DATA SHEET AAT3620: Single Cell Li+ Switch Mode Battery Charger Applications Description Digital camcorders The BatteryManager™ AAT3620 is an ideal solution for charging high-capacity Li+ batteries. The AAT3620 can supply up to 2.0 A charging current with minimal thermal impact to mobile systems with features such as color display, camera with flash, organizer, video, etc., that requires battery capacity to keep pace with the power requirements. Point of service (POS) Portable DVD players Portable hand-held solutions Portable media players Features Input voltage range: 4.3 to 6.0 V Up to 2.0 A charging current capability 1.5 MHz PWM/linear charger Over 90% full rate charging efficiency Integrated switching device “No BAT” detect Safety timer Integrated sense resistor Built-in reverse blocking feature Battery preconditioning/constant-voltage/constant-current charging mode Programmable end-of-charging current 1% constant-voltage mode regulation Built-in programmable charging timer Charging current indication pin Over-voltage, over-current, and over-temperature protection Battery over-temperature protection The AAT3620 is a pulse-width modulation (PWM) switch mode/linear charger with high charging efficiency at the full constant-current (fast charge) rate. Based on a 1.5 MHz PWM step-down buck converter, the AAT3620 PWM switch mode controls the constant-current charging mode up to 2.0 A, and automatically switches to linear mode charging during the battery conditioning low level current and the light load end-of-charging current termination region. The full charging rate and the end-ofcharging current can be programmed with separate external resistors. A shared charging current indication pin is available for a Coulomb counter. Battery charger temperature and charging state are fully monitored for fault conditions. In the event of an over-current, over-voltage, short-circuit or over-temperature failure, the device automatically shuts down. Two status monitor output pins are provided to indicate the battery charging status and power source status through two display LEDs. The AAT3620 also has a nobattery detection feature, "No BAT", which requires the safety timer. The AAT3620 is available in a thermally enhanced, space-saving 14-pin, 3 mm 3 mm TDFN package. A typical application circuit is shown in Figure 1. The pin configurations are shown in Figure 2. Signal pin assignments and functional pin descriptions are provided in Table 1. Power-on reset and soft-start Space-saving TDFN (14-pin, 3 mm 3 mm) package (MSL1, 260 ºC per JEDEC J-STD-020) Skyworks Green™ products are compliant with all applicable legislation and are halogen-free. For additional information, refer to Skyworks Definition of Green™, document number SQ04-0074. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 201904D • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice • October 21, 2013 1 DATA SHEET • AAT3620 SINGLE CELL LI+ SWITCH MODE BATTERY CHARGER 4.7 μH CS VPIN Adapter LX 100 Ω BATT + VCC 10 μF 0.1 μF Battery Pack BAT 1 μF 22 μF AAT3620 Charge Enable EN BATT PGND VCC CT RT1 0.1 μF TEMP TS RT2 Charging Status 1 STAT 1 Charging Status 2 STAT 2 Charge Current Set Termination Current Set & Charge Current Indicator ISET GND ITERM RTERM RSET tc93 Figure 1. AAT3620 Typical Application Circuit VPIN PGND GND VCC EN ISET CT 1 14 2 13 3 12 4 EP 11 5 10 6 9 7 8 LX CS BAT TS TERM STAT1 STAT2 t0109 Figure 2. AAT3620 Pinout – 14-Pin, 3 mm 3 mm TDFN (Top View) Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 2 October 21, 2013 • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice • 201904D DATA SHEET • AAT3620 SINGLE CELL LI+ SWITCH MODE BATTERY CHARGER Table 1. AAT3620 Signal Descriptions Pin # Name Type Description 1 VPIN In Adapter power input. 2 PGND Ground Power ground. 3 GND Ground Analog ground connection. 4 VCC In Supply Input. 5 EN In Charging enable input, active high, with internal pull-up (to VPIN). 6 ISET In Connect RSET resistor to pin to set constant-current charging current. 7 CT In/Out Timer pin. Connect timing capacitor here for charging timer function. 8 STAT2 Out Battery charging status 2 indicator pin to drive an LED, open-drain. 9 STAT1 Out Battery charging status 1 indicator pin to drive an LED, open-drain. 10 TERM In/Out Connect RTERM resistor to pin to set termination current. Charging current can be monitored with this pin. Leave OPEN to set to 200 mA default termination current. 11 TS In/Out Battery pack temperature sensing input. To disable TS function, pull up to VCC through 10 k resistor. 12 BAT Out Battery positive terminal connecting pin. 13 CS In Return pin for inductor for internal current sensing. 14 LX In/Out Switching node. Ground The exposed thermal pad (EP) must be connected to the board ground plane and pins 2 and 3. The ground plane should include a large exposed copper pad under the package for thermal dissipation (see package outline). EP EP Electrical and Mechanical Specifications The absolute maximum ratings of the AAT3620 are provided in Table 2, the thermal information is listed in Table 3, and electrical specifications are provided in Table 4. Table 2. AAT3620 Absolute Maximum Ratings (Note 1) Maximum Units VPIN, LX Parameter VP Symbol Minimum 0.3 Typical +6.5 V Other pins VN 0.3 VP + 0.3 V Operating junction temperature range TJ 40 + 150 ºC Maximum power dissipation PD 2.5 W Maximum soldering temperature (at leads) TLEAD 300 ºC Note 1: Exposure to maximum rating conditions for extended periods may reduce device reliability. There is no damage to device with only one parameter set at the limit and all other parameters set at or below their nominal value. Exceeding any of the limits listed may result in permanent damage to the device. Table 3. AAT3620 Thermal Information Value Units Maximum thermal resistance (Note 1) Parameter JA Symbol 50 ºC/W Maximum power dissipation (Note 2) PD 2 W Note 1: Mounted on an FR4 board. Note 2: Derate 2.7 mW/C above 25 C ambient temperature. CAUTION: Although this device is designed to be as robust as possible, Electrostatic Discharge (ESD) can damage this device. This device must be protected at all times from ESD. Static charges may easily produce potentials of several kilovolts on the human body or equipment, which can discharge without detection. Industry-standard ESD precautions should be used at all times. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 201904D • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice • October 21, 2013 3 DATA SHEET • AAT3620 SINGLE CELL LI+ SWITCH MODE BATTERY CHARGER Table 4. AAT3620 Electrical Specifications (1 of 2) (Note 1) (VIN = 5.5 V, TA = –25 C to +85C, Unless Otherwise Noted, Typical Values are TA = 25 C) Parameter Symbol Test Condition Min Typical Max Units 6.0 V 4.3 V Operation Adapter input voltage VIN Input under-voltage lockout VCC_UVLO 4.3 VPIN rising 3.5 Hysteresis 150 VBAT + 0.05 V Input sleep voltage VVIN_SLEEP No charging if VVIN < VVIN_SLEEP VBAT + 0.2 mV Operating supply current IVIN_OP EN = high, charging current = 200 mA 5 mA Standby supply current IVIN_STBY EN = high, no charge, power-saving mode 2 mA Shutdown supply current IVIN_SHDN EN = low, LX floating, sleep mode 10 A Forward leakage current, measured from LX to ground IFWD_LKG EN = low, LX = 5.5 V 1 A Reverse leakage current, measured from LX to VIN IREV_LKG EN = low or high, VIN = 0 V, LX = 5.5 V 1 A BAT pin leakage current IBAT_LKG VBAT = 4.2 V, VIN = 0 V or open VIN = 5.5 V Internal PMOS on resistance 1 A 170 300 m RDS(ON) Internal NMOS on resistance PWM switching frequency VIN = 5.5 V fSW VBAT = 3.6 V, ICH_CC = 1 A 120 250 m 1.2 1.5 1.8 MHz 4.158 4.2 4.242 V Charging Regulation Output charging voltage regulation VBAT_REG Charging soft-start delay tSOFT_START Delay of charging from EN, or VCC_UVLO, or VVIN_ADPP Battery conditioning battery voltage threshold VBAT_BC Preconditioning battery charging when VBAT rising: VBAT < VBAT_BC Battery conditioning charging current ICH_BC When VBAT < VBAT_BC Typical battery conditioning charging current setting range ICH_BC_TYP Battery conditioning time- out tCH_BC Stop charging if preconditioning time is more than tCH_BC 15% Constant-current battery charging current accuracy ICH_CC When VBAT_BC < VBAT < VBAT_REG, 1 A to 2 A Fast constant-current charging time out tCH_CCTO Constant voltage charging time-out s 100 2.4 2.6 2.8 0.1 ICH_CC 100 A 200 mA 0.25 CCT +15% Minute/nF 15% ICH_CC +15 % Stop charging if fast charging time is more than tCH_CCFAST 15% 0.022 CCT +15% Hour/nF tCH_CVTO Stop charging if charging time is more than tCH_CV 15% 0.03 CCT +15% Hour/nF Battery recharging voltage threshold VBAT_RCH If VBAT falls below VBAT_RCH, recharging starts VBAT_REG 0.1 V Charging termination threshold current ICH_TERM_TYP Terminate CV charging if ICH < ICH_TERM RTERM 106 A Typical termination threshold current setting range ICH_TERM_RANGE Charger termination current is clamped to the minimum or maximum value if set above or below the ITERM range. 50 200 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 4 V October 21, 2013 • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice • 201904D mA DATA SHEET • AAT3620 SINGLE CELL LI+ SWITCH MODE BATTERY CHARGER Table 4. AAT3620 Electrical Specifications (2 of 2) (Note 1) (VIN = 5.5 V, TA = –25 C to +85C, Unless Otherwise Noted, Typical Values are TA = 25 C) Parameter Symbol Test Condition Min Typical Max Units Logic and Status Input/Output EN input high threshold VIH EN input low threshold VIL 1.6 V 0.4 V EN = VIN 0.1 1 A EN = 0 V 0.6 10 A 1 A 10 mA EN pin supply current IEN STAT1, STAT2 pin leakage current ISLEAK STAT1 and STAT2 pin current sink capability ISTATx STAT pulse width tSTAT_PULSE In fault conditions: CCT = 100 nF 0.5 s STAT pulse frequency fSTAT_FLASH In fault conditions: CCT = 100 nF 1 Hz Battery over-voltage protection threshold VBAT_OVP No charging if VBAT > VBAT_OVP Over-current protection threshold and limit ICL TS hot temperature fault VTS1 When output FET is off Protection VBAT_REG + 0.2 Threshold VTS falling V 2.46 3.0 4.0 A 29.1 30 30.9 % VCC 58.2 60 61.8 % VCC Hysteresis 50 Threshold VTS rising mV TS cold temperature fault threshold VTS2 50 mV Thermal shutdown TSD 140 ºC Thermal shutdown hysteresis TSD_HYS 15 ºC Hysteresis Note 1: Performance is guaranteed only under the conditions listed in this Table. Typical Performance Characteristics 2400 2250 2100 2000 Fast Charge Current (mA) Charging Current (mA) Typical performance characteristics of the AAT3620 are illustrated in Figures 3 through 10. 1800 1500 1200 900 –25 °C 25 °C 85 °C 600 300 1750 1500 1250 1000 750 500 250 0 0 2.2 2.5 2.8 3.1 3.4 3.7 4.0 Battery Voltage (V) Figure 3. Charging Current vs Battery Voltage 4.3 10 30 50 70 90 110 ISET Resistor (kΩ) Figure 4. Constant-Current Charging Mode Current vs ISET Resistor (VIN = 5 V, VBAT = 3.5 V) Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 201904D • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice • October 21, 2013 5 DATA SHEET • AAT3620 SINGLE CELL LI+ SWITCH MODE BATTERY CHARGER 4.080 62 60 End of Charging Voltage (V) Termination Current (mA) 64 58 56 54 52 50 48 46 44 42 40 4.075 4.070 4.065 4.060 4.055 4.050 -40 -15 10 35 60 -40 85 -15 10 Figure 5. Termination Current vs Temperature (VIN = 5 V, RTERM = 49.9 k) 3.0 Shutdown Current (μA) 2.63 2.62 2.61 2.60 2.59 2.58 2.57 2.56 -40 2.5 2.0 1.5 1.0 –25 °C 25 °C 85 °C 0.5 0.0 -15 10 35 60 85 4.5 5.0 Temperature (°C) 5.5 6.0 Input Voltage (V) Figure 7. Preconditioning Rising Threshold Voltage vs Temperature (VIN = 5.5 V) Figure 8. Shutdown Current vs Input Voltage 2400 2500 2100 2000 Charge Current (mA) 1800 1500 1200 900 VBAT = 2.7 V VBAT = 3.3 V VBAT = 3.6 V VBAT = 3.9 V 600 300 0 4.0 1500 1000 VBAT = 2.7 V VBAT = 3.3 V VBAT = 3.6 V VBAT = 3.9 V 500 0 4.2 4.4 4.6 4.8 5.0 5.2 5.4 5.6 5.8 6.0 Input Voltage (V) Figure 9. Charging Current vs Input Voltage (T = 25 °C) 4.0 4.5 5.0 5.5 6.0 6.5 Input Voltage (V) Figure 10. Charging Current vs Input Voltage (T = 85 °C) Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 6 85 Figure 6. Recharging Voltage vs Temperature (VIN = 5 V) 2.64 Preconditioning Rising Threshold Voltage (V) 60 Temperature (°C) Temperature (°C) Battery Charging Current (mA) 35 October 21, 2013 • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice • 201904D DATA SHEET • AAT3620 SINGLE CELL LI+ SWITCH MODE BATTERY CHARGER PGND Reverse Blocking VPIN LX Reverse Blocking CS VCC Volt Det / UVLO BAT EN PWM / Linear Charge Control GND VREF TS Over-Temperature Protection ISET TERM CT Charge status STAT1 Current Set STAT2 Timer t0119 Figure 11. AAT3620 Functional Block Diagram Functional Description Linear Charging Control Loop Linear charging current relationship: The AAT3620 uses an average current mode step-down converter to implement the DC-DC switch-mode converter function during constant-current mode charging. The technique of average current mode control overcomes peak current control problems by introducing a high gain integrating current error amplifier into the current loop. Average current tracks the sensed output current with a high degree of accuracy and excellent noise immunity. The oscillator sawtooth ramp provides compensation so no slope compensation is required for duty cycle exceeding 50%. The high gain of the current error amplifier at DC accurately programs the output. The switching charger works in continuous current mode PWM only. There is a soft start before entering constant-current charging mode and the charger re-enters linear operation in constant voltage mode when the charging current drops below 300 mA. A functional block diagram is shown in Figure 11. Linear vs Switching Battery Charging The AAT3620 performs battery charging using the benefits of the step-down or buck architecture to multiply the input current when stepping down the output voltage. This property maximizes battery charging from current limited devices and greatly decreases power and heat-related dissipation. The process is expressed mathematically in the following comparison: I BATL I IN Efficiency of linear charger: VBAT VIN Switch-Mode Charging Switch-mode current relationship: I BATS S VIN I IN VBAT Where: s = 90%. Example: Power Savings Conventional linear charger IC: PD VIN VBAT I BAT 5 3.5 0.5 0.75W Switch-mode charger IC: PD V BAT I BAT V BAT I BAT 3.5 0.5 3.5 0.5 0.194W 0.9 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 201904D • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice • October 21, 2013 7 DATA SHEET • AAT3620 SINGLE CELL LI+ SWITCH MODE BATTERY CHARGER Adapter Input Charging Inhibit and Resume The AAT3620 checks the condition of the battery and determines which charging mode to apply. If the battery voltage is below VBAT_BC, the AAT3620 begins battery conditioning until the battery voltage reaches VBAT_BC. The battery conditioning current is 10% of constant-current level. Once the AAT3620 reaches VBAT_BC, it begins constant-current mode charging. The constant-current mode current level is programmed using a single resistor from the ISET pin to ground. Programmed current can be set from a minimum of 1 A to a maximum of 2 A. Constant-current charging continues until the battery voltage reaches the voltage regulation point VBAT_REG. When the battery voltage reaches VBAT_REG, the AAT3620 transitions to constantvoltage mode. The regulation voltage is factory programmed to a nominal 4.2 V and continues charging until the charging current is reduced to the termination current programmed by the resistor connected from ITERM to ground. The termination current program range is 50 to 200 mA. The AAT3620 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 suspends charging and shuts down. When power is re-applied to the IN pin or the UVLO condition recovers, the system charging control assesses the state of charging on the battery cell and automatically resumes charging in the appropriate mode for the condition of the battery. Input/Output Capacitor and Inductor The AAT3620 contains a high-performance 2 A, 1.5 MHz synchronous step-down converter. The step-down converter operates to ensure high efficiency performance over all load conditions. It requires only 3 external power components (CIN, COUT, and L). Apart from the input capacitor, only a small L-C filter is required at the output side for the step-down converter to operate properly. Typically, a 4.7 H inductor such as the Wurth 7447789004 and a 22 F to 47 F ceramic output capacitor is recommended for low output voltage ripple and small component size. Ceramic capacitors with X5R or X7R dielectrics are highly recommended because of their low ESR and small temperature coefficients. A 10 F ceramic input capacitor is sufficient for most applications. After the charging cycle is complete, the AAT3620, turns off the series pass device and automatically goes into a power saving mode. During this time, the series pass device blocks current in both directions, preventing the battery from discharging through the IC. The AAT3620 shuts down if the charger source is disconnected until the charging source is reconnected and VIN is greater than the VIN_SLEEP threshold. Battery Charging Figure 12 illustrates the entire battery charging profile, which consists of three phases: Battery charging starts only after the AAT3620 checks several conditions to maintain a safe charging environment. The input supply must be above the minimum operating voltage (UVLO) and above the battery voltage by 0.3 V, the battery temperature must be within the 0 °C ~ 45 °C range, and the enable pin must be high. V Charging Complete Regulated Voltage 4.2 Preconditioning Trickle Constant-Current Charging Fast Charging Phase Phase 1 1. Preconditioning-current mode (trickle) charging 2. Constant-current mode charging 3. Constant-voltage mode charging Constant-Voltage Taper Charging Phase 3 2 Constant-Current I Charging Phase Constant-Voltage Battery Discharging Taper Charging Phase Battery Recharging Voltage Threshold 3 2 Regulated Current 1C Constant-Current Mode Voltage Threshold 2.6 300 mA Trickle Charging and Termination Threshold (Programmable) L S L S L Time The profile consists of three phases: 1. Preconditioning-Current Mode (Trickle) Charging - Linear Mode 2. Constant-Current (Fast) Mode Charging - Switching Mode 3. Constant-Voltage Mode (Taper) Charging - Switching/Linear Mode. Figure 12. Charging Current and Battery Voltage vs Time Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 8 October 21, 2013 • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice • 201904D t0220 DATA SHEET • AAT3620 SINGLE CELL LI+ SWITCH MODE BATTERY CHARGER The battery preconditioning current is equal to 10% of the constant-current charging level, so the battery preconditioning current range is 100 to 200 mA. Linear mode is on standby while switch-mode is active in the constant-current charging region 2.6 V < VBAT < 4.2 V. The charger re-enters linear mode while in constant voltage mode after the switch-mode current drops below 300 mA. The termination current is programmed by an external resistor with a separate ITERM pin and the termination current set pin also monitors the charging current. The output short circuit current is equal to the battery preconditioning current. Preconditioning Trickle Charge Battery charging starts only after the AAT3620 battery charger checks several conditions in order to maintain a safe charging environment. The system operation flow chart for the battery charger operation is shown in Figure 13. The input supply must be above the minimum operating voltage (UVLO) and the enable pin (EN) must be high (it is internally pulled up). When the battery is connected to the BAT pin, the battery charger checks the condition of the battery and determines which charging mode to apply. Preconditioning – Current Mode Charging Current If the battery voltage is below the preconditioning voltage threshold VCH_BC, the battery charger initiates precondition trickle charging mode and charges the battery at 10% of the programmed constant-current magnitude. For example, if the programmed current is 1 A, the trickle charging current would be 100 mA. Trickle charging is a safety precaution for a deeply discharged cell. It also reduces the power dissipation in the internal series pass MOSFET when the input-output voltage differential is at its highest. Constant – Current Mode Charging Current Trickle charging continues until the battery voltage reaches VBAT_BC. At this point the battery charger begins constantcurrent charging. The current level default for this mode is programmed using a resistor from the ISET pin to ground. Programmed current can be set at a minimum of 100 mA and up to a maximum of 2.0 A. The AAT3620 contains a high performance 2 A, 1.5 MHz synchronous step-down converter. The step-down converter operates to ensure high efficiency performance over all load conditions. It requires only 3 external power components (CIN, COUT, and L). Constant – Voltage Mode Charging Constant-current charging continues until the battery voltage reaches the output charging voltage regulation point VBAT_REG. When the battery voltage reaches VBAT_REG, the battery charger transitions to constant-voltage mode. VBAT_REG is factory programmed to 4.2 V (nominal). Charging in constant-voltage mode continues until the charging current is reduced to the programmed end-of-charging termination current. Power-Save Mode After the charging cycle is complete, the battery charger turns off the series pass device and automatically goes into powersave mode. During this time, the series pass device blocks current in both directions to prevent the battery from discharging through the battery charger. In power-save mode, the battery charger monitors all parameters and resumes charging in the most appropriate mode. Sleep Mode The battery charger shuts down if the charger source is disconnected and VIN is less than VIN_SLEEP threshold. It comes out of sleep mode if either VIN is greater than VIN_SLEEP or EN pin is cycled high while VIN is greater than VIN_SLEEP. Programming Charging Current (ISET) The default constant-current mode charging level is userprogrammed with a set resistor placed between the ISET pin and ground. The accuracy of the constant charging current, as well as the preconditioning trickle charging current, is dominated by the tolerance of the set resistor. For this reason, a 1% tolerance metal film resistor is recommended for the set resistor function. The constant charging current levels from 1 to 2 A can be set by selecting the appropriate resistor value from Table 5. Table 5. ISET Resistor vs Constant-Current Mode Current RSET (k) ICH_CC (mA) 100 2000 90 1800 80 1600 70 1400 60 1200 50 1000 40 800 30 600 20 400 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 201904D • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice • October 21, 2013 9 DATA SHEET • AAT3620 SINGLE CELL LI+ SWITCH MODE BATTERY CHARGER Enable No Power On Reset Yes No Power Input Voltage VCC > VCC_UVLO Expired Yes Yes Shut Down Fault Conditions Monitoring OV, OT, VTS1<TS<VTS2 Charging Timer Control No Preconditioning Test Yes Preconditioning (Trickle Charge) VBAT<VBAT_BC VBAT > VBAT_BC No No Recharging Test VBAT_RCH > VBAT Yes Current Phase Test VBAT<VBAT_REG Yes Constant Current Charging Mode VBAT > VBAT_REG No Voltage Phase Test IBAT>ICH_TERM Yes Constant Voltage Charging Mode IBAT < ICH_TERM No Charging Completed t0221 Figure 13. System Operation Flowchart for the Battery Charger Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 10 October 21, 2013 • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice • 201904D DATA SHEET • AAT3620 SINGLE CELL LI+ SWITCH MODE BATTERY CHARGER Programmable Charging Termination Current The charging termination current ICH_TERM can be programmed by connecting a resistor from TERM to GND: I CH_TERM RTERM 10 6 If the TERM pin is left open, the termination current level is set to 200 mA as the default. When the charging current drops to the termination current level, the device terminates charging and goes into a powersave mode. The charger remains in this mode until the battery voltage decreases to a level below the battery recharging voltage threshold (VBAT_RCH). Consuming very low current in the power-save mode, the AAT3620 minimizes battery drain when it is not charging. This feature is particularly useful in applications where the input supply level can fall below the battery charge. If the AAT3620 input voltage drops, the device enters sleep mode and automatically resumes charging once the input supply has recovered from the fault condition. The TERM pin can also be used as a charging current monitor when the charging current voltage level = 1 A/V. Status Indicator (STAT1/STAT2) Charging Status Output The AAT3620 provides battery charger status using two status pins (STAT1 and STAT2). Each of the two pins is internally connected to an N-channel open-drain MOSFET. The status pin can indicate the conditions shown in Table 6. 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 cathode and the STAT pins. LED current consumption adds to the overall thermal power budget for the device package, so keeping the LED drive current to a minimum is recommended – 2 mA should be sufficient to drive most low-cost green or red LEDs. Do not exceed 8 mA for driving an individual status LED. The required ballast resistor values can be estimated using the following equation: RBALLSAT VIN VF ( LED ) I LED Example: RBALLSAT 5.0V 2.0V 1.5k 2mA Note: red LED forward voltage (VF) is typically 2.0 V @ 2 mA. Protection Circuitry Charging Safety Timer (CT) While monitoring the charging cycle, the AAT3620 utilizes a charging safety timer to help identify damaged cells and to ensure that the cell is charged safely: Upon initiating a charging cycle, the AAT3620 charges the cell at 10% of the programmed maximum charging until VBAT > 2.6 V. If the cell voltage fails to reach the precondition threshold of 2.6 V (typical) before the safety timer expires, the cell is assumed to be damaged and the charging cycle terminates. If the cell voltage exceeds 2.6 V prior to the expiration of the timer, the charging cycle proceeds into fast charging. There are three time-out periods, as shown in Table 7. Table 6. LED Status Indicator STAT1 and STAT2 Conditions STAT1 STAT2 ON ON Fast-charging ON OFF End-of-charging (charging complete) OFF ON Charging disabled OFF OFF Pre-charging Sleep mode (VIN < VIN_SLEEP) OFF OFF FLASH, 50% duty cycle FLASH, 50% duty cycle Fault condition (battery 0 V) OFF OFF Fault condition [battery OT (over-temperature) / UT (under-temperature)] OFF OFF Fault condition (device OT) OFF OFF Fault (pre-charging time out) OFF FLASH, 50% duty cycle Fault (time out) OFF OFF No battery with charging enabled Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 201904D • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice • October 21, 2013 11 DATA SHEET • AAT3620 SINGLE CELL LI+ SWITCH MODE BATTERY CHARGER Table 7. Summary for a 0.1 F Ceramic Capacitor Used for the Timing Capacitor Mode Time Trickle charging (TC) time-out 25 minutes Trickle charging (TC) + constant-current (CC) mode time-out 2.2 hours Constant-voltage (CV) mode time-out 3 hours The AAT3620 has a battery fault detector, which, when used in conjunction with a 0.1 F capacitor on the CT pin, outputs a 1 Hz signal with 50% duty cycle at the STAT2 pin in the event of a time-out while in trickle charging mode. The CT pin is driven by a constant-current source and provides a linear response to increase the timing capacitor value. Thus, if the timing capacitor is doubled from the nominal 0.1 F value, the time-out periods are doubled. The CT pin should not be left floating or unterminated, as this would cause errors in the internal timing control circuit. The constant-current provided to charge the timing capacitor is very small, so 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 close as possible to the CT pin. Because the accuracy of the internal timer is dominated by the capacitance value, a ceramic capacitor with 10% tolerance or better is recommended. The X7R and X5R types of ceramic capacitors are good choices for this application. The AAT3620 has the no-battery detection function, "No-BAT". The CT pin capacitor (CCT) sets up an internal clock to reset the no battery detector every 8 clock periods. The internal clock frequency is inversely proportional to the CCT: f 100 nF Hz CCT The no-battery detection function detects when the charger toggles between charging termination and the recharging threshold in less than 8 clock periods. If this occurs for four consecutive times, the battery is considered disconnected. Requiring four consecutive "No BAT" cycles prevents a false indication when the battery connection is bounced. If the battery is disconnected while powered on, the recommended 0.1 F capacitor at CT pin creates a 1 Hz internal clock to make the STAT LED blink at 1 Hz, 50% duty cycle, to indicate “no battery connected.” To ensure that the charger cycles between charging termination and recharging in less than 8 clock periods, the BAT pin capacitor cannot exceed 22 F for every 100 nF on the CT pin. For example, if CCT is 220 nF, the capacitor on the BAT pin cannot exceed 47 F. If more capacitance is used on the BAT pin, it takes longer than 8 clock periods to complete a charge termination/recharging cycle and the no-battery detection does not work. Note that disabling the safety timer (CT pin grounded) on the AAT3620 leads to a false "No BAT" detection, and both STAT pins go low after four consecutive charge termination/recharge cycles. Over-Voltage Protection An over-voltage event is defined as a condition where the voltage on the BAT pin exceeds the maximum battery charging voltage and is set by the over-voltage protection threshold (VBAT_OVP). If an over-voltage condition occurs, the AAT3620 charging control shuts down the device until the voltage on the BAT pin drops below VBAT_OVP. The AAT3620 resumes normal charging operation after the over-voltage condition is removed. During an over-voltage event, the STAT LEDs report a system fault. Over-Temperature Shutdown The AAT3620 has a thermal protection control circuit which shuts down charging functions if the internal die temperature exceeds the preset thermal limit threshold. When the internal die temperature falls back below the thermal limit, normal operation resumes the previous charging state. Battery Temperature Fault Monitoring (TS) In the event of a battery over-temperature condition, the charging control turns off the internal pass device and reports a battery temperature fault on the STAT pins. After the system recovers from a temperature fault, the device resumes charging operation. The AAT3620 checks battery temperature before starting the charging cycle, as well as during all stages of charging. This is accomplished by monitoring the voltage at the TS pin. The internal battery temperature sensing system (Figure 14) is comprised of two comparators that establish a voltage window for safe operation. The thresholds for the TS operating window are bounded by the VTS1 and VTS2 specifications. Refer to the electrical characteristics in Table 4: VTS1 threshold = 0.30 VCC and the VTS2 threshold = 0.60 VCC. This system is intended for use with negative temperature coefficient thermistors (NTC), which are typically integrated into the battery package. Most of the commonly used NTC thermistors in battery packs are approximately 10 k at room temperature (25 °C). If the battery gets too hot during charging due to an internal fault or excessive constant charging current, the thermistor heats up and reduces in value, pulling the TS pin voltage lower than the TS1 threshold, and the AAT3620 stops charging until the condition is removed, when charging is resumed. To accurately set the TS voltage according to the temperature coefficient and the nominal value of the thermistor, two resistors can be used as shown in the example below. It is recommended to use NTC thermistors in the 10 k to 100 k range, with Beta constant values in the 3000 to 5000 range. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 12 October 21, 2013 • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice • 201904D DATA SHEET • AAT3620 SINGLE CELL LI+ SWITCH MODE BATTERY CHARGER 1 1 RNTC ( HOT ) RNTC ( COLD ) Ratio Cold Ratio Hot RT2 1 1 1 RNTC ( COLD ) 1 RNTC ( HOT ) Ratio Hot Ratio Cold 1 Ratio Cold RT 2 R NTC ( COLD ) RT1 Ratio Cold RT 2 R NTC ( COLD ) Where: Ratio Cold = 0.60 (2% tolerance) The AAT3620 is offered in a TDFN33-14 package which can provide up to 2 W of power dissipation when properly bonded to a printed circuit board. The maximum thermal resistance is 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 also has 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 considerations: 1. The maximum power dissipation for a given situation should be calculated: Ratio Hot = 0.30 (2% tolerance) RNTC(COLD) = Thermistor resistance at Cold (typically 0 °C) p D(MAX) RNTC(HOT) = Thermistor resistance at Hot (typically 45 °C) For a 10 k NTC thermistor with a Beta of 3370: TJ ( MAX ) TA JA RNTC(0C) = 28.1 k Where: RNTC(45C) = 4.91 k PD(MAX) = maximum power dissipation (W) The calculation results are as follows: JA = package thermal resistance (°C/W) RT2 = 31.6 k TJ(MAX) = maximum device thermal shutdown temperature (°C) [140 °C] RT1 = 9.92 k If the use of the TS pin function is not required by the system, it should be tied to VCC using a 10 k resistor. TA = ambient temperature (°C) 2. The power dissipation for both the linear charging mode and the switching charger mode should be considered. VCC The power dissipation for the switching charger can be calculated by the following equation: VCC 0.6 VCC RT1 p D(MAX) VPIN Battery Cold Fault TS RT2 2 I CH _ CC RDS ( ON ) HS VBAT RDS ( ON ) LS VPIN VBAT t SW f SW I CH _ CC I QOP VPIN Battery Pack Battery Hot Fault RNTC Where: PD(MAX) = total power dissipation by the device 0.3 VCC VPIN = adapter input voltage VBAT = battery voltage at the BAT pin t0221 Figure 14. AAT3620 Battery Temperature Sense Circuit Thermal Considerations The actual maximum charging current is a function of Charging Adapter input voltage, the state of the battery charging at the moment of charging, the system supply current from the BAT pin, the ambient temperature and the thermal impedance of the package. The maximum programmable current may not be achievable under all operating parameters. ICH_CC = constant charging current programmed for the application IQOP = quiescent current consumed by the IC for normal operation [5 mA] RDS(ON)HS and RDS(ON)LS = on-resistance of step-down high and low side MOSFETs 3. The power dissipation for the linear charging mode can be calculated by the following equation: p D(MAX) VPIN VBAT I CH _ BC VPIN I QOP Where: Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 201904D • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice • October 21, 2013 13 DATA SHEET • AAT3620 SINGLE CELL LI+ SWITCH MODE BATTERY CHARGER PD(MAX) = total power dissipation by the device For the linear mode: VPIN = input voltage IQOP = 0.005 A VPIN = 6 V VBAT = 2 V ICH_BC = 0.2 A VBAT = battery voltage as seen at the BAT pin ICH_BC = battery conditioning charging current programmed for the application IQOP = quiescent current consumed by the charger IC for normal operation [5 mA]. By substitution, the maximum charging current before reaching the thermal limit condition (thermal loop) can be derived. The maximum charging current is the key factor when designing battery charger applications: I CH_BC(MAX) PD( MAX ) VPIN I QOP VPIN VBAT TJ T A I CH(MAX) JA VPIN I QOP 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 and entering ConstantCurrent (CC) switching charging mode. Example Worst-Case Power Dissipation The worst-case power dissipation can be calculated using the lowest battery voltage level when the charger enters CC charging mode and the charging current is set to 2 A: ICH_CC = 2 A VPIN =6 V RDS(ON)HS = 0.3 RDS(ON)LS = 0.25 tSW = 5 10-9 IQOP = 0.005 A fSW = 1.5 106 TA = 85 °C JA = 50 °C/W p D(MAX) PCB Layout Guidance When laying out the PC board, follow the guidelines below to ensure proper operation of the AAT3620: Solder the exposed pad EP reliably to PGND/AGND and multilayer GND. Connect the exposed thermal pad to board ground plane and pins 2 and 3. Include a large exposed copper pad under the package in the ground plane with vias to all board layers for thermal dissipation. Keep the power traces, including GND traces, the LX traces and the VIN trace short, direct and wide to allow large current flow. Make the L1 connection to the LX and CS pins as short as possible. Use several via pads when routing between layers. Connect the input capacitors (C1, C4, and C5) as close as possible to VPIN (pin 1), VCC (pin 4) and GND/PGND (pins 2, 3) to get good power filtering. It is recommended to add a resistor R7 between VIN and VCC to create a low-pass RC filter on VCC. Keep the resistance of the trace from the load return to the PGND (pin 2) to a minimum. This helps to minimize any error in DC regulation due to differences in the potential of the internal signal ground and the power ground. 6V p D(MAX) 0.83W Connect the output capacitors C2, C6 and C7 and inductor L1 as close as possible, and do not route any signal lines under the inductor. 2 A2 0.3 2.8V 0.25 6V 2.8V 5 10 p D(MAX) 6V 2V 0.2 A 6V 0.005 A 9 1.5 10 2 A 0.005 A 6V p D(MAX) 1.213W TJ(MAX) 85 50 1.213( C ) 6 Evaluation Board Description The AAT3620 Evaluation Board is used to test the performance of the AAT3620. An Evaluation Board schematic diagram is provided in Figure 15. Layer details for the Evaluation Board are shown in Figure 16. The Evaluation Board has additional components for easy evaluation; the actual bill of materials required for the system is shown in Table 8. TJ(MAX) 145.65( C ) Package Information Package dimensions for the 14-pin TDFN33 package are shown in Figure 17. Tape and reel dimensions are shown in Figure 18. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 14 October 21, 2013 • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice • 201904D DATA SHEET • AAT3620 SINGLE CELL LI+ SWITCH MODE BATTERY CHARGER C5 1 μF C1 0.1 μF TP5 CS C6 0.1 μF TB2 GND VIN TP2 100 Ω R7 VCC TP1 U1 AAT3620-TDFN33-14 1 VIN C4 10 μF 2 3 TP3 4 JP1 GND 5 R4 EN 6 100 kΩ L1 4.7 μH 7 VPIN LX PGND CS GND BAT VCC TS EN TERM ISET STAT1 CT STAT2 EP VCC TP4 14 TP8 R1 10 kΩ BAT LX 13 TB1 12 C7 11 10 9 8 C3 0.1 μF BAT GND TS C2 0.1 μF 22 μF R3 49.9 kΩ R5 2 kΩ D1 R6 2 kΩ TS VIN STAT1 D2 JP2 TS TP7 R2 10 kΩ TP6 GND STAT2 tc94 Figure 15. AAT3620 Evaluation Board Schematic Table 8. AAT3620 Evaluation Board Bill of Materials Component Description Value Footprint C4 Capacitor, Ceramic, X5R, 10 V, ±20% 10 F 0805 C1, C3, C6, C7 Capacitor, Ceramic, 20%, 10 V, X5R 0.1 F 0603 C2 Capacitor, Ceramic, 20%, 10 V, X5R 22 F 1206 C5 Capacitor, Ceramic, 20%, 10 V, X5R 1 F 0603 L1 Inductor, Wurth, 7447789004 4.7 H 7 mm 7 mm R1, R2 Resistor, 5% 10 k 0402 R5, R6 Resistor, 5% 2 k 0402 R3 Resistor, 1% 49.9 k 0402 R4 Resistor, 1% 100 k 0402 R7 Resistor, 1% 100 0402 D1, D2 Red and green SMD (a) Top Layer 0402 (b) Bottom Layer tc95 Figure 16. AAT3620 Evaluation Board Layer Details Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 201904D • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice • October 21, 2013 15 DATA SHEET • AAT3620 SINGLE CELL LI+ SWITCH MODE BATTERY CHARGER Detail "A" 3.000 ± 0.050 2.500 ± 0.050 Index Area 1.650 ± 0.050 3.000 ± 0.050 Top View Bottom View + 0.100 - 0.000 0.400 BSC 0.000 0.203 REF 0.750 ± 0.050 0.425 ± 0.050 Pin 1 Indicator (Optional) 0.180 ± 0.050 Side View Detail "A" All dimensions are in millimeters. t0060 Figure 17. AAT3620 14-pin TDFN Package Dimensions 4.00 ± 0.00 1.75 ± 0.10 2.00 ± 0.05 5.50 ± 0.05 1.50 ± 0.10 12.00 ± 0.30 1.10 ± 0.00 3.30 ± 0.10 Pin 1 Location 0.30 ± 0.05 3.30 ± 0.10 8.00 ± 0.10 All dimensions are in millimeters t0059 Figure 18. AAT3620 Tape and Reel Dimensions Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 16 October 21, 2013 • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice • 201904D DATA SHEET • AAT3620 SINGLE CELL LI+ SWITCH MODE BATTERY CHARGER Ordering Information Model Name AAT3620 Single Cell Li+ Switch Mode Battery Charger Part Marking (Note 2) 6WXYY Manufacturing Part Number (Note 1) AAT3620IWO-4.2-T1 Evaluation Board Part Number AAT3620IWO-4.2-EVB Note 1: XYY = assembly and date code. Note 2: Sample stock is generally held on part numbers listed in BOLD. Copyright © 2012-2013 Skyworks Solutions, Inc. All Rights Reserved. Information in this document is provided in connection with Skyworks Solutions, Inc. (“Skyworks”) products or services. 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Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 201904D • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice • October 21, 2013 17