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1.0A USB Port/Adapter Lithium-Ion/Polymer Battery Charger General Description
The AAT3690 BatteryManager is a highly integrated single-cell lithium-ion/polymer battery charger IC designed to operate with USB port and AC adapter inputs. It requires the minimum number of external components. The AAT3690 precisely regulates battery charge voltage and current for 4.2V lithium-ion/polymer battery cells. Adapter charge current rates can be programmed up to 1.0A. In the absence of an adapter and with a USB port connected, the battery can also be charged by USB power. The USB charge current can be programmed up to 1A. A Charge Reduction Loop is also built in to allow users to charge the battery with the available current from a USB port, while keeping the port voltage regulated. USB charging is disabled when an adapter is present.
AAT3690
Features
* * * *
BatteryManagerTM
Battery temperature and charge state are fully monitored for fault conditions. In the event of an over-voltage or over-temperature condition, the device will automatically shut down, thus protecting www..com the charging device, control system, and the batApplications tery under charge. Status monitor output pins are provided to indicate the battery charge status by * Cellular Telephones directly driving two external LEDs. * Digital Still Cameras * Hand-Held PCs The AAT3690 is available in a Pb-free, thermally* MP3 Players enhanced, space-saving 12-pin 3x3mm TDFN * Personal Data Assistants (PDAs) package and is rated over the -40C to +85C tem* Other Lithium-Ion/Polymer Battery-Powered perature range. Devices
* * * * * * * * * * *
USB/AC Adapter System Power Charger -- USB: Programmable up to 1.0A -- Adapter: Programmable up to 1.0A 4.0V to 5.5V Input Voltage Range Adapter Presence Automatically Disables USB Charging High Level of Integration With Internal: -- Charging Devices -- Reverse Blocking Diodes -- Current Sensing Automatic Recharge Sequencing Digital Thermal Regulation in ADP Charge Charge Reduction Loop in USB Charge Battery Temperature Monitoring Full Battery Charge Auto Turn-Off Over-Current Protection Over-Voltage Protection Emergency Thermal Protection Power On Reset and Soft Start Serial Interface Status Reporting 12-Pin 3x3mm TDFN Package
Typical Application
Enable USB Input
USB USBSET RSETUSB EN BAT TS C2 10F
BATT+
AAT3690
ADP Input
RSETADP ADP ADPSET STAT1
BATT-
CT CT
GND STAT2
TEMP
Battery Pack
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1
1.0A USB Port/Adapter Lithium-Ion/Polymer Battery Charger Pin Descriptions
Pin #
1, 10 2 3 4 5 6 7 8 9
AAT3690
Name
USB BAT ADP GND EN TS STAT2 STAT1 CT
Type
In In/Out In Ground In In/Out Out Out In/Out
Function
USB power supply input. Battery charging and sensing. Adapter power supply input. Ground connection. Enable pin. Logic high enables the IC. When open, this pin is internally pulled up to the higher voltage of ADP and USB inputs. Connect to 10k NTC thermistor. When TS is open, the battery temperature sensing function is disabled. 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. Timing capacitor to adjust internal watchdog timer. Set maximum charge time for adapter powered CC and CV charge modes. The watchdog timer only sets the timers for adapter battery charging; there is no timeout for the battery charging from the USB input. If timing function is not needed, terminate this pin to ground. Connect a resistor between this pin and GND to set USB charging current. Connect a resistor between this pin and GND to set adapter charging current. Exposed paddle (bottom); connect to GND directly beneath package.
11 12 EP
USBSET ADPSET
In/Out In/Out
Pin Configuration
TDFN33-12 (Top View)
USB BAT ADP GND EN TS
1 2 3 4 5 6
12 11 10 9 8 7
ADPSET USBSET USB CT STAT1 STAT2
2
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1.0A USB Port/Adapter Lithium-Ion/Polymer Battery Charger Absolute Maximum Ratings1
Symbol
VP VP VN TJ TLEAD
AAT3690
Description
USB, ADP, <30ms, Duty Cycle <10% USB, ADP Continuous BAT, USBSEL, USBSET, ADPSET, STAT1, STAT2, TS, CT, 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 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 a FR4 board. 3690.2007.01.1.2
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1.0A USB Port/Adapter Lithium-Ion/Polymer Battery Charger Electrical Characteristics1
VADP = 5V, TA = -40C to +85C, unless otherwise noted. Typical values are at TA = 25C. Symbol
Operation USB, ADP
AAT3690
Description
Conditions
Min
4.0 4.25
Typ
Max Units
5.5 V V V mV mA A A 4.242 V % V V mA % V V
USB Port or Adapter Voltage Range ADP Voltage Level to Disable VU_DSBL USB Charging Under-Voltage Lockout VUVLO Under-Voltage Lockout Hysteresis IOP Operating Current ISLEEP Sleep Mode Current Reverse Leakage Current from ILeakage BAT Pin Voltage Regulation VBAT_EOC1 End of Charge Voltage Accuracy VBAT/VBAT EOC Voltage Tolerance VRCH Battery Recharge Voltage Threshold VUSB_CHR USB Charge Reduction Regulation Current Regulation ICH Charge Current
4.5 3.0 150 0.75 2.0 1.0
4.7
Rising Edge CC Charge Current = 500mA VBAT = 4.25V VBAT = 4V, USB, ADP Pins Open 4.158
1.5 5.0
4.2 0.5 VBAT_EOC - 0.1 4.5
4.3 ADP Input USB Input In CC Mode In CC Mode 100 50
4.64 1000 1000
ICH/ICH Charge Current Regulation Tolerance VADPSET ADPSET Pin Voltage VUSBSET USBSET Pin Voltage KIADP Current Set Factor: ICHARGE/IADPSET KIUSB Current Set Factor: ICHARGE/IUSBSET Charging Devices Adapter Charging Transistor RDS(ON)A On Resistance USB Charging Transistor RDS(ON)U On Resistance
10 2.0 2.0 4000 2000 0.2 0.4 0.25 0.5 0.35 0.65
VIN = 5.5V VIN = 5.5V

1. The AAT3690 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.
4
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1.0A USB Port/Adapter Lithium-Ion/Polymer Battery Charger Electrical Characteristics1
VADP = 5V, TA = -40C to +85C, unless otherwise noted. Typical values are at TA = 25C. Symbol Description Conditions Min Typ Max
1.6 0.4 CCT = 100nF, VADP = 5.5V CCT = 100nF, VADP = 5.5V STAT Pin Sinks 4mA 8.0 4.4 105 7.5 Threshold Hysteresis Threshold Hysteresis 70 310 2.2 80 330 15 2.3 10 90 110 85 145 90 350 2.4 3.0 3.0 0.4
AAT3690
Units
V V Hour Hour V mA V %ICH_CC % A mV V mV C C C C
Logic Control / Protection VEN(H) Input High Threshold VEN(L) Input Low Threshold Constant Current Mode Time Out TC (ADP mode only) Constant Voltage Mode Time Out TV (ADP mode only) VSTAT Output Low Voltage ISTAT STAT Pin Current Sink Capability VOVP Over-Voltage Protection Threshold IOCP Over-Current Protection Threshold Charge Termination Threshold Current ITERM/ICHG ITS Current Source from TS Pin TS1 TS2 TREG TLOOP_IN TLOOP_OUT TOVSD TS Hot Temperature Fault TS Cold Temperature Fault Thermal Loop Regulation Thermal Loop Entering Threshold Thermal Loop Exiting Threshold Over-Temperature Shutdown Threshold
1. The AAT3690 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. 3690.2007.01.1.2
5
1.0A USB Port/Adapter Lithium-Ion/Polymer Battery Charger Typical Characteristics
IFASTCHARGE vs. RSET
10000
AAT3690
Battery Voltage vs. Supply Voltage
4.242
IFASTCHARGE (mA)
4.221
1000
VBAT (V)
USB
4.200
ADP 100 USB
ADP
4.179
10 1 10 100 1000
4.158 4.5
4.75
5
5.25
5.5
RSET (k)
Supply Voltage (V)
Recharge Voltage vs. Temperature
4.14 4.13 4.12 4.11
End of Charge Voltage vs. Temperature
4.242
4.221
VRCH (V)
4.09 4.08 4.07 4.06 4.05 4.04 -50 -25 0 25 50 75 100
VBAT (V)
4.10
ADP USB
ADP
4.200
4.179
USB
4.158 -50
-25
0
25
50
75
100
Temperature (C)
Temperature (C)
Fast Charge Current vs. Temperature
(RADPSET = 8.06k; RUSBSET = 8.06k)
1100 1080 1060 540 530 520 510 500 490 480 470 460 450 -25 0 25 50 75 440 100
Adapter Charging Current vs. Battery Voltage
(RADPSET = 8.06k)
1.2 1.0
ICH ADP (mA)
1040 1020 1000 980 960 940 920 900 -50
USB
ICH USB (mA)
0.8
ICH (A)
0.6 0.4 0.2 0.0 2.5
ADP
2.9
3.3
3.7
4.1
4.5
Temperature (C)
Battery Voltage (V)
6
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1.0A USB Port/Adapter Lithium-Ion/Polymer Battery Charger Typical Characteristics
USB Charging Current vs. Battery Voltage
(RUSBSET = 8.06k)
600 500 400 300 200 100 0 2.5
AAT3690
Adapter Fast Charge Current vs. Supply Voltage
(RADPSET = 8.06k)
1200 1000 800 600 400 200 0
VBAT = 3.3V VBAT = 3.9V VBAT = 3.5V
ICH (mA)
3
3.5
4
4.5
ICH (mA)
4
4.5
5
5.5
6
Battery Voltage (V)
Supply Voltage (V)
USB Fast Charge Current vs. Supply Voltage
(RUSBSET; USB = 8.06k)
600 500 400 300 200 100 0 4 4.25 4.5 4.75 5 5.25 5.5 5.75 6
USB Fast Charge Current vs. Supply Voltage
(RUSBSET; USB = 8.06k)
600 500
VBAT = 3.3V VBAT = 3.5V VBAT = 3.9V
0C 25C 70C
ICH (mA)
ICH (mA)
400 300 200 100 0
4.4
4.5
4.6
4.7
4.8
4.9
5
Supply Voltage (V)
Supply Voltage (V)
VIH vs. Supply Voltage
EN Pin (Rising)
1.4 1.3 1.2 1.1 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 1.4 1.3 1.2 1.1 1.0 0.9 0.8 0.7 0.6 0.5 0.4 4.2 4.4
VIL vs. Supply Voltage
EN Pin (Falling)
-40C
25C
-40C
25C
VIH (V)
85C
VIH (V)
85C
4.6 4.8 5 5.2 5.4 5.6 5.8 6
Supply Voltage (V)
Supply Voltage (V)
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1.0A USB Port/Adapter Lithium-Ion/Polymer Battery Charger Typical Characteristics
Adapter Mode Supply Current vs. ADPSET Resistor
0.8 0.7 0.6
USB VBUS (200mV/div) USB Charge Current (100mA/div) Charge Reduction Mode Activated
AAT3690
USB Charge Current vs. Time
(RUSBSET = 8.06k)
IQ (mA)
0.5 0.4 0.3 0.2 0.1 0.0 1 10
Constant Current
USB Peripheral Current Consumption (100mA/div)
100
1000
0
2
4
6
8
10
ADPSET Resistor (k)
Time (sec)
Counter Timeout vs. Temperature
(CT = 0.1F)
10
CT Pin Capacitance vs. Counter Timeout
0.5 0.4 0.3 Constant Current Timeout 0.2 0.1 0.0
Counter Timeout (%)
8 4 2 0 -2 -4 -6 -8 -10 -50 -25 0 25 50 75 100 0 2 4 6 8 10
Temperature (C)
Capacitance (F)
6
Time (hours)
Temperature Sense Output Current vs. Temperature
88
TS Pin Current (A)
86 84 82 80 78 76 74 72 -50 -25 0 25 50 75 100
Temperature (C)
8
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1.0A USB Port/Adapter Lithium-Ion/Polymer Battery Charger Functional Block Diagram
Reverse Blocking
AAT3690
USB USBSET
Charge Reduction Loop Current Compare CV
Constant Current
Charge Control
UVLO
BAT
ADPSET ADP
Current Compare
OverTemperature Protect
Reverse Blocking
Voltage Sense
Window Comparator
80A
TS
Charge Status
STAT1 STAT2
IC enable
Watchdog Timer
CT
EN GND
Functional Description
The AAT3690 is a highly integrated single-cell lithium-ion/polymer battery charger IC designed to operate with USB port and AC adapter inputs, while requiring a minimum number of external components. The AAT3690 precisely regulates battery charge voltage and current for 4.2V lithium-ion/polymer battery cells. The adapter charge input constant current level can be programmed up to 1.0A for rapid charging applications. In the absence of a high-current adapter input source, the AAT3690 can be powered from a USB port VBUS supply. The USB constant charge current can be externally programmed for maximum constant current charge levels up to 1A. The USB mode has an automatic Charge Reduction Loop control to allow users to charge the battery with limited available current from a USB port while maintaining the regulated port volt3690.2007.01.1.2
age. 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. The USB charge function is automatically disabled when an adapter input power source greater than 4.4V is present. Status monitor output pins are provided to indicate the battery charge status by directly driving two external LEDs. Battery temperature and charge state are fully monitored for fault conditions. In the event of an overvoltage or over-temperature condition, 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 AAT3690 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. 9
1.0A USB Port/Adapter Lithium-Ion/Polymer Battery Charger
Charging Operation
Regardless of which charge input function is selected (i.e., either the adapter input or USB input), the AAT3690 has three basic modes for the battery charge cycle: constant current/fast charge; constant voltage; and end of charge (see Figure 1).
Constant Current Charge Phase Charge Complete Voltage Regulated Current I = Max CC Constant Voltage Charge Phase
AAT3690
I = CC/10
Figure 1: Current vs. Voltage Profile During Charging Phases.
Fast Charge / Constant Current Charging
When enabled, the AAT3690 begins constant-current fast charging. The fast charge Constant Current (ICC) amplitude is determined by the charge mode, ADP or USB, and is programmed by the user via the RSETADP and RSETUSB resistors. The AAT3690 remains in constant current charge mode until the battery reaches the voltage regulation point, VBAT.
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 standby state. The charger will remain in a standby state until the battery voltage decreases to a level below the battery recharge voltage threshold (VRCH). When the input supply is disconnected or drops below UVLO or EN = 0, the charger will automatically enter power-saving sleep mode. Consuming an ultra-low 2A in sleep mode, the AAT3690 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 AAT3690 input voltage drops, the device will enter the sleep mode and automatically resume charging once the input supply has recovered from its fault condition.
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.
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1.0A USB Port/Adapter Lithium-Ion/Polymer Battery Charger
System Operation Flow Chart
AAT3690
ADP
Power Select
Yes
UVLO VP > VUVLO No
Yes
Switch On No
USB ADP Loop Enable
Sleep Sleep Mode Mode
Power On Power On Reset Reset
USB Loop No Timing Fault Conditions Monitor OV, OT No Battery Temp. Monitor VTS1 < TS < VTS2 No
Thermal Loop Enable
Device Temp. Monitor TJ > 110C Yes
Yes Expire Thermal Loop Current Reduction in ADP Charging Mode
Yes
Shutdown Mode Battery Temp. Fault
Charge Safety Timer Set
No
Recharge Test VRCH > VBAT
Yes
Current Phase Test VEOC > VBAT No
Yes
Current Charging Mode
Voltage Phase Test IBAT > ITERM No Charge Completed
Yes
Voltage Charging Mode
USB Loop USB Loop Current Current Reduction in USB Reduction in USB Charging Mode Charging Mode Yes No
USB Voltage Regulation Enable
USB Voltage Test VUSB < 4.5V
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1.0A USB Port/Adapter Lithium-Ion/Polymer Battery Charger Application Information
AC Adapter / USB System Power Charging
Adapter Mode In the adapter mode, constant current charge levels up to 1.0A can be programmed by the user. The AAT3690 system control will always select the adapter input over the USB supply input whenever adapter voltage is present on the ADP pin. The AAT3690 will operate from the adapter input over a 4.0V to 5.5V range. The constant current fast charge current for the adapter input mode is set by the RSETADP resistor connected between ADPSET and ground. Refer to Table 1 for recommended RSETADP values for a desired constant current charge level. The precise charging function in the adapter mode may be read from the status LEDs. Please refer to the Battery Charge Status Indication discussion in this datasheet for further details. Thermal Loop Control Due to the integrated nature of the linear charging control pass device for the adapter mode, a special thermal loop control system has been employed to maximize charging current under all operating conditions. The thermal management system measures the internal circuit die temperature and reduces the fast charge current when the device exceeds a preset internal temperature control threshold. Once the thermal loop control becomes active, the fast charge current is initially reduced by a factor of 0.44. The initial thermal loop current can be estimated by the following equation: fast charge current level or until an equilibrium current is discovered and maximized for the given ambient temperature condition. In the manner the thermal loop controls the system charge level, the AAT3690 will always provide the highest level of constant current in the fast charge mode possible for any given ambient temperature condition. Adapter Input Charge Inhibit and Resume The AAT3690 has an under-voltage lockout and power on reset feature so that if the input supply to the adapter pin drops below the UVLO threshold the charger will suspend charging and shut down. When power is re-applied to the adapter pin or the UVLO condition recovers and VADP > VBAT, 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.
AAT3690
USB Mode
The AAT3690 provides an input for intelligent USB charging. When no voltage is present on the adapter input pin, the charge controller will automatically switch to accepting power from the USB input. The USB charge may be user programmed to any level between 50mA and 1A by selecting the appropriate resistor values for RSETUSB. Refer to Table 1 for recommended RSETUSB values for the desired USB input constant current charge levels. USB Charge Reduction In many instances, product system designers do not know the real properties of a potential USB port used to supply power to the battery charger. Typically, powered USB ports 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 AAT3690 will automatically reduce USB fast charge current to maintain port integrity and protect the host system.
ITLOOP = ICC * 0.44
The thermal loop control re-evaluates the circuit die temperature every three seconds and adjusts the fast charge current back up in small steps to the full
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3690.2007.01.1.2
1.0A USB Port/Adapter Lithium-Ion/Polymer Battery Charger
ADP RSET (k)
N/A N/A 84.5 43.2 28.0 21.0 16.9 13.3 11.5 10.2 9.09 8.06
AAT3690
ICC
50 75 100 200 300 400 500 600 700 800 900 1000
USB 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
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 both Adapter and USB input modes are programmed with set resistors placed between the ADPSET and USBSET pins and ground. The accuracy of the fast charge is dominated by the tolerance of the set resistor used. For this reason, 1% tolerance metal film resistors are recommended for the set resistor function. ADP fast charge constant current levels from 100mA to 1.0A may be set by selecting the appropriate resistor value from Table 1. The USB charge may be set to any level between 50mA and 1.0A depending upon the system design requirements for a given USB charge application. Refer to Table 1 and Figure 2 for recommended RSETUSB values.
Table 1: Resistor Values. The USB charge reduction system becomes active when the voltage on the USB input falls below the USB charge reduction threshold, which is typically 4.5V. 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. USB Input Charge Inhibit and Resume The AAT3690 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.
10000
IFASTCHARGE (mA)
1000
ADP USB
100
Enable / Disable
The AAT3690 provides an enable function to control the charger IC on and off. The enable (EN) pin is active high and is internally pulled up to the higher voltage of ADP and USB supplies. When pulled to a logic low level, the AAT3690 will be shut down
10
1
10
100
RSET (k)
Figure 2: IFASTCHARGE vs. RSET.
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1.0A USB Port/Adapter Lithium-Ion/Polymer Battery Charger
Protection Circuitry
Programmable Watchdog Timer The AAT3690 contains a watchdog timing circuit for the adapter input charging mode. No watchdog timing functions are active for the USB input mode. Typically, a 0.1F ceramic capacitor is connected between the CT pin and ground. When a 0.1F ceramic capacitor is used, the device will time a shutdown condition if the fast charge mode exceeds three hours. When the device transitions to the constant voltage mode, the timing counter is reset and will time out after three hours and shut down the charger. Mode
Fast Charge (CC) Time Out Constant Voltage (CV) Mode Time Out
AAT3690
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 overvoltage protection threshold (VOVP). If an over-voltage condition occurs, the AAT3690 charge control will shut down the device until voltage on the BAT pin drops below the over-voltage protection threshold (VOVP). The AAT3690 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.
Over-Temperature Shutdown
The AAT3690 has a thermal protection control circuit which will shut down charging functions should the internal die temperature exceed the preset thermal limit threshold.
Time
3 hours 3 hours
Summary for a 0.1F Used for the Timing Capacitor. The CT pin is driven by a constant current source and will provide a linear response to increases in the timing capacitor value. Thus, if the timing capacitor were to be doubled from the nominal 0.1F value, the time-out times would be doubled. If the programmable watchdog timer function is not needed, it may be disabled by connecting the CT pin to ground. The CT pin should not be left floating or un-terminated, as this will cause errors in the internal timing control circuit. The constant current provided to charge the timing capacitor is very small, and this pin is susceptible to noise and changes in capacitance value. Therefore, the timing capacitor should be physically located on the printed circuit board layout as closely as possible to the CT pin. Since the accuracy of the internal timer is dominated by the capacitance value, 10% tolerance or better ceramic capacitors are recommended. Ceramic capacitor materials such as X7R and X5R type are a good choice for this application.
Battery Temperature Fault Monitoring
In the event of a battery over-temperature condition, the charge control will turn off the internal pass device. The STAT LEDs will display a system fault. After the system recovers from a temperature fault, the device will resume charging operation. The AAT3690 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 to 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 AAT3690 will signal the fault condition. If the use of the TS pin function is not required by the system, it can be left open or terminated to ground using a 10k resistor.
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1.0A USB Port/Adapter Lithium-Ion/Polymer Battery Charger
Battery Charge Status Indication
The AAT3690 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. 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 AAT3690. These two pins are simple switches to connect the 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 using the STAT1 pin and a single LED. Using two LEDs and both STAT pins simply gives the user more information to the charging states. Refer to Table 2 for LED display definitions. The LED anodes should be connected to either VUSB or VADP, depending upon the system design requirements. The LEDs should be biased with as little current as necessary to create reasonable illumination; therefore, a ballast resistor should be placed between the LED cathodes and the STAT1/2 pins. LED current consumption will add to the overall thermal power budget for the device package, so it is wise to keep the LED drive current to a minimum. 2mA should be sufficient to drive most low-cost green or red 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: Example: For connection to the adapter supply:
RB(STAT1/2) = VADP - VF(LED) ILED(STAT1/2)
AAT3690
RB(STAT1) =
5.5V - 2.0V = 1.75k 2mA
Note: Red LED forward voltage (VF) is typically 2.0V @ 2mA. For connection to the USB supply:
RB(STAT1/2) = VUSB - VF(LED) ILED(STAT1/2)
Example:
RB(STAT2) =
5.0V - 3.2V = 900 2mA
Note: Green LED forward voltage (VF) is typically 3.2V @ 2mA. The status LED display conditions are described in Table 2.
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: Status LED Display Conditions.
1. Flashing rate depends on output capacitance. 3690.2007.01.1.2
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1.0A USB Port/Adapter Lithium-Ion/Polymer Battery Charger
Thermal Considerations
The AAT3690 is offered in a 3x3mm TDFN package which can provide up to 2.0W of power dissipation when it is properly bonded to a printed circuit board and has a maximum thermal resistance of 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 effect 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. 1: PD = [(VIN - VBAT) * ICC + (VIN * IOP)] Where: TA TJ PD JA = Ambient temperature in degrees C = Maximum device junction temperature below the thermal loop threshold = Total power dissipation by the device = Package thermal resistance in C/W
AAT3690
Example: For an application where the fast charge current for the adapter mode is set to 0.75A, VADP = 5.0V, and the worst case battery voltage is 3.6V, what is the maximum ambient temperature where the thermal limiting will become active? Given: VADP = 5.0V VBAT = 3.6V ICC = 0.75A = 0.75mA = 110C = 50C/W IOP TJ JA
Where: PD VIN = Total power dissipation by the device = Either VADP or VUSB, depending on which mode is selected = Maximum constant fast charge current programmed for the application = Quiescent current consumed by the charger IC for normal operation
Using Equation 3, calculate the device power dissipation for the stated condition: Eq. 3: PD = (5.0V - 3.6V)(0.75A) + (5.0V * 0.75mA)
= 1.05375W
VBAT = Battery voltage as seen at the BAT pin ICC IOP
Next, the maximum operating ambient temperature for a given application can be estimated based on the thermal resistance of the 3x3 TDFN package when sufficiently mounted to a PCB layout and the internal thermal loop temperature threshold. Eq. 2: TA = TJ - (JA * PD)
The maximum ambient temperature before the AAT3690 thermal loop becomes active can now be calculated using Equation 4: Eq. 4: TA = 110C - (50C/W * 1.05375W)
= 57.3125C
Therefore, under the stated conditions for this worst case power dissipation example, the AAT3690 will enter the thermal loop and lower the fast charge constant current when the ambient operating temperature rises above 24.8C.
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3690.2007.01.1.2
1.0A USB Port/Adapter Lithium-Ion/Polymer Battery Charger
Capacitor Selection
Input Capacitor In general, it is good design practice to place a decoupling capacitor between the ADP and USB pins 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 AAT3690 adapter input is to be used in a system with an external power supply source, 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 plugged." 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 AAT3690 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 AAT3690 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.
AAT3690
Printed Circuit Board Layout Considerations
For the best results, it is recommended to physically place the battery pack as close to the AAT3690 BAT pin as possible. To minimize voltage drops on the PCB, keep the high current carrying traces adequately wide. For maximum power dissipation of the AAT3690 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.
ON/OFF J1
123
DS1 (b) BAV74LT1 USB J2 ADP U1
5 1 3 2
GRN LED D2
RED LED D1
0
10 7 8 11 12 4
DS1 (a) BAV74LT1
EN USB ADP BAT TS CT
AAT3690
USB STAT2 STAT1 USBSET ADPSET GND
R5 1.5K
R4 1.5K
BAT TS C1 10F C2 10F C3 10F R3 10K CT C4 0.1F
6 9
R1 8.06K
R2 8.06K
Figure 3: AAT3690 Evaluation Board Schematic.
3690.2007.01.1.2
17
1.0A USB Port/Adapter Lithium-Ion/Polymer Battery Charger
AAT3690
Figure 4: AAT3690 Evaluation Board Top Side Layout.
Figure 5: AAT3690 Evaluation Board Bottom Side Layout.
Component
U1
Part Number
AAT3690IWP-4.2-T1
Description
1.0A USB Port/Adapter Lithium-Ion/ Polymer Battery Charger; 12-Pin 3x3 TDFN Package 8.06K, 1%, 1/4W; 0603 10K, 5%, 1/4W; 0603 1.5K, 5%, 1/4W; 0603 CER 10F 10V 10% X5R 0805 CER 0.1F 16V 10% X7R 0603 Conn. 3-pin Header, 2mm zip 0 Red LED; 1206 Green LED; 1206 Default Diode; SOT23-3
Manufacturer
AnalogicTech
R1, R2 R3 R4, R5 C1, C2, C3 C4 JP1 JP2 D1 D2 DS1 (a, b)
Chip Resistor Chip Resistor Chip Resistor GRM21BR61A106KE19 GRM188R71C104KA01 PRPN401PAEN Chip Resistor CMD15-21SRC/TR8 CMD15-21VGC/TR8 BAV74LT-A
Vishay Vishay Vishay Murata Murata Sullins Electronics Vishay Chicago Miniature Lamp Chicago Miniature Lamp On Semi
Table 3: AAT3690 Evaluation Board Bill of Materials.
18
3690.2007.01.1.2
1.0A USB Port/Adapter Lithium-Ion/Polymer Battery Charger Ordering Information
Package
TDFN33-12
AAT3690
Marking1
RUXYY
Part Number (Tape and Reel)2
AAT3690IWP-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
TDFN33-12
Detail "A" 0.43 0.05
0.1 REF
3.00 0.05 2.40 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. 3690.2007.01.1.2
0.23 0.05
0.23 0.05
0.45 0.05
19
1.0A USB Port/Adapter Lithium-Ion/Polymer Battery Charger
AAT3690
(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. Customers are advised to obtain the latest version of relevant information to verify, before placing orders, that information being relied on is current and complete. All products are sold subject to the terms and conditions of sale supplied at the time of order acknowledgement, including those pertaining to warranty, patent infringement, and limitation of liability. AnalogicTech warrants performance of its semiconductor products to the specifications applicable at the time of sale in accordance with AnalogicTech's standard warranty. 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.
Advanced Analogic Technologies, Inc.
830 E. Arques Avenue, Sunnyvale, CA 94085 Phone (408) 737- 4600 Fax (408) 737- 4611 20
3690.2007.01.1.2

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