Test IBAT > ITERM No Charge Completed
Yes
Voltage Charging Mode
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PRODUCT DATASHEET
AAT3685
BatteryManagerTM
Application Information
USB System Power Charging
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. ICC
50 75 100 200 300 400 500 600 700 800 900 1000
Lithium-Ion/Polymer Battery Charger
SETH RSET (k)
86.6 57.6 42.2 21.0 13.7 10.2 8.06 6.65 5.62 4.87 4.32 3.83
SETL RSET (k)
86.6 57.6 42.2 20.5 13.7 10.2 8.06 6.65 5.62 4.87 4.32 3.83
Table 1: Recommended RSET Values.
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 fast charge current to maintain port integrity and protect the host system. 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 10k resistor from the CHR pin directly to the ADP/ USB input pin. The following equation may be used to approximate a USB charge reduction threshold below 4.5V: Eq. 1: VADP/USB_CHR = 2.0V / where R11/R12 << 1M.
VADP/USB ADP/USB
R11
1.025M
CHR VCHR = 2.0V
R12 825k
Figure 2: Internal Equivalent Circuit for the CHR Pin.
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
R12 R12 + R11
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PRODUCT DATASHEET
AAT3685
BatteryManagerTM
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 under-voltage 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 automatically 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.
Lithium-Ion/Polymer Battery Charger
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.
10000
IFASTCHARGE (mA)
1000
USBL
100
USBH
10 1 10 100 1000
RSET (k)
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 overvoltage 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.
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.
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.
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.
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.
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3685.2007.12.1.4
PRODUCT DATASHEET
AAT3685
BatteryManagerTM
After the system recovers from a temperature fault, the device will resume charging operation. 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 10k at room temperature (25C). The TS pin has been specifically designed to source 80A 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 10k resistor. Alternatively, on the AAT3685-1, the TS pin may be left open.
Lithium-Ion/Polymer Battery Charger
Event Description
Charge Disabled or Low Supply Charge Enabled Without Battery Battery Charging Charge Completed Fault
STAT1
Off Flash1 On Off On
STAT2
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) = Example:
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.
(VAPD/USB - VF(LED)) ILED(STAT1/2)
RB(STAT1) =
(5.0V - 2.0V) = 1.5k 2mA
Note: Red LED forward voltage (VF) is typically 2.0V @ 2mA. Table 2 shows the four status LED display conditions.
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.
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.
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PRODUCT DATASHEET
AAT3685
BatteryManagerTM
N
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
Lithium-Ion/Polymer Battery Charger
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 1.5k 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
DATA Report Status
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
VPULL-UP 3mA
Data Timing
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 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.
Table 3: Serial Data Report Table. 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
1.8V to 5.0V
IN
AAT3685 Status Control
OUT
RPULL_UP DATA Pin
GPIO
IN
OUT
P GPIO Port
Figure 4: Data Pin Application Circuit.
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PRODUCT DATASHEET
AAT3685
BatteryManagerTM
Timing Diagram
Lithium-Ion/Polymer Battery Charger
SQ
SQPULSE System Reset System Start
PDATA
CK
TSYNC TLAT TOFF
Data
TDATA(RPT) = TSYNC + TLAT < 2.5 PDATA TOFF > 2 PDATA
N=1
N=2
N=3
Thermal Considerations
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 50C/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. First, the maximum power dissipation for a given situation should be calculated: Eq. 4: PD = [(VIN - VBAT) * ICC + (VIN * IOP)] Where: PD VIN VBAT ICC IOP = = = = Total Power Dissipation by the Device Input Voltage Level, VADP/USB 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
ficiently mounted to a PCB layout and the internal thermal loop temperature threshold. Eq. 5: TA = TJ - (JA * 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 JA = 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 VBAT ICC IOP TJ JA = = = = = = 5.0V 3.0V 500mA 0.75mA 140C 50C/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)
Next, the maximum operating ambient temperature for a given application can be estimated based on the thermal resistance of the 3x3mm TDFN package when suf-
= 1.00375W
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PRODUCT DATASHEET
AAT3685
BatteryManagerTM
The maximum ambient temperature before the AAT3685 thermal limit protection will shut down charging can now be calculated using Equation 5: Eq. 7: TA = 140C - (50C/W * 1.00375W)
Lithium-Ion/Polymer Battery Charger
plugged" in. Likewise, a 10F 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 1F ceramic capacitor on the BAT pin to maintain circuit stability. This value should be increased to 10F 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 10F may be required to prevent the device from cycling on and off when no battery is present.
= 89.81C
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 89.81C.
Capacitor Selection
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 1F to 22F 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 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 10F should be used. A larger input capacitor in this application will minimize switching or power bounce effects when the power supply is "hot
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).
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PRODUCT DATASHEET
AAT3685
BatteryManagerTM
AAT3685 Evaluation Board Layout
Lithium-Ion/Polymer Battery Charger
Figure 5: AAT3685 Evaluation Board Component Side Layout.
Figure 6: AAT3685 Evaluation Board Solder Side Layout.
AAT3685 Evaluation Board Schematic Diagram
ON/OFF J1
123
PWRSEL J2
123
Mini-B GND ID D+ DADP/USB
5 4 3 2 1
HI
LO
C2 TB1 ADP/USB GND
1 2
RED GRN LED D2 LED D1
R9 1.5K
10F R3 R2 Open Open
1 5
U1
AAT3685
PWRSEL STAT2 STAT1 DATA
10 8 9 7 11 12
R5 1.5K
R6 1.5K
ADP/USB EN BAT
BAT TS GND TB2
1 2 3
2
DATA
C1 10F
4
CHR TS
SETL SETH
6
GND
3
R8 8.06K
R7 SW1 40.2K
R4 10K
R1 Open
TDFN33-12
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PRODUCT DATASHEET
AAT3685
BatteryManagerTM Lithium-Ion/Polymer Battery Charger
AAT3685 Evaluation Board Bill of Materials (BOM)
Quantity
1 1 1 1 2 1 1 2 1 3 1 1 1 1
Description
Test Pin Connecting Terminal Block, 2.54mm, 2 Pos Connecting Terminal Block, 2.54mm, 3 Pos USB 2.0 Receptacle, 5 Pos Capacitor, Ceramic, 10F 6.3V 10% X5R 0805 Typical Red LED, Super Bright Typical Green LED Header, 3-Pin Resistor, 10k 1/16W 5% 0603 SMD Resistor, 1.5k 1/16W 1% 0603 SMD Resistor, 40.2k 1/16W 1% 0603 SMD Resistor, 8.06k 1/16W 1% 0603 SMD Switch Tact 6mm SPST H = 5.0mm AAT3685 Lithium-Ion/ Polymer Battery Charger
Desig.
DATA USB, GND BAT, GND, TS USB C1, C2 D1 D2 J1, J2 R4 R5, R6, R9 R7 R8 SW1 U1
Footprint
PAD TBLOK2 TBLOK3 USB-MINI-B 0805 1206LED 1206LED HEADER2MM-3 0603 0603 0603 0603 SWITCH TDFN33-12
Manufacturer
Mill-Max Phoenix Contact Phoenix Contact Hirose Electronic Co. Ltd. Murata Chicago Miniature Lamp Chicago Miniature Lamp Sullins Panasonic/ECG Panasonic/ECG Panasonic/ECG Panasonic/ECG ITT Industries/ C&K Div. AnalogicTech
Part Number
6821-0-0001-00-00-08-0 277-1274-ND 277-1273-ND H2959CT-ND 490-1717-1-ND CMD15-21SRC/TR8 CMD15-21VGC/TR8 6821-0-0001-00-00-08-0 P10KCFCT-ND P1.5KCGCT-ND P40.2KHTR-ND P8.06KHCT-ND CKN9012-ND AAT3685IWP
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3685.2007.12.1.4
PRODUCT DATASHEET
AAT3685
BatteryManagerTM
Ordering Information
Package
TDFN33-12 TDFN33-12
Lithium-Ion/Polymer Battery Charger
Marking1
RNXYY TMXYY
Part Number (Tape and Reel)2
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
TDFN33-12
Index Area Detail "A" 0.43 0.05
0.1 REF 3.00 0.05 2.40 0.05 C0.3 0.45 0.05
Pin 1 Indicator (optional)
3.00 0.05
1.70 0.05
Top View
Bottom View Detail "A"
0.75 0.05
0.05 0.05
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
(c) 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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0.23 0.05
0.23 0.05
21

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