AAT3681 USB Port or AC Adapter Lithium-Ion/Polymer Battery Charger General Description Features The AAT3681 BatteryManager is a member of AnalogicTech's Total Power Management ICTM (TPMICTM) product family. This product is an integrated single cell lithium-ion/polymer battery charger IC, designed to operate from a DC power source or USB port up to an input voltage of 6.5V. It requires just one external component. * * * * * * The AAT3681 precisely regulates battery charge voltage and current for 4.2V (4.375V option) lithiumion/polymer battery cells. When charged from an AC adapter or USB port, the battery charging current can be set by an external resistor up to 300mA. * * Battery charge state is continuously monitored for fault conditions. In the event of an over-voltage, short-circuit, or over-temperature failure, the device will automatically shut down, thus protecting the charging device, control system, and the battery under charge. A status monitor output pin is provided to indicate the battery charge status by directly driving an external LED. * * * * BatteryManagerTM USB or AC Adapter System Power Charger -- Programmable from 15mA to 300mA 4.0V ~ 6.5V Input Voltage Range High Level of Integration with Internal: -- Charging Device -- Reverse Blocking Diode Automatic Current Sensing Automatic Recharge Sequencing Full Battery Charge Auto Turn Off/Sleep Mode/Charge Termination Shutdown Current <1A Automatic Trickle Charge for Battery PreConditioning Over-Voltage and Emergency Thermal Protection Power On Reset and Soft Start LED Status Pin 8-Pin 2.0x2.1mm SC70JW Package Applications The AAT3681 is available in a Pb-free, thermally enhanced, space-saving 8-pin 2.0x2.1mm SC70JW package and is specified for operation over the -40C to +85C temperature range. * * * * * * * BluetoothTM Headsets DECT Headsets Digital Still Cameras MP3, Portable Music, and Portable Media Players Personal Data Assistants (PDAs) Wrist Watches Other Lithium-Ion/Polymer Battery-Powered Devices Typical Application Adapter/USB Input BATT+ BAT ADP AAT3681 Enable C BATTBattery Pack STAT EN ISET GND RSET 3681.2006.05.1.1 1 AAT3681 USB Port or AC Adapter Lithium-Ion/Polymer Battery Charger Pin Description Pin # Symbol Type Function 1 EN In 2 ISET In/Out Connect resistor here to set the charge current. 3 BAT In/Out Battery charging and sensing. 4 ADP Power In 5 STAT Out 6, 7, 8 GND Power Enable pin. Logic high enables the IC (internally pulled down). Input from USB/adapter charger. Open drain status pin. Ground connection. Pin Configuration SC70JW-8 (Top View) EN ISET BAT ADP 2 1 8 2 7 3 6 4 5 GND GND GND STAT 3681.2006.05.1.1 AAT3681 USB Port or AC Adapter Lithium-Ion/Polymer Battery Charger Absolute Maximum Ratings1 Symbol VP VN TJ TLEAD Description Value Units -0.3 to 7.5 -0.3 to VP + 0.3 -40 to 150 300 V V C C Description Value Units Maximum Power Dissipation Maximum Thermal Resistance 0.687 160 W C/W ADP Continuous BAT, STAT, ISET, EN Operating Junction Temperature Range Maximum Soldering Temperature (at Leads) Thermal Information2 Symbol PD JA 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. 3681.2006.05.1.1 3 AAT3681 USB Port or AC Adapter Lithium-Ion/Polymer Battery Charger Electrical Characteristics1 VADP = 5V, TA = -25C to +85C, unless otherwise noted. Typical values are TA = 25C. Symbol Description Conditions Min Rising Edge 4.0 3 Operation VADP Adapter Voltage Range Under-Voltage Lockout (UVLO) VUVLO UVLO Hysteresis IOP Operating Current ISHUTDOWN Shutdown Current ILEAKAGE Reverse Leakage Current from BAT Pin Voltage Regulation VBAT_EOC End of Charge Accuracy VCH/VCH Output Charge Voltage Tolerance VMIN Preconditioning Voltage Threshold VRCH Battery Recharge Voltage Threshold Current Regulation ICH Charge Current Programmable Range ICH/ICH Charge Current Regulation Tolerance VSET ISET Pin Voltage KI_A Current Set Factor: ICH/ISET Charging Devices RDS(ON) Charging Transistor On Resistance Logic Control/Protection VEN(H) Input High Threshold VEN(L) Input Low Threshold VSTAT Output Low Voltage ISTAT STAT Pin Current Sink Capability VOVP Over-Voltage Protection Threshold ITK/ICHG Pre-Charge Current ITERM/ICHG Charge Termination Threshold Current Typ 6.5 4 150 0.5 0.3 0.4 Charge Current = 200mA VBAT = 4.25V, EN = GND VBAT = 4V, ADP Pin Open 4.158 2.85 Measured from VBAT_EOC Max Units 4.20 0.5 3.0 -0.1 15 1 1 2 4.242 3.15 0.9 mA % V 1.1 1.6 0.4 0.4 8 STAT Pin Sinks 4mA ICH = 100mA 4.4 10 10 V % V V 300 10 2 800 VADP = 5.5V V V mV mA A A V V V mA V % % 1. The AAT3681 output charge voltage is specified over the 0 to 70C ambient temperature range; operation over the -25C to +85C temperature range is guaranteed by design. 4 3681.2006.05.1.1 AAT3681 USB Port or AC Adapter Lithium-Ion/Polymer Battery Charger Typical Characteristics Charging Current vs. Battery Voltage Constant Charging Current vs. Set Resistor Values 350 1000 RSET = 5.36k 250 100 ICH (mA) ICH (mA) 300 10 RSET = 8.06k 200 150 RSET = 16.2k 100 50 1 0 1 10 100 1000 RSET = 31.6k 2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 VBAT (V) RSET (k ) End of Charge Battery Voltage vs. Supply Voltage End of Charge Voltage Regulation vs. Temperature (RSET = 8.06k ) 4.206 4.23 RSET = 8.06k 4.22 VBAT_EOC (V) VBAT_EOC (V) 4.204 4.202 4.200 RSET = 31.6k 4.198 4.196 4.194 4.21 4.20 4.19 4.18 4.5 4.75 5 5.25 5.5 5.75 6 6.25 4.17 6.5 -50 -25 Constant Charging Current vs. Supply Voltage 50 75 100 (RSET = 8.06k ) 210 220 208 210 205 VBAT = 3.3V ICH (mA) ICH (mA) 25 Constant Charging Current vs. Temperature (RSET = 8.06k ) 200 190 VBAT = 3.6V VBAT = 4V 203 200 198 195 180 170 0 Temperature (C) VIN (V) 193 4 4.25 4.5 4.75 5 5.25 VIN (V) 3681.2006.05.1.1 5.5 5.75 6 6.25 6.5 190 -50 -25 0 25 50 75 100 Temperature (C) 5 AAT3681 USB Port or AC Adapter Lithium-Ion/Polymer Battery Charger Typical Characteristics Operating Supply Current vs. Set Resistor Operating Current vs. Temperature (RSET = 8.06k ) 550 1000 500 IOP (A) IOP (A) VBAT = 3.6V VBAT = 2.85V 100 450 400 350 10 1 10 300 -50 100 -25 RSET (k ) (RSET = 8.06k ) 100 (RSET = 8.06k ) 20.6 ITRICKLE (mA) VMIN (V) 75 20.8 3.02 3.01 3 2.99 20.4 20.2 20.0 19.8 19.6 2.98 19.4 2.97 -50 -25 0 25 50 75 19.2 100 -50 -25 Temperature (C) 35 25 50 75 100 Recharging Threshold Voltage vs. Temperature (RSET = 8.06k ) RSET = 5.36k 30 0 Temperature (C) Preconditioning Charge Current vs. Supply Voltage 4.18 4.16 25 4.14 RSET = 8.06k 20 15 VRCH (V) ITRICKLE (mA) 50 Preconditioning Charge Current vs. Temperature 3.03 RSET = 16.2k 10 4.12 4.10 4.08 4.06 5 4.04 RSET = 31.6k 4 4.25 4.5 4.75 5 5.25 5.5 VIN (V) 6 25 Temperature (C) Preconditioning Threshold Voltage vs. Temperature 0 0 5.75 6 6.25 6.5 4.02 -50 -25 0 25 50 75 100 Temperature (C) 3681.2006.05.1.1 AAT3681 USB Port or AC Adapter Lithium-Ion/Polymer Battery Charger Typical Characteristics VIH_ENABLE vs. Supply Voltage Sleep Mode Current vs. Supply Voltage (RSET = 8.06k ) (RSET = 8.06k ) 800 1.2 700 85C 1.1 VIH_ENABLE (V) ISLEEP (nA) 600 500 400 300 25C 200 -40C -40C 1 0.9 25C 0.8 100 0 85C 0.7 4 4.25 4.5 4.75 5 5.25 5.5 5.75 6 6.25 6.5 VIN (V) 4 4.25 4.5 4.75 5 5.25 5.5 5.75 6 6.25 6.5 VIN (V) VIL_ENABLE vs. Supply Voltage (RSET = 8.06k ) 1.1 -40C VIL_ENABLE (V) 1 0.9 0.8 25C 0.7 85C 0.6 4 4.25 4.5 4.75 5 5.25 5.5 5.75 6 6.25 6.5 VIN (V) 3681.2006.05.1.1 7 AAT3681 USB Port or AC Adapter Lithium-Ion/Polymer Battery Charger Functional Block Diagram Reverse Blocking ADP BAT Current Compare Constant Current ISET STAT Charge Status CV/ Precharge Charge Control UVLO OverTemperature Protection GND EN Functional Description The AAT3681 is a high performance battery charger designed to charge single cell lithium-ion/polymer batteries with up to 300mA of current from an external power source. It is a stand-alone charging solution, with just one external component required for complete functionality. The AAT3681 precisely regulates battery charge voltage and current for 4.2V lithium-ion/polymer battery cells. The adapter/USB charge input constant current level can be programmed up to 300mA for rapid charging applications. The AAT3681 is rated for operation from -40C to +85C. In the event of operating ambient temperatures exceeding the power dissipation abilities of the device package for a given constant current charge level, the charge control will enter into thermal limit. 8 A status monitor output pin is provided to indicate the battery charge state by directly driving one external LED. Device junction 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, protecting the charging device, control system, and the battery under charge. Charging Operation The AAT3681 has four basic modes for the battery charge cycle: pre-conditioning/trickle charge; constant current/fast charge; constant voltage; and end of charge. (See Figure 1.) 3681.2006.05.1.1 AAT3681 USB Port or AC Adapter Lithium-Ion/Polymer Battery Charger Charge Complete Voltage Preconditioning Trickle Charge Phase Constant Current Charge Phase Constant Voltage Charge Phase I = Max CC Regulated Current Constant Current Mode Voltage Threshold Trickle Charge and Termination Threshold I = CC / 10 Figure 1: Current vs. Voltage Profile During Charging Phases. Battery Preconditioning Before the start of charging, the AAT3681 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. When these conditions have been met and a battery is connected to the BAT pin, the AAT3681 checks the state of the battery. If the cell voltage is below the preconditioning voltage threshold (VMIN), the charge control 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 300mA, then the preconditioning mode (trickle charge) current will be 30mA. Cell preconditioning is a safety precaution for deeply discharged battery cells and also aids in limiting power dissipation in the pass transistor when the voltage across the device is at the greatest potential. Constant Current Charging Battery cell preconditioning continues until the voltage on the BAT pin exceeds the preconditioning voltage threshold (VMIN). At this point, the AAT3681 begins the constant current charging phase. The charge constant current (ICH) amplitude is programmed by the user via the RSET resistor. The AAT3681 remains in the constant current charge mode until the battery reaches the voltage regulation point, VBAT. 3681.2006.05.1.1 Constant Voltage Charging The system transitions to a constant voltage charging mode when the battery voltage reaches the output charge regulation threshold (VBAT) during the constant current fast charge phase. The regulation voltage level is factory programmed to 4.2V (0.5%). 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 10% 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 automatically transition into a power-saving sleep mode. Only consuming an ultra-low 0.3A in sleep mode, the AAT3681 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 AAT3681 input voltage drops, the device will enter sleep mode and automatically resume charging once the input supply has recovered from the fault condition. 9 AAT3681 USB Port or AC Adapter Lithium-Ion/Polymer Battery Charger System Operation Flow Chart Enable No Power On Reset Yes Power Input Voltage VIN > VUVLO Yes Shut Down Yes Fault Conditions Monitoring OV, OT Charge Control No Preconditioning Test V MIN > VBAT Yes Preconditioning (Trickle Charge) Yes Constant Current Charge Mode Yes Constant Voltage Charge Mode No No Recharge Test V RCH > VBAT Yes Current Phase Test V IN > VBAT No Voltage Phase Test IBAT > ITERM No Charge Completed 10 3681.2006.05.1.1 AAT3681 USB Port or AC Adapter Lithium-Ion/Polymer Battery Charger Application Information Adapter or USB Power Input Nominal ICHARGE (mA) Set Resistor ) Value (k 300 250 200 150 100 50 40 30 20 15 5.36 6.49 8.06 10.7 16.2 31.6 38.3 53.6 78.7 105 Constant current charge levels up to 300mA may be programmed by the user when powered from a sufficient input power source. The AAT3681 will operate from the adapter input over a 4.0V to 6.5V range. The constant current fast charge current for the adapter input is set by the RSET resistor connected between ISET and ground. Refer to Table 1 for recommended RSET values for a desired constant current charge level. Enable / Disable The AAT3681 provides an enable function to control the charger IC on and off. The enable (EN) pin is internally pulled down. When pulled to a logic high level, AAT3681 is enabled. When left open or pulled to a logic low level, the AAT3681 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 on the BAT pin. Programming Charge Current The fast charge constant current charge level is user programmed with a set resistor placed between the ISET pin and ground. The accuracy of the fast charge, as well as the preconditioning trickle charge current, is dominated by the tolerance of the set resistor used. For this reason, a 1% tolerance metal film resistor is recommended for the set resistor function. Fast charge constant current levels from 15mA to 300mA may be set by selecting the appropriate resistor value from Table 1. 3681.2006.05.1.1 Table 1: RSET Values. 1000 ICH (mA) Adapter Input Charge Inhibit and Resume The AAT3681 has a UVLO and power on reset feature so that if the input supply to the ADP pin drops below the UVLO threshold, the charger will suspend charging and shut down. When power is reapplied to the ADP 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. 100 10 1 1 10 100 1000 RSET (k ) Figure 2: Constant Charging Current vs. Set Resistor Values. 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 overvoltage condition occurs, the AAT3681 charge control will shut down the device until voltage on the BAT pin drops below VOVP. The AAT3681 will resume normal charging operation after the overvoltage condition is removed. Over-Temperature Shutdown The AAT3681 has a thermal protection control circuit which will shut down charging functions should the internal die temperature exceed the preset thermal limit threshold. Once the internal die temperature falls below the thermal limit, normal operation will resume the previous charging state. 11 AAT3681 USB Port or AC Adapter Lithium-Ion/Polymer Battery Charger Charge Status Output The AAT3681 provides battery charge status via a status pin. This pin is internally connected to an Nchannel open drain MOSFET, which can be used to drive an external LED. The status pin can indicate the following conditions: Event Description Status No battery charging activity Battery charging via adapter or USB port Charging completed OFF ON OFF 160C/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: Table 2: LED Status Indicator. The LED should be biased with as little current as necessary to create reasonable illumination; therefore, a ballast resistor should be placed between the LED cathode and the STAT pin. LED current consumption will add to the overall thermal power budget for the device package, hence it is good to keep the LED drive current to a minimum. 2mA should be sufficient to drive most low-cost green or red LED. It is not recommended to exceed 8mA for driving an individual status LED. The required ballast resistor values can be estimated using the following formulas: PD(MAX) = Maximum Power Dissipation (W) JA (5.5V - 2.0V) = 1.75k R1 = 2mA = Package Thermal Resistance (C/W) TJ(MAX) = Maximum Device Junction Temperature (C) [135C] TA = Ambient Temperature (C) Figure 3 shows the relationship of maximum power dissipation and ambient temperature of AAT3681. (VADP - VF(LED)) ILED Example: (TJ(MAX) - TA) JA Where: 1000 800 PD(MAX) (mW) R 1= PD(MAX) = 600 400 200 0 0 20 40 60 80 100 TA (C) Note: Red LED forward voltage (VF) is typically 2.0V @ 2mA. Thermal Considerations The AAT3681 is offered in a SC70JW-8 package which can provide up to 687mW of power dissipation when it is properly bonded to a printed circuit board and has a maximum thermal resistance of 12 Figure 3: Maximum Power Dissipation. Next, the power dissipation can be calculated by the following equation: PD = [(VIN - VBAT) * ICH + (VIN * IOP)] 3681.2006.05.1.1 AAT3681 USB Port or AC Adapter Lithium-Ion/Polymer Battery Charger Where: Capacitor Selection PD Input Capacitor In general, it is good design practice to place a decoupling capacitor between the ADP pin and GND. 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 AAT3681 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 transient effects when the power supply is "hot plugged" in. = Total Power Dissipation by the Device VIN = Input Voltage VBAT = Battery Voltage as Seen at the BAT Pin ICH = Constant Charge Current Programmed for the Application IOP = Quiescent Current Consumed by the Charger IC for Normal Operation [0.5mA] By substitution, we can derive the maximum charge current before reaching the thermal limit condition (thermal cycling). The maximum charge current is the key factor when designing battery charger applications. ICH(MAX) = (PD(MAX) - VIN * IOP) VIN - VBAT (TJ(MAX) - TA) - V * I IN OP JA ICH(MAX) = VIN - VBAT In general, the worst condition is the greatest voltage drop across the charger IC, when battery voltage is charged up to the preconditioning voltage threshold. Figure 4 shows the maximum charge current in different ambient temperatures. 300 ICH(MAX) (mA) Printed Circuit Board Layout Considerations TA = 25C 250 For the best results, it is recommended to physically place the battery pack as close as possible to the AAT3681 BAT pin. To minimize voltage drops on the PCB, keep the high current carrying traces adequately wide. Refer to the AAT3681 evaluation board for a good layout example (see Figures 5 and 6). TA = 45C 200 150 100 TA = 60C TA = 85C 50 0 4.25 4.5 4.75 5 5.25 5.5 5.75 6 6.25 Output Capacitor The AAT3681 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 AAT3681 is to be used in applications where the battery can be removed from the charger, such as with 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. 6.5 6.75 VIN (V) Figure 4: Maximum Charging Current Before Thermal Cycling Becomes Active. 3681.2006.05.1.1 13 AAT3681 USB Port or AC Adapter Lithium-Ion/Polymer Battery Charger Figure 5: AAT3681 Evaluation Board Top Layer. Figure 6: AAT3681 Evaluation Board Bottom Layer. VBAT VIN(ADP) JP2 AAT3681 C1 10F 1 2 3 4 R8 8.06K EN ISET BAT ADP GND GND GND STAT 8 7 6 5 C2 2.2F U1 (SC70JW-8) JP1 0 D1 R1 RED LED 1K Figure 7: AAT3681 Evaluation Board Schematic Diagram. Component Part Number U1 AAT3681IJS-T1 R1 R8 JP1 C1 C2 JP2 LED1 Chip Resistor Chip Resistor Chip Resistor GRM21BR61A106KE19L GRM21BR71A225KA01L PRPN401PAEN CMD15-21SRC/TR8 Description USB/ADP Battery Charger; SC70JW-8 Package 1k, 5%, 1/4W; 0603 8.06k, 1%, 1/4W; 0805 0, 5%, 1/4W; 0603 CER 10F 10V 10% X5R 0805 CER 2.2F 10V 10% X7R 0805 Connecting Header, 2mm Zip Red LED; 1206 Manufacturer AnalogicTech Vishay Vishay Vishay Murata Murata Sullins Electronics Chicago Miniature Lamp Table 3: AAT3681 Evaluation Board Bill of Materials. 14 3681.2006.05.1.1 AAT3681 USB Port or AC Adapter Lithium-Ion/Polymer Battery Charger Ordering Information Package Marking1 Part Number (Tape and Reel)2 SC70JW-8 REXYY AAT3681IJS-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 Information SC70JW-8 2.20 0.20 1.75 0.10 0.50 BSC 0.50 BSC 0.50 BSC 0.225 0.075 2.00 0.20 0.100 7 3 0.45 0.10 4 4 0.05 0.05 0.15 0.05 1.10 MAX 0.85 0.15 0.048REF 2.10 0.30 All dimensions in millimeters. 1. XYY = assembly and date code. 2. Sample stock is generally held on part numbers listed in BOLD. (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 3681.2006.05.1.1 15