AAT2557 500mA Battery Charger and 300mA LDO Regulator for Portable Systems General Description Features The AAT2557 is a fully integrated 500mA battery charger and a 300mA low dropout (LDO) linear regulator. The input voltage range is 4V to 6.5V for the battery charger and 2.7V to 5.5V for the linear regulator, making it ideal for applications operating with single-cell lithium-ion/polymer batteries. • The battery charger is a complete constant current/constant voltage linear charger. It offers an integrated pass device, reverse blocking protection, high accuracy current and voltage regulation, charge status, and charge termination. The charging current is programmable via external resistor from 15mA to 500mA. In addition to these standard features, the device offers over-voltage, current limit, and thermal protection. • • • • The linear regulator is designed for fast transient response and good power supply ripple rejection. Capable of up to 300mA load current, it includes short-circuit protection and thermal shutdown. SystemPower™ Battery Charger: — Input Voltage Range: 4V to 6.5V — Programmable Charging Current up to 500mA — Highly Integrated Battery Charger • Charging Device • Reverse Blocking Diode Linear Regulator: — 300mA Output Current — Low Dropout: 400mV at 300mA — Fast Line and Load Transient Response — High Accuracy: ±1.5% — 70µA Quiescent Current Short-Circuit, Over-Temperature, and Current Limit Protection TSOPJW-14 Package -40°C to +85°C Temperature Range Applications The AAT2557 is available in a Pb-free, thermallyenhanced TSOPJW-14 package and is rated over the -40°C to +85°C temperature range. • • • • • • Bluetooth® Headsets Cellular and DECT Phones Handheld Instruments MP3 and Portable Music Players PDAs and Handheld Computers Portable Media Players Typical Application Adapter/USB Input ADP INLDO STAT Charger Enable C INLDO EN_BAT BATT+ BAT ENLDO VOUTLDO C BAT OUTLDO C OUTLDO ISET BYP C BYP System AAT2557 LDO Enable GND BATTRSET Battery Pack 2557.2007.06.1.0 1 AAT2557 500mA Battery Charger and 300mA LDO Regulator for Portable Systems Pin Descriptions Pin # Symbol Function 1 ENLDO 2, 8, 12, 13, 14 3 GND BYP 4 EN_BAT 5 ISET 6 7 9 10 11 BAT ADP STAT OUTLDO INLDO Enable pin for the linear regulator. When connected to logic low, the regulator is disabled and consumes less than 1µA of current. When connected to logic high, it resumes normal operation. Ground. Low noise bypass pin. Connect a 10nF capacitor between this pin and ground to improve AC ripple rejection and reduce noise. Enable pin for the battery charger. When connected to logic low, the battery charger is disabled and consumes less than 1µA of current. When connected to logic high, the charger resumes normal operation. Charge current set point. Connect a resistor from this pin to ground. Refer to typical characteristics curves for resistor selection. Battery charging and sensing. Input for USB/adapter charger. Charge status input. Open drain status output. Linear regulator output. Connect a 2.2µF capacitor from this pin to ground. Linear regulator input voltage. Connect a 1µF or greater capacitor from this pin to ground. Pin Configuration TSOPJW-14 (Top View) ENLDO GND BYP EN_BAT ISET BAT ADP 2 1 14 2 13 3 12 4 11 5 10 6 9 7 8 GND GND GND INLDO OUTLDO STAT GND 2557.2007.06.1.0 AAT2557 500mA Battery Charger and 300mA LDO Regulator for Portable Systems Absolute Maximum Ratings1 Symbol VINLDO VADP VEN VX VBYP TJ TLEAD Description Input Voltage to GND Adapter Voltage to GND ENLDO, EN_BAT Voltage to GND BAT, ISET, STAT Voltage to GND BYP Voltage to GND Operating Junction Temperature Range Maximum Soldering Temperature (at leads, 10 sec) Value Units 6.0 -0.3 to 7.5 -0.3 to 6.0 -0.3 to VADP + 0.3 -0.3 to VINLDO + 0.3 -40 to 150 300 V V V V V °C °C Value Units 625 160 mW °C/W Thermal Information Symbol PD θJA Description Maximum Power Dissipation Thermal Resistance2 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. 2557.2007.06.1.0 3 AAT2557 500mA Battery Charger and 300mA LDO Regulator for Portable Systems Electrical Characteristics1 VINLDO = VOUT(NOM) + 1V for VOUT options greater than 1.5V. IOUT = 1mA, COUT = 2.2µF, CIN = 1µF, CBYP = 10nF, TA = -40°C to +85°C, unless otherwise noted. Typical values are TA = 25°C. Symbol Description Conditions Min Typ Max Units 1.5 2.5 % 5.5 V 600 mV Linear Regulator VOUT VIN VDO ΔVOUT/ VOUT*ΔVIN ΔVOUT(Line) ΔVOUT(Load) IOUT ISC IQ ISHDN PSRR TSD THYS eN TC TEN_DLY VEN(L) VEN(H) IEN Output Voltage Tolerance IOUTLDO = 1mA TA = 25°C to 300mA TA = -40°C to +85°C Input Voltage -1.5 -2.5 VOUT + VDO2 Dropout Voltage3 IOUTLDO = 300mA 400 Line Regulation VINLDO = VOUTLDO + 1 to 5.0V 0.09 %/V 2.5 mV 60 mV mA mA µA µA IOUTLDO = 300mA, VINLDO = VOUTLDO + 1 to VOUTLDO + 2, TR/TF = 2µs Dynamic Load Regulation IOUTLDO = 1mA to 300mA, TR <5µs Output Current VOUTLDO > 1.2V Short-Circuit Current VOUTLDO < 0.4V Quiescent Current VINLDO = 5V; VENLDO = VIN Shutdown Current VINLDO = 5V; VENLDO = 0V 1kHz Power Supply Rejection IOUTLDO =10mA 10kHz Ratio 1MHz Over-Temperature Shutdown Threshold Over-Temperature Shutdown Hysteresis Output Noise Output Voltage Temperature Coefficient Enable Time Delay BYP Open Enable Threshold Low Enable Threshold High Enable Input Current VENLDO = 5.5V Dynamic Line Regulation 300 600 70 125 1.0 65 45 43 dB 145 °C 12 °C 50 µVRMS 22 ppm/°C 15 µs V V µA 0.6 1.5 1.0 1. The AAT2557 is guaranteed to meet performance specifications over the -40°C to +85°C operating temperature range and is assured by design, characterization, and correlation with statistical process controls. 2. VDO is defined as VIN - VOUT when VOUT is 98% of nominal. 3. For VOUT <2.3V, VDO = 2.5V - VOUT. 4 2557.2007.06.1.0 AAT2557 500mA Battery Charger and 300mA LDO Regulator for Portable Systems Electrical Characteristics1 VADP = 5V; TA = -40°C to +85°C, unless otherwise noted. Typical values are TA = 25°C. Symbol Description Battery Charger 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 ΔVCH/VCH Output Charge Voltage Tolerance VMIN Preconditioning Voltage Threshold VRCH Battery Recharge Voltage Threshold Current Regulation ICH Charge Current Programmable Range ΔICH/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) Enable Threshold High VEN(L) Enable Threshold Low 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 Conditions Min Rising Edge 4.0 3 Typ 150 0.5 0.3 0.4 Charge Current = 200mA VBAT = 4.25V, EN_BAT = GND VBAT = 4V, ADP Pin Open 4.158 2.85 Measured from VBAT_EOC 4.20 0.5 3.0 -0.1 15 Max Units 6.5 4 V V mV mA µA µA 1 1 2 4.242 3.15 500 mA % V 1.1 Ω 10 2 800 VADP = 5.5V 0.9 1.6 0.4 0.4 8 STAT Pin Sinks 4mA ICH = 100mA 4.4 10 10 V % V V V V V mA V % % 1. The AAT2557 is guaranteed to meet performance specifications over the -40°C to +85°C operating temperature range and is assured by design, characterization, and correlation with statistical process controls. 2557.2007.06.1.0 5 AAT2557 500mA Battery Charger and 300mA LDO Regulator for Portable Systems Typical Characteristics – Battery Charger Charging Current vs. Battery Voltage Constant Charging Current vs. Set Resistor Values (VADP = 5V) 600 1000 RSET = 3.24kΩ 100 ICH (mA) ICH (mA) 500 10 400 RSET = 5.36kΩ 300 RSET = 8.06kΩ 200 100 1 RSET = 16.2kΩ RSET = 31.6kΩ 3.1 3.7 0 1 10 100 2.7 1000 2.9 3.3 3.5 3.9 4.1 4.3 VBAT (V) RSET (kΩ Ω) End of Charge Battery Voltage vs. Supply Voltage End of Charge Voltage Regulation vs. Temperature (RSET = 8.06kΩ Ω) 4.206 4.23 RSET = 8.06kΩ 4.22 VBAT_EOC (V) VBAT_EOC (V) 4.204 4.202 4.200 RSET = 31.6kΩ 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 75 100 210 208 210 205 VBAT = 3.3V ICH (mA) ICH (mA) 50 (RSET = 8.06kΩ Ω) 220 200 190 VBAT = 3.6V VBAT = 4V 203 200 198 195 180 193 4 4.25 4.5 4.75 5 5.25 5.5 VADP (V) 6 25 Constant Charging Current vs. Temperature (RSET = 8.06kΩ Ω) 170 0 Temperature (°C) VADP (V) 5.75 6 6.25 6.5 190 -50 -25 0 25 50 75 100 Temperature (°C) 2557.2007.06.1.0 AAT2557 500mA Battery Charger and 300mA LDO Regulator for Portable Systems Typical Characteristics – Battery Charger Operating Current vs. Temperature Preconditioning Threshold Voltage vs. Temperature (RSET = 8.06kΩ Ω) (RSET = 8.06kΩ Ω) 550 3.03 3.02 450 VMIN (V) IOP (µA) 500 400 3.01 3 2.99 350 2.98 300 -50 -25 0 25 50 75 2.97 -50 100 -25 0 Temperature (°C) Preconditioning Charge Current vs. Temperature (RSET = 8.06kΩ Ω) ITRICKLE (mA) ITRICKLE (mA) 20.4 20.2 20.0 19.8 19.6 25 50 75 RSET = 5.36kΩ 30 RSET = 8.06kΩ 20 0 100 4 4.2 4.4 4.6 4.8 5 5.2 5.4 5.6 5.8 6 6.2 6.4 VADP (V) Recharging Threshold Voltage vs. Temperature Sleep Mode Current vs. Supply Voltage (RSET = 8.06kΩ Ω) 800 4.18 700 4.16 85°C 600 ISLEEP (nA) 4.14 4.12 4.10 4.08 500 400 300 4.06 200 4.04 100 4.02 RSET = 31.6kΩ RSET = 16.2kΩ Temperature (°C) (RSET = 8.06kΩ Ω) VRCH (V) 40 10 19.4 0 100 RSET = 3.24kΩ 50 -25 75 60 20.6 -50 50 Preconditioning Charge Current vs. Supply Voltage 20.8 19.2 25 Temperature (°C) -50 -25 0 25 50 Temperature (°C) 2557.2007.06.1.0 75 100 25°C -40°C 0 4 4.25 4.5 4.75 5 5.25 5.5 5.75 6 6.25 6.5 VADP (V) 7 AAT2557 500mA Battery Charger and 300mA LDO Regulator for Portable Systems Typical Characteristics – Battery Charger VEN(H) vs. Supply Voltage VEN(L) vs. Supply Voltage (RSET = 8.06kΩ Ω) (RSET = 8.06kΩ Ω) 1.2 1.1 1 0.9 25°C 0.8 85°C 0.9 0.8 25°C 0.7 85°C 0.6 0.7 4 4.25 4.5 4.75 5 5.25 5.5 VADP (V) 8 -40°C 1 -40°C VEN(L) (V) VEN(H) (V) 1.1 5.75 6 6.25 6.5 4 4.25 4.5 4.75 5 5.25 5.5 5.75 6 6.25 6.5 VADP (V) 2557.2007.06.1.0 AAT2557 500mA Battery Charger and 300mA LDO Regulator for Portable Systems Typical Characteristics – LDO Regulator Dropout Voltage vs. Temperature Dropout Characteristics 3.2 IL = 300mA 480 360 300 IL = 100mA IL = 150mA 240 180 120 60 IL = 50mA 0 -40 -30 -20 -10 0 IOUT = 0mA 3.0 420 Output Voltage (V) Dropout Voltage (mV) 540 2.8 IOUT = 300mA IOUT = 150mA 2.6 2.4 IOUT = 10mA 2.2 2.0 2.7 10 20 30 40 50 60 70 80 90 100 110 120 2.8 2.9 Temperature (°C) 3.1 3.2 3.3 Ground Current vs. Input Voltage 90 500 Ground Current (μA) 450 Dropout Voltage (mV) 3.0 Input Voltage (V) Dropout Voltage vs. Output Current 400 350 300 85°C 250 200 25°C 150 -40°C 100 80 70 60 IOUT=300mA 50 IOUT=150mA IOUT=50mA 40 IOUT=0mA 30 IOUT=10mA 20 10 50 0 0 50 100 150 200 250 0 300 2 2.5 3 3.5 4 4.5 5 Input Voltage (V) Output Current (mA) Quiescent Current vs. Temperature Output Voltage vs. Temperature 1.203 100 90 1.202 80 Output Voltage (V) Quiescent Current (μA) IOUT = 100mA IOUT = 50mA 70 60 50 40 30 20 10 0 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120 Temperature (°C) 2557.2007.06.1.0 1.201 1.200 1.199 1.198 1.197 1.196 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 Temperature (°C) 9 AAT2557 500mA Battery Charger and 300mA LDO Regulator for Portable Systems Typical Characteristics – LDO Regulator LDO Turn-On Time from Enable LDO Initial Power-Up Response Time (VIN Present) 3 2 3 1 2 0 1 0 3 Enable Voltage (top) (V) Input Voltage (top) (V) 4 4 Output Voltage (bottom) (V) 5 Output Voltage (bottom) (V) 6 2 4 1 3 0 2 1 0 Time (50µs/div) Time (5µs/div) Turn-Off Response Time Line Transient Response 3 2 1 0 Input Voltage (top) (V) 0 6 5 VIN 4 3.00 VOUT 2.99 2.98 Time (5µs/div) Time (100µs/div) Load Transient Response 2.75 100 0 IOUT Output Voltage (top) (V) Output Voltage (top) (V) 2.80 3.0 2.9 2.8 2.7 VOUT 400 300 200 IOUT 100 0 Output Current (bottom) (mA) VOUT Time (100µs/div) 10 (VOUT = 2.8V) Output Current (bottom) (mA) 2.85 Load Transient Response 300mA (VOUT = 2.8V) 2.90 Output Voltage (bottom) (V) 5 Output Voltage (bottom) (V) Enable Voltage (top) (V) (IOUT = 100mA) Time (10µs/div) 2557.2007.06.1.0 AAT2557 500mA Battery Charger and 300mA LDO Regulator for Portable Systems Typical Characteristics – LDO Regulator Enable Threshold Voltage (V) VEN(L) and VEN(H) vs. VIN 1.250 1.225 1.200 VEN(H) 1.175 1.150 1.125 VEN(L) 1.100 1.075 1.050 2.5 3.0 3.5 4.0 4.5 5.0 5.5 Input Voltage (V) 2557.2007.06.1.0 11 AAT2557 500mA Battery Charger and 300mA LDO Regulator for Portable Systems Functional Block Diagram Reverse Blocking BAT ADP OverTemperature Protection Charge Control - STAT Constant Current + + ISET - VREF UVLO EN_BAT INLDO Err. Amp. BYP VREF OverCurrent Protection OUTLDO ENLDO Functional Description The AAT2557 is a high performance power management IC comprised of a lithium-ion/polymer battery charger and a linear regulator. The linear regulator is designed for high-speed turn-on, fast transient response, good power supply ripple rejection, and low noise. Battery Charger The battery charger is designed for single-cell lithium-ion/polymer batteries using a constant current and constant voltage algorithm. The battery 12 GND charger operates from the adapter/USB input voltage range from 4V to 6.5V. The adapter/USB charging current level can be programmed up to 500mA for rapid charging applications. A status monitor output pin is provided to indicate the battery charge state by directly driving one external LED. Internal device temperature and charging 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. Other features include an integrated reverse blocking diode and sense resistor. 2557.2007.06.1.0 AAT2557 500mA Battery Charger and 300mA LDO Regulator for Portable Systems Linear Regulator Protection Circuitry The advanced circuit design of the linear regulator has been specifically optimized for very fast startup. This proprietary CMOS LDO has also been tailored for superior transient response characteristics. These traits are particularly important for applications that require fast power supply timing. Over-Voltage Protection A battery charger over-voltage protection event is defined as a condition where the voltage on the BAT pin exceeds the over-voltage protection threshold (VOVP) (4.4V). If this over-voltage condition occurs, the charger control circuitry will shut down the device. The charger will resume normal charging operation after the over-voltage condition is removed. The high-speed turn-on capability is enabled through implementation of a fast-start control circuit which accelerates the power-up behavior of fundamental control and feedback circuits within the LDO regulator. The LDO regulator output has been specifically optimized to function with lowcost, low-ESR ceramic capacitors; however, the design will allow for operation over a wide range of capacitor types. The regulator comes with complete short-circuit and thermal protection. The combination of these two internal protection circuits gives a comprehensive safety system to guard against extreme adverse operating conditions. The regulator features an enable/disable function. This pin (ENLDO) is active high and is compatible with CMOS logic. To assure the LDO regulator will switch on, the ENLDO turn-on control level must be greater than 1.5V. The LDO regulator will go into the disable shutdown mode when the voltage on the ENLDO pin falls below 0.6V. If the enable function is not needed in a specific application, it may be tied to INLDO to keep the LDO regulator in a continuously on state. Under-Voltage Lockout The AAT2557 has internal circuits for UVLO and power on reset features. If the ADP supply voltage drops below the UVLO threshold, the battery 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 automatically resume charging in the appropriate mode for the condition of the battery. 2557.2007.06.1.0 Over-Temperature Protection The battery charger has a thermal protection circuit which will shut down charging functions when the internal die temperature exceeds the preset thermal limit threshold (145°C). Once the internal die temperature falls below the thermal limit, normal charging operation will resume. Short-Circuit Protection The AAT2557’s LDO contains an internal short-circuit protection circuit that will trigger when the output load current exceeds the internal threshold limit. Under short-circuit conditions, the output of the LDO regulator will be current limited until the short-circuit condition is removed from the output or until the package power dissipation exceeds the device thermal limit. Thermal Protection The AAT2557’s LDO has an internal thermal protection circuit which will turn on when the device die temperature exceeds 145°C. The internal thermal protection circuit will actively turn off the LDO regulator output pass device to prevent the possibility of overtemperature damage. The LDO regulator output will remain in a shutdown state until the internal die temperature falls back below the 145°C trip point. The combination and interaction between the shortcircuit and thermal protection systems allow the LDO regulator to withstand indefinite short-circuit conditions without sustaining permanent damage. 13 AAT2557 500mA Battery Charger and 300mA LDO Regulator for Portable Systems 15mA up to a maximum of 500mA. Constant current charging will continue until the battery voltage reaches the voltage regulation point, VBAT. When the battery voltage reaches VBAT, the battery charger begins constant voltage mode. The regulation voltage is factory programmed to a nominal 4.2V (±0.5%) and will continue charging until the charging current has reduced to 10% of the programmed current. Battery Charging Operation Battery charging commences only after checking several conditions in order to maintain a safe charging environment. The input supply (ADP) must be above the minimum operating voltage (UVLO) and the enable pin must be high (internally pulled down). When the battery is connected to the BAT pin, the charger checks the condition of the battery and determines which charging mode to apply. If the battery voltage is below VMIN, the charger begins battery pre-conditioning by charging at 10% of the programmed constant current; e.g., if the programmed current is 150mA, then the pre-conditioning current (trickle charge) is 15mA. Pre-conditioning is purely a safety precaution for a deeply discharged cell and will also reduce the power dissipation in the internal series pass MOSFET when the input-output voltage differential is at its highest. After the charge cycle is complete, the pass device turns off and the device automatically goes into a power-saving sleep mode. During this time, the series pass device will block current in both directions, preventing the battery from discharging through the IC. The battery charger will remain in sleep mode, even if the charger source is disconnected, until one of the following events occurs: the battery terminal voltage drops below the VRCH threshold; the charger EN pin is recycled; or the charging source is reconnected. In all cases, the charger will monitor all parameters and resume charging in the most appropriate mode. Pre-conditioning continues until the battery voltage reaches VMIN (see Figure 1). At this point, the charger begins constant-current charging. The current level for this mode is programmed using a single resistor from the ISET pin to ground. Programmed current can be set from a minimum Preconditioning Trickle Charge Phase Constant Current Charge Phase Constant Voltage Charge Phase Charge Complete Voltage 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. 14 2557.2007.06.1.0 AAT2557 500mA Battery Charger and 300mA LDO Regulator for Portable Systems Battery Charging System Operation Flow Chart Enable No Power On Reset Yes Power Input Voltage VADP > 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 BAT_EOC > VBAT No Voltage Phase Test IBAT > ITERM No Charge Completed 2557.2007.06.1.0 15 AAT2557 500mA Battery Charger and 300mA LDO Regulator for Portable Systems Application Information Soft Start / Enable Normal ICHARGE (mA) Set Resistor Value R1 (kΩ) 500 400 300 250 200 150 100 50 40 30 20 15 3.24 4.12 5.36 6.49 8.06 10.7 16.2 31.6 38.3 53.6 78.7 105 The EN_BAT pin is internally pulled down. When pulled to a logic high level, the battery charger is enabled. When left open or pulled to a logic low level, the battery charger is shut down and forced into the sleep state. Charging will be halted regardless of the battery voltage or charging state. When it 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 from the BAT pin. The LDO is enabled when the ENLDO pin is pulled high. The control and feedback circuits have been optimized for high-speed, monotonic turn-on characteristics. Table 1: RSET Values. 1000 Constant current charge levels up to 500mA may be programmed by the user when powered from a sufficient input power source. The battery charger 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. 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 500mA may be set by selecting the appropriate resistor value from Table 1. 16 ICH (mA) Adapter or USB Power Input 100 10 1 1 10 100 1000 RSET (kΩ Ω) Figure 2: Constant Charging Current vs. Set Resistor Values. Charge Status Output The AAT2557 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 several conditions, as shown in Table 2. 2557.2007.06.1.0 AAT2557 500mA Battery Charger and 300mA LDO Regulator for Portable Systems Event Description Status No battery charging activity Battery charging via adapter or USB port Charging completed OFF ON OFF Table 2: LED Status Indicator. proximity to other heat generating devices in a given application design. The ambient temperature around the 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: 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 LEDs. It is not recommended to exceed 8mA for driving an individual status LED. Where: The required ballast resistor values can be estimated using the following formulas: TA R 1= (VADP - VF(LED)) ILED PD(MAX) = (TJ(MAX) - TA) θJA PD(MAX) = Maximum Power Dissipation (W) θJA = Package Thermal Resistance (°C/W) TJ(MAX) = Maximum Device Junction Temperature (°C) [135°C] = Ambient Temperature (°C) PD = [(VADP - VBAT) · ICH + (VADP · IOP)] + (VINLDO - VOUTLDO) ILDOLOAD + VINLDO · IQLDO Where: Example: R1 = (5.5V - 2.0V) = 1.75kΩ 2mA Note: Red LED forward voltage (VF) is typically 2.0V @ 2mA. PD = Total Power Dissipation by the Device VADP = ADP/USB 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] VINLDO = Input Voltage as Seen at the INLDO Pin Thermal Considerations The AAT2557 is offered in a TSOPJW-14 package which can provide up to 625mW of power dissipation when it is properly bonded to a printed circuit board and has a maximum thermal resistance of 160°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 2557.2007.06.1.0 VOUTLDO = Output Voltage as Seen at the OUTLDO Pin ILDOLOAD = LDO Load Current IQLDO = LDO Quiescent Current 17 AAT2557 500mA Battery Charger and 300mA LDO Regulator for Portable Systems 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 θJA ICH(MAX) = VIN - VBAT In general, the worst condition is the greatest voltage drop across the IC, when battery voltage is charged up to the preconditioning voltage threshold. Capacitor Selection Linear Regulator Input Capacitor An input capacitor greater than 1µF will offer superior input line transient response and maximize power supply ripple rejection. Ceramic, tantalum, or aluminum electrolytic capacitors may be selected for CIN. There is no specific capacitor ESR requirement for CIN. However, for 300mA LDO regulator output operation, ceramic capacitors are recommended for CIN due to their inherent capability over tantalum capacitors to withstand input current surges from low impedance sources such as batteries in portable devices. Battery Charger 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 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 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 10µF 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. 18 Linear Regulator Output Capacitor For proper load voltage regulation and operational stability, a capacitor is required between OUT and GND. The COUT capacitor connection to the LDO regulator ground pin should be made as directly as practically possible for maximum device performance. Since the regulator has been designed to function with very low ESR capacitors, ceramic capacitors in the 1.0µF to 10µF range are recommended for best performance. Applications utilizing the exceptionally low output noise and optimum power supply ripple rejection should use 2.2µF or greater for COUT. In low output current applications, where output load is less than 10mA, the minimum value for COUT can be as low as 0.47µF. Battery Charger Output Capacitor The AAT2557 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 AAT2557 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 10µF may be required to prevent the device from cycling on and off when no battery is present. Bypass Capacitor and Low Noise Applications A bypass capacitor pin is provided to enhance the low noise characteristics of the AAT2557 LDO regulator. The bypass capacitor is not necessary for operation of the AAT2557. However, for best device performance, a small ceramic capacitor should be placed between the bypass pin (BYP) and the device ground pin (GND). The value of CBYP may range from 470pF to 10nF. For lowest noise and best possible power supply ripple rejection performance, a 10nF capacitor should be used. To practically realize the highest power supply ripple rejection and lowest output noise performance, it is critical that the capacitor connection between the BYP pin and GND pin be direct and PCB traces should be as short as possible. Refer to the PCB Layout Recommendations section of this document for examples. There is a relationship between the bypass capacitor value and the LDO regulator turn-on and turnoff time. In applications where fast device turn-on and 2557.2007.06.1.0 AAT2557 500mA Battery Charger and 300mA LDO Regulator for Portable Systems turn-off time are desired, the value of CBYP should be reduced. Printed Circuit Board Layout Considerations In applications where low noise performance and/or ripple rejection are less of a concern, the bypass capacitor may be omitted. The fastest device turn-on time will be realized when no bypass capacitor is used. For the best results, it is recommended to physically place the battery pack as close as possible to the AAT2557 BAT pin. To minimize voltage drops on the PCB, keep the high current carrying traces adequately wide. The input capacitors should connect as closely as possible to ADP and INLDO. 2557.2007.06.1.0 19 AAT2557 500mA Battery Charger and 300mA LDO Regulator for Portable Systems Manufacturer Murata Murata Murata Murata Murata Murata Murata Murata Part Number Value (µF) Voltage Rating Temp. Co. Case Size GRM21BR61A106KE19 GRM188R60J475KE19 GRM188R61A225KE34 GRM188R60J225KE19 GRM188R61A105KA61 GRM185R60J105KE26 GRM188F51H103ZA01 GRM155F51H103ZA01 10 4.7 2.2 2.2 1.0 1.0 0.01 0.01 10 6.3 10 6.3 10 6.3 50 50 X5R X5R X5R X5R X5R X5R Y5V Y5V 0805 0603 0603 0603 0603 0603 0603 0402 Table 3: Surface Mount Capacitors. 20 2557.2007.06.1.0 AAT2557 500mA Battery Charger and 300mA LDO Regulator for Portable Systems Ordering Information Package Marking1 Part Number (Tape and Reel)2 TSOPJW-14 VKXYY AAT2557ITO-CT-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. Legend Voltage Code 1.2 1.5 1.8 1.9 2.5 2.6 2.7 2.8 2.85 2.9 3.0 3.3 4.2 E G I Y N O P Q R S T W C 1. XYY = assembly and date code. 2. Sample stock is generally held on part numbers listed in BOLD. 2557.2007.06.1.0 21 AAT2557 500mA Battery Charger and 300mA LDO Regulator for Portable Systems Package Information TSOPJW-14 2.85 ± 0.20 2.40 ± 0.10 0.20 BSC 0.40 BSC Top View 7° NOM 0.04 REF + 0.05 0.05 - 0.04 0.15 ± 0.05 + 0.05 1.05 - 0.00 + 0.000 1.00 - 0.075 + 0.05 3.05 - 0.10 4° ± 4° 0.45 ± 0.15 2.75 ± 0.25 All dimensions in millimeters. © Advanced Analogic Technologies, Inc. AnalogicTech cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in an AnalogicTech product. No circuit patent licenses, copyrights, mask work rights, or other intellectual property rights are implied. AnalogicTech reserves the right to make changes to their products or specifications or to discontinue any product or service without notice. Except as provided in AnalogicTech’s terms and conditions of sale, AnalogicTech assumes no liability whatsoever, and AnalogicTech disclaims any express or implied warranty relating to the sale and/or use of AnalogicTech products including liability or warranties relating to fitness for a particular purpose, merchantability, or infringement of any patent, copyright or other intellectual property right. In order to minimize risks associated with the customer’s applications, adequate design and operating safeguards must be provided by the customer to minimize inherent or procedural hazards. Testing and other quality control techniques are utilized to the extent AnalogicTech deems necessary to support this warranty. Specific testing of all parameters of each device is not necessarily performed. AnalogicTech and the AnalogicTech logo are trademarks of Advanced Analogic Technologies Incorporated. All other brand and product names appearing in this document are registered trademarks or trademarks of their respective holders. Advanced Analogic Technologies, Inc. 830 E. Arques Avenue, Sunnyvale, CA 94085 Phone (408) 737-4600 Fax (408) 737-4611 22 2557.2007.06.1.0