AAT3688

USB Port Lithium-Ion/Polymer Battery Charger General Description The AAT3688 BatteryManager™ is a highly integrated single cell lithium-ion/polymer battery charger IC designed to operate with USB port inputs. It requires the minimum number of external components. The AAT3688 precisely regulates battery charge voltage and current for 4.2V lithium-ion/polymer battery cells. Depending on the USB port type, the AAT3688 charge current can be programmed for two separate levels up to 500mA. An optional Charge Reduction Loop is built in to allow users to charge the battery with available current from a USB port, while keeping the port voltage regulated. Battery temperature and charge state are fully monitored for fault conditions. In the event of an over-voltage or over-temperature failure, the device will automatically shut down, thus protecting the charging device, control system, and the battery under charge. Status monitor output pins are provided to indicate the battery charge status by directly driving two external LEDs. A serial interface output is available to report any one of 14 various status states to a microcontroller. The AAT3688 is available in a Pb-free, thermallyenhanced, space-saving 12-pin 3x3mm TDFN package and is rated over the -40°C to +85°C temperature range. AAT3688 Features • • • BatteryManager™ • • • • • • • • • USB Charger — Programmable up to 500mA Max 4.0V to 5.5V Input Voltage Range High Level of Integration With Internal: — Charging Device — Reverse Blocking Diode — Current Sensing Automatic Recharge Sequencing Charge Reduction Loop for USB Charging Battery Temperature Monitoring Full Battery Charge Auto Turn-Off Over-Voltage Protection Emergency Thermal Protection Power On Reset and Soft Start Serial Interface Status Reporting 12-Pin 3x3mm TDFN Package Applications • • • • • • • Bluetooth™ Headsets Cellular Telephones Digital Still Cameras Hand-Held PCs MP3 Players Personal Data Assistants (PDAs) Other Lithium-Ion/Polymer Battery-Powered Devices Typical Application Enable USB Input USB Hi/Lo Select USB USBSEL USBH RSETH RSETL USBL BAT TS C2 10μF EN CHR BATT+ AAT3688 GND BATT- DATA STAT1 STAT2 TEMP Battery Pack Serial Data 3688.2006.10.1.5 1 USB Port Lithium-Ion/Polymer Battery Charger Pin Descriptions Pin # 1 2 3 4 AAT3688 Name USB BAT GND CHR Type In In/Out Ground In/Out Function USB power supply input. Battery charging and sensing. Ground connection. Resistor divider to set USB voltage regulation for charge reduction mode. Leave this pin open for default 4.5V USB regulation point. Tie to USB pin to disable this function. Enable pin. Logic high enables the IC. Connect to 10kΩ NTC thermistor. Status report to microcontroller via serial interface, open-drain. Battery charge status indicator pin to drive an LED: active low, open-drain. Battery charge status indicator pin to drive an LED: active low, open-drain. When USB is present, use this pin to toggle between USBH and USBL charging levels. Connect resistor here to set charge current for low-current USB port. Connect resistor here to set charge current for high-current USB port. Exposed paddle (bottom); connect to GND directly beneath package. 5 6 7 8 9 10 11 12 EP EN TS DATA STAT2 STAT1 USBSEL USBL USBH In In/Out In/Out Out Out In In/Out In/Out Pin Configuration TDFN33-12 (Top View) USB BAT GND CHR EN TS 1 2 3 4 5 6 12 11 10 9 8 7 USBH USBL USBSEL STAT1 STAT2 DATA 2 3688.2006.10.1.5 USB Port Lithium-Ion/Polymer Battery Charger Absolute Maximum Ratings1 Symbol VP VP VN TJ TLEAD AAT3688 Description USB Input Voltage, VBAT Yes Preconditioning Test VMIN > VBAT No Yes Current Phase Test VEOC > VBAT Current Charging Mode Yes Low Current Conditioning Charge USB Voltage Test VUSB < 4.5V No Yes USB Loop Current Reduction in USB Charging Mode No Yes Voltage Charging Mode Voltage Phase Test IBAT > ITERM No Charge Completed 12 3688.2006.10.1.5 USB Port Lithium-Ion/Polymer Battery Charger Application Information USB System Power Charging The USB charge mode provides two programmable fast charge levels up to 500mA for each, USB high and USB low, USBH and USBL, respectively. The USBH or USBL modes may be externally selected by the USB select pin (USBSEL). When the USBSEL pin is connected to a logic high level, the USBH level will be active. Conversely, when USBSEL is pulled to a logic low level (ground), the USBL level will be used for fast charging. Typically USBH is set for 500mA and USBL is set for 100mA. However, these two USB charge levels may be user programmed to any level between 50mA and 500mA by selecting the appropriate resistor values for RSETH and RSETL. Refer to Table 1 for recommended RSETH and RSETL values for the desired USB input constant current charge levels. USB Charge Reduction In many instances, product system designers do not know the real properties of a potential USB port to be used to supply power to the battery charger. Typical powered USB ports commonly found on desktop and notebook PCs should supply up to 500mA. In the event a USB port being used to supply the charger is unable to provide the programmed fast charge current, or if the system under charge must also share supply current with other functions, the AAT3688 will automatically reduce USB fast charge current to maintain port integrity and protect the host system. The USB charge reduction system becomes active when the voltage on the USB input falls below the USB charge reduction threshold (VUSBCHR), which is typically 4.5V. Regardless of which USB charge function is selected (USBH or USBL), the charge reduction system will reduce the fast charge current level in a linear fashion until the voltage sensed on the USB input recovers above the charge reduction threshold voltage. The USB charge reduction threshold (VUSBCHR) may be externally set to a value lower than 4.5V by placing a resistor divider network between VUSB and ground with the center connected to the CHR pin. The USB charge reduction feature may be disabled by connecting a 10kΩ resistor from the CHR pin directly to the USB input pin. The following equation may be used to approximate a USB charge reduction threshold below 4.5V: AAT3688 R12 Eq. 1: VUSBCHR = 2.0V ÷ R12 + R11 where R11/R12 2 PDATA N=1 N=2 N=3 Thermal Considerations The AAT3688 is packaged in a Pb-free, 3x3mm TDFN package which can provide up to 2.0W of power dissipation when it is properly bonded to a printed circuit board and has a maximum thermal resistance of 50°C/W. Many considerations should be taken into account when designing the printed circuit board layout, as well as the placement of the charger IC package in proximity to other heat generating devices in a given application design. The ambient temperature around the charger IC will also have an affect on the thermal limits of a battery charging application. The maximum limits that can be expected for a given ambient condition can be estimated by the following discussion. First, the maximum power dissipation for a given situation should be calculated: Eq. 4: PD = [(VIN - VBAT) · ICC + (VIN · IOP)] Where: PD = Total Power Dissipation by the Device VIN = Input Voltage Level, VUSB VBAT = Battery Voltage as Seen at the BAT Pin ICC IOP = Maximum Constant Fast Charge Current Programmed for the Application = Quiescent Current Consumed by the Charger IC for Normal Operation Next, the maximum operating ambient temperature for a given application can be estimated based on the thermal resistance of the 3x3mm TDFN package when sufficiently mounted to a PCB layout and the internal thermal loop temperature threshold. Eq. 5: TA = TJ - (θJA · PD) 18 3688.2006.10.1.5 USB Port Lithium-Ion/Polymer Battery Charger Where: TA TJ PD = Ambient Temperature in Degrees C = Maximum Device Junction Temperature Protected by the Thermal Limit Control = Total Power Dissipation by the Device AAT3688 Capacitor Selection Input Capacitor In general, it is good design practice to place a decoupling capacitor between the VUSB pin and ground. An input capacitor in the range of 1µF to 22µF is recommended. If the source supply is unregulated, it may be necessary to increase the capacitance to keep the input voltage above the under-voltage lockout threshold during device enable and when battery charging is initiated. If the AAT3688 USB input is to be used in a system with an external power supply source rather than a USB port VBUS, such as a typical AC-to-DC wall adapter, then a CIN capacitor in the range of 10µF should be used. A larger input capacitor in this application will minimize switching or power bounce effects when the power supply is "hot plugged" in. Likewise, a 10µF or greater input capacitor is recommended for the USB input to help buffer the effects of USB source power switching noise and input cable impedance. Output Capacitor The AAT3688 only requires a 1µF ceramic capacitor on the BAT pin to maintain circuit stability. This value should be increased to 10µF or more if the battery connection is made any distance from the charger output. If the AAT3688 is to be used in applications where the battery can be removed from the charger, such as in the case of desktop charging cradles, an output capacitor greater than 10µF may be required to prevent the device from cycling on and off when no battery is present. θJA = Package Thermal Resistance in °C/W Example: For an application where the fast charge current is set to 500mA, VUSB = 5.0V and the worst case battery voltage at 3.0V, what is the maximum ambient temperature at which the thermal limiting will become active? Given: VADP = 5.0V VBAT = 3.0V ICC IOP TJ = 500mA = 0.75mA = 140°C θJA = 50°C/W Using Equation 4, calculate the device power dissipation for the stated condition: Eq. 6: PD = (5.0V - 3.0V)(500mA) + (5.0V · 0.75mA) = 1.00375W The maximum ambient temperature before the AAT3688 thermal limit protection will shut down charging can now be calculated using Equation 5: Eq. 7: TA = 140°C - (50°C/W · 1.00375W) Printed Circuit Board Layout Considerations For the best results, it is recommended to physically place the battery pack as close as possible to the AAT3688 BAT pin. To minimize voltage drops on the PCB, keep the high current carrying traces adequately wide. For maximum power dissipation of the AAT3688 3x3mm TDFN package, the metal substrate should be solder bonded to the board. It is also recommended to maximize the substrate contact to the PCB ground plane layer to further increase local heat dissipation. Refer to the AAT3688 evaluation board for a good layout example (see Figures 5 and 6). = 89.81°C Therefore, under the stated conditions for this worst case power dissipation example, the AAT3688 will suspend charging operations when the ambient operating temperature rises above 89.81°C. 3688.2006.10.1.5 19 USB Port Lithium-Ion/Polymer Battery Charger AAT3688 Evaluation Board Layout AAT3688 Figure 5: AAT3688 Evaluation Board Component Side Layout. Figure 6: AAT3688 Evaluation Board Solder Side Layout. 20 3688.2006.10.1.5 USB Port Lithium-Ion/Polymer Battery Charger AAT3688 Evaluation Board Schematic Diagram ON/OFF J1 Mini-B GND ID D+ DVBUS 5 4 3 2 1 123 AAT3688 USBSEL J2 123 HI LO C2 TB1 USB GND 1 2 RED GRN LED D2 LED D1 R9 R2 R3 Open Open 1 5 10µF R5 10 8 9 7 11 12 U1 USB EN BAT AAT3688 USBSEL STAT2 STAT1 DATA R6 1.5K 1.5K 1.5K BAT TS GND TB2 1 2 3 2 DATA C1 10µF 4 CHR TS GND 3 USBL USBH 6 R8 8.06K R7 42.2K R4 10K R1 Open TDFN33-12 SW1 3688.2006.10.1.5 21 USB Port Lithium-Ion/Polymer Battery Charger AAT3688 Evaluation Board Bill of Materials (BOM) Quantity Description 1 1 1 1 2 1 1 2 1 3 1 1 1 1 AAT3688 Desig. Footprint PAD TBLOK2 TBLOK3 USB-MINI-B 0805 1206LED Manufacturer Mill-Max Phoenix Contact Phoenix Contact Part Number 6821-0-0001-00-00-08-0 277-1274-ND 277-1273-ND Test Pin DATA Connecting Terminal Block, USB,GND 2.54mm, 2 Pos Connecting Terminal Block, BAT, GND, TS 2.54mm, 3 Pos USB 2.0 Receptacle, 5 Pos USB Capacitor, Ceramic, 10µF 6.3V 10% X5R 0805 Typical Red LED, Super Bright Typical Green LED Header, 3-Pin Resistor, 10kΩ 1/16W 5% 0603 SMD Resistor, 1.5kΩ 1/16W 1% 0603 SMD Resistor, 42.2kΩ 1/16W 1% 0603 SMD Resistor, 8.06kΩ 1/16W 1% 0603 SMD Switch Tact 6mm SPST H = 5.0mm AAT3688 USB Port LithiumIon/Polymer Battery Charger C1, C2 D1 D2 J1, J2 R4 R5, R6, R9 R7 R8 SW1 U1 Hirose Electronic H2959CT-ND Co. Ltd. MuRata 490-1717-1-ND CMD15-21SRC/TR8 CMD15-21VGC/TR8 6821-0-0001-00-00-08-0 P10KCFCT-ND P1.5KHTR-ND P42.2KHTR-ND P8.06KHCT-ND CKN9012-ND AAT3688IWP Chicago Miniature Lamp 1206LED Chicago Miniature Lamp HEADER2MM-3 Sullins 0603 Panasonic/ECG 0603 0603 0603 SWITCH TDFN33-12 Panasonic/ECG Panasonic/ECG Panasonic/ECG ITT Industries/ C&K Div. AnalogicTech 22 3688.2006.10.1.5 USB Port Lithium-Ion/Polymer Battery Charger Ordering Information Package TDFN33-12 AAT3688 Marking1 PKXYY Part Number (Tape and Reel)2 AAT3688IWP-4.2-T1 All AnalogicTech products are offered in Pb-free packaging. The term “Pb-free” means semiconductor products that are in compliance with current RoHS standards, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. For more information, please visit our website at http://www.analogictech.com/pbfree. Package Information Index Area (D/2 x E/2) Detail "B" 3.00 ± 0.05 2.40 ± 0.05 0.3 ± 0.10 0.16 0.375 ± 0.125 0.075 ± 0.075 0.1 REF Top View Bottom View Pin 1 Indicator (optional) 7.5° ± 7.5° + 0.05 0.8 -0.20 0.229 ± 0.051 0.05 ± 0.05 Option A: C0.30 (4x) max Chamfered corner Option B: R0.30 (4x) max Round corner Detail "B" Side View All dimensions in millimeters. 1. XYY = assembly and date code. 2. Sample stock is generally held on part numbers listed in BOLD. © Advanced Analogic Technologies, Inc. Detail "A" 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 3688.2006.10.1.5 0.23 ± 0.05 0.45 ± 0.05 Detail "A" 3.00 ± 0.05 1.70 ± 0.05 23