PRODUCT DATASHEET AAT2556 SystemPowerTM Battery Charger and Step-Down Converter for Portable Applications General Description Features The AAT2556 is a member of AnalogicTech's Total Power Management ICTM (TPMICTM) product family. It is a fully integrated 500mA battery charger plus a 250mA stepdown converter. The input voltage range is 4V to 6.5V for the battery charger and 2.7V to 5.5V for the step-down converter, making it ideal for single-cell lithium-ion/polymer battery-powered applications. * Battery Charger: Input Voltage Range: 4V to 6.5V Programmable Charging Current up to 500mA Highly Integrated Battery Charger Charging Device Reverse Blocking Diode * Step-Down Converter: Input Voltage Range: 2.7V to 5.5V Output Voltage Range: 0.6V to VIN 250mA Output Current Up to 96% Efficiency 30A Quiescent Current 1.5MHz Switching Frequency 100s Start-Up Time * Short-Circuit, Over-Temperature, and Current Limit Protection * TDFN33-12 Package * -40C to +85C Temperature Range The battery charger is a complete constant current/ constant voltage linear charger. It offers an integrated pass device, reverse blocking protection, high current accuracy and voltage regulation, charge status, and charge termination. The charging current is programmable via external resistor from 15mA to 500mA. In addition to standard features, the device offers over-voltage, current limit, and thermal protection. The step-down converter is a highly integrated converter operating at 1.5MHz of switching frequency, minimizing the size of external components while keeping switching losses low. It has independent input and enable pins. The output voltage ranges from 0.6V to the input voltage. The feedback and control deliver excellent load regulation and transient response with a small output inductor and capacitor. Applications * * * * * * The AAT2556 is available in a Pb-free, thermallyenhanced TDFN33-12 package and is rated over the -40C to +85C temperature range. BluetoothTM Headsets Cellular Phones Handheld Instruments MP3 and Portable Music Players PDAs and Handheld Computers Portable Media Players Typical Application Adapter / USB Input VIN ADP EN_BUCK STAT BATT + VOUT BAT EN_BAT L= 3.3H C LX FB RFB2 2556.2009.08.1.3 BATT - ISET RSET GND www.analogictech.com Battery Pack RFB1 COUT System Enable 1 PRODUCT DATASHEET AAT2556 SystemPowerTM Battery Charger and Step-Down Converter for Portable Applications Pin Descriptions Pin # Symbol 1 2, 8, 10 FB GND 3 EN_BUCK 4 EN_BAT 5 ISET 6 7 9 BAT STAT ADP 11 LX 12 EP VIN Function Feedback input. This pin must be connected directly to an external resistor divider. Nominal voltage is 0.6V. Ground. Enable pin for the step-down converter. When connected to logic low, the step-down converter is disabled and it consumes less than 1A of current. When connected to logic high, it resumes normal operation. Enable pin for the battery charger. When internally pulled down, the battery charger is disabled and it consumes less than 1A of current. When connected to logic high, it resumes normal operation. Charge current set point. Connect a resistor from this pin to ground. Refer to typical curves for resistor selection. Battery charging and sensing. Charge status input. Open drain status input. Input for USB/adapter charger. Output of the step-down converter. Connect the inductor to this pin. Internally, it is connected to the drain of both high- and low-side MOSFETs. Input voltage for the step-down converter. Exposed paddle (bottom): connect to ground directly beneath the package. Pin Configuration TDFN33-12 (Top View) FB GND EN_BUCK EN_BAT ISET BAT 2 1 12 2 11 3 10 4 9 5 8 6 7 VIN LX GND ADP GND STAT www.analogictech.com 2556.2009.08.1.3 PRODUCT DATASHEET AAT2556 SystemPowerTM Battery Charger and Step-Down Converter for Portable Applications Absolute Maximum Ratings1 Symbol VIN VADP VLX VFB VEN VX TJ TLEAD Description Input Voltage to GND Adapter Voltage to GND LX to GND FB to GND EN_BAT and EN_BUCK to GND BAT, ISET and STAT 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 VIN + 0.3 -0.3 to VIN + 0.3 -0.3 to 6.0 -0.3 to VADP + 0.3 -40 to 150 300 V V V V V V C C Value Units 2.0 50 W C/W Thermal Information Symbol PD JA 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. 2556.2009.08.1.3 www.analogictech.com 3 PRODUCT DATASHEET AAT2556 SystemPowerTM Battery Charger and Step-Down Converter for Portable Applications Electrical Characteristics1 VIN = 3.6V; TA = -40C to +85C, unless otherwise noted. Typical values are TA = 25C. Symbol Description Conditions Step-Down Converter VIN Input Voltage VUVLO VOUT VOUT IQ ISHDN ILIM RDS(ON)H RDS(ON)L ILXLEAK VLinereg/ VIN VFB IFB FOSC TS TSD THYS VEN(L) VEN(H) IEN Min Typ 2.7 VIN Rising Hysteresis VIN Falling IOUT = 0 to 250mA, VIN = 2.7V to 5.5V UVLO Threshold Output Voltage Tolerance2 Output Voltage Range Quiescent Current Shutdown Current P-Channel Current Limit High-Side Switch On Resistance Low-Side Switch On Resistance LX Leakage Current Max Units 5.5 2.7 V V mV V % V A A mA A 200 1.8 -3.0 0.6 No Load EN = GND 3.0 VIN 30 1.0 600 0.59 0.42 VIN = 5.5V, VLX = 0 to VIN Line Regulation VIN = 2.7V to 5.5V Feedback Threshold Voltage Accuracy FB Leakage Current Oscillator Frequency Startup Time Over-Temperature Shutdown Threshold Over-Temperature Shutdown Hysteresis Enable Threshold Low Enable Threshold High Input Low Current VIN = 3.6V VOUT = 1.0V 1.0 0.2 0.591 0.600 %/V 0.609 0.2 1.5 100 140 15 From Enable to Output Regulation 0.6 VIN = VEN = 5.5V 1.4 -1.0 1.0 V A MHz s C C V V A 1. The AAT2556 is guaranteed to meet performance specifications over the -40C to +85C operating temperature range and is assured by design, characterization, and correlation with statistical process controls. 2. Output voltage tolerance is independent of feedback resistor network accuracy. 4 www.analogictech.com 2556.2009.08.1.3 PRODUCT DATASHEET AAT2556 SystemPowerTM Battery Charger and Step-Down Converter for Portable Applications Electrical Characteristics1 VADP = 5V; TA = -40C to +85C, unless otherwise noted. Typical values are TA = 25C. Symbol Description Conditions Battery Charger Operation VADP Adapter Voltage Range VUVLO Under-Voltage Lockout (UVLO) UVLO Hysteresis IOP Operating Current Shutdown Current ISHUTDOWN ILEAKAGE Reverse Leakage Current from BAT Pin Voltage Regulation VBAT_EOC End of Charge Accuracy VCH/VCH Output Charge Voltage Tolerance VMIN Preconditioning Voltage Threshold VRCH Battery Recharge Voltage Threshold Current Regulation ICH Charge Current Programmable Range ICH/ICH Charge Current Regulation Tolerance ISET Pin Voltage VSET KI_A Current Set Factor: ICH/ISET Charging Devices RDS(ON) Charging Transistor On Resistance Logic Control/Protection Input High Threshold VEN(H) VEN(L) Input Low Threshold VSTAT Output Low Voltage ISTAT STAT Pin Current Sink Capability VOVP Over-Voltage Protection Threshold ITK/ICHG Pre-Charge Current ITERM/ICHG Charge Termination Threshold Current Rising Edge Min Typ 4.0 3 150 0.5 0.3 0.4 Charge Current = 200mA VBAT = 4.25V, EN = GND VBAT = 4V, ADP Pin Open 4.158 2.85 Measured from VBAT_EOC 4.20 0.5 3.0 -0.1 15 Max Units 6.5 4 V V mV mA A A 1 1 2 4.242 3.15 500 mA % V 1.1 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 AAT2556 output charge voltage is specified over the 0 to 70C ambient temperature range; operation over the -25C to +85C temperature range is guaranteed by design. 2556.2009.08.1.3 www.analogictech.com 5 PRODUCT DATASHEET AAT2556 SystemPowerTM Battery Charger and Step-Down Converter for Portable Applications Typical Characteristics - Step-Down Converter Efficiency vs. Load DC Load Regulation (VOUT = 1.8V; L = 3.3H) 100 VIN = 2.7V VIN = 5.0V VIN = 3.6V Output Error (%) Efficiency (%) 90 (VOUT = 1.8V; L = 3.3H) 1.0 80 VIN = 5.5V 70 60 VIN = 4.2V 50 40 0.1 1 10 100 0.5 VIN = 3.6V 0.0 VIN = 2.7V -0.5 1 10 Output Current (mA) (VOUT = 1.2V; L = 1.5H) 1.0 100 Efficiency (%) Output Error (%) VIN = 2.7V 90 VIN = 3.6V 70 60 VIN = 5.5V VIN = 5.0V 50 VIN = 4.2V 40 0.1 1 VIN = 5.0V 0.5 VIN = 5.5V 0.0 VIN = 3.6V VIN = 4.2V -0.5 VIN = 2.7V 10 100 -1.0 0.1 1000 1 Soft Start Line Regulation (VOUT = 1.8V) 1.2 2.0 1.0 1.0 0.8 0.6 0.0 VO 0.4 0.2 -2.0 -3.0 -4.0 0.5 1.4 3.0 -1.0 0.0 IL -0.2 -5.0 1000 0.6 1.6 VEN 4.0 100 (VIN = 3.6V; VOUT = 1.8V; IOUT = 250mA; CFF = 100pF) -0.4 Accuracy (%) 5.0 10 Output Current (mA) Inductor Current (bottom) (A) Enable and Output Voltage (top) (V) Output Current (mA) IOUT = 0mA 0.4 0.3 IOUT = 50mA 0.2 IOUT = 150mA 0.1 0.0 -0.1 IOUT = 10mA IOUT = 250mA -0.2 -0.3 Time (100s/div) 6 1000 DC Load Regulation (VOUT = 1.2V; L = 1.5H) 30 100 Output Current (mA) Efficiency vs. Load 80 VIN = 5.0V VIN = 4.2V -1.0 0.1 1000 VIN = 5.5V 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 Input Voltage (V) www.analogictech.com 2556.2009.08.1.3 PRODUCT DATASHEET AAT2556 SystemPowerTM Battery Charger and Step-Down Converter for Portable Applications Typical Characteristics - Step-Down Converter Output Voltage Error vs. Temperature Switching Frequency Variation vs. Temperature (VIN = 3.6V; VOUT = 1.8V; IOUT = 250mA) (VIN = 3.6V; VOUT = 1.8V) 3.0 2.0 8.0 Variation (%) Output Error (%) 10.0 1.0 0.0 -1.0 6.0 4.0 2.0 0.0 -2.0 -4.0 -6.0 -2.0 -8.0 -3.0 -40 -20 0 20 40 60 80 -10.0 100 -40 -20 0 Temperature (C) 20 40 60 80 100 Temperature (C) Frequency Variation vs. Input Voltage No Load Quiescent Current vs. Input Voltage (VOUT = 1.8V) 50 1.0 Supply Current (A) Frequency Variation (%) 2.0 0.0 -1.0 -2.0 -3.0 -4.0 2.7 3.1 3.5 3.9 4.3 4.7 5.1 85C 30 25C 25 -40C 20 15 3.1 3.9 4.3 4.7 5.1 P-Channel RDS(ON) vs. Input Voltage N-Channel RDS(ON) vs. Input Voltage 5.5 750 120C 100C 800 700 120C 650 85C 700 600 25C 85C 550 500 450 25C 350 3.0 3.5 4.0 4.5 5.0 5.5 6.0 300 Input Voltage (V) 2556.2009.08.1.3 100C 600 400 400 2.5 3.5 Input Voltage (V) RDS(ON)L (m ) RDS(ON)H (m ) 35 Input Voltage (V) 900 300 40 10 2.7 5.5 1000 500 45 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 Input Voltage (V) www.analogictech.com 7 PRODUCT DATASHEET AAT2556 SystemPowerTM Battery Charger and Step-Down Converter for Portable Applications Typical Characteristics - Step-Down Converter Load Transient Response Load Transient Response (10mA to 250mA; VIN = 3.6V; VOUT = 1.8V; COUT = 4.7F; CFF = 100pF) (10mA to 250mA; VIN = 3.6V; VOUT = 1.8V; COUT = 4.7F) 1.7 IO 1.6 ILX 1.5 1.4 1.3 1.2 1.9 Output Voltage (top) (V) Output Voltage (top) (V) VO 1.8 2.0 1.8 1.4 1.6 0.8 1.4 0.4 ILX 0.2 1.3 0.0 1.2 -0.2 Line Response Output Ripple (VOUT = 1.8V @ 250mA; CFF = 100pF) (VIN = 3.6V; VOUT = 1.8V; IOUT = 1mA) 6.5 6.0 1.75 5.5 1.70 5.0 1.65 4.5 VIN 4.0 1.55 3.5 1.50 3.0 Time (25s/div) 20 0 0.07 0.06 VO 0.05 -20 0.04 -40 0.03 -60 0.02 -80 -100 0.01 IL Inductor Current (bottom) (A) VO 40 Output Voltage (AC Coupled) (top) (mV) 7.0 1.85 Input Voltage (bottom) (V) Output Voltage (top) (V) 0.6 IO 1.5 Time (25s/div) 1.90 1.60 1.0 1.7 Time (25s/div) 1.80 1.2 VO Load and Inductor Current (bottom) (200mA/div) 1.9 Load and Inductor Current (bottom) (200mA/div) 2.0 0.00 -120 -0.01 Time (2s/div) Output Ripple (VIN = 3.6V; VOUT = 1.8V; IOUT = 250mA) 20 0 0.8 0.7 VO 0.6 -20 0.5 -40 0.4 -60 0.3 -80 -100 0.2 IL Inductor Current (bottom) (A) Output Voltage (AC Coupled) (top) (V) 40 0.1 -120 0.0 Time (200ns/div) 8 www.analogictech.com 2556.2009.08.1.3 PRODUCT DATASHEET AAT2556 SystemPowerTM Battery Charger and Step-Down Converter for Portable Applications Typical Characteristics - Battery Charger Charging Current vs. Battery Voltage Constant Charging Current vs. Set Resistor Values (VADP = 5V) 600 1000 RSET = 3.24k 100 ICH (mA) ICH (mA) 500 10 400 RSET = 5.36k 300 RSET = 8.06k 200 100 1 RSET = 16.2k RSET = 31.6k 3.1 3.7 0 1 10 100 2.7 1000 2.9 3.3 3.5 3.9 4.1 RSET (k ) VBAT (V) End of Charge Battery Voltage vs. Supply Voltage End of Charge Voltage Regulation vs. Temperature 4.3 (RSET = 8.06k ) 4.206 4.23 RSET = 8.06k 4.22 VBAT_EOC (V) VBAT_EOC (V) 4.204 4.202 4.200 RSET = 31.6k 4.198 4.196 4.194 4.21 4.20 4.19 4.18 4.5 4.75 5 5.25 5.5 5.75 6 6.25 4.17 6.5 -50 -25 Constant Charging Current vs. Supply Voltage 50 75 100 (RSET = 8.06k ) 210 220 208 210 205 VBAT = 3.3V ICH (mA) ICH (mA) 25 Constant Charging Current vs. Temperature (RSET = 8.06k ) 200 190 VBAT = 3.6V VBAT = 4V 203 200 198 195 180 170 0 Temperature (C) VADP (V) 193 4 4.25 4.5 4.75 5 5.25 5.5 5.75 6 6.25 6.5 190 VADP (V) 2556.2009.08.1.3 -50 -25 0 25 50 75 100 Temperature (C) www.analogictech.com 9 PRODUCT DATASHEET AAT2556 SystemPowerTM Battery Charger and Step-Down Converter for Portable Applications Typical Characteristics - Battery Charger Operating Current vs. Temperature Preconditioning Threshold Voltage vs. Temperature (RSET = 8.06k ) (RSET = 8.06k ) 550 3.03 3.02 450 VMIN (V) IOP (A) 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 = 8.06k ) ITRICKLE (mA) ITRICKLE (mA) 20.4 20.2 20.0 19.8 19.6 25 50 75 RSET = 8.06k 20 4 4.2 4.4 4.6 5 5.2 5.4 5.6 5.8 6 6.2 6.4 Recharging Threshold Voltage vs. Temperature Sleep Mode Current vs. Supply Voltage (RSET = 8.06k ) 800 700 85C 600 ISLEEP (nA) 4.14 4.12 4.10 4.08 500 400 300 4.06 200 4.04 100 -50 4.8 VADP (V) 4.16 4.02 RSET = 31.6k RSET = 16.2k Temperature (C) 4.18 -25 0 25 50 75 100 Temperature (C) 10 RSET = 5.36k 30 0 100 (RSET = 8.06k ) VRCH (V) 40 10 19.4 0 100 RSET = 3.24k 50 -25 75 60 20.6 -50 50 Preconditioning Charge Current vs. Supply Voltage 20.8 19.2 25 Temperature (C) -40C 25C 0 4 4.25 4.5 4.75 5 5.25 5.5 5.75 6 6.25 6.5 VADP (V) www.analogictech.com 2556.2009.08.1.3 PRODUCT DATASHEET AAT2556 SystemPowerTM Battery Charger and Step-Down Converter for Portable Applications Typical Characteristics - Battery Charger VEN(H) vs. Supply Voltage VEN(L) vs. Supply Voltage (RSET = 8.06k ) (RSET = 8.06k ) 1.2 1.1 -40C 1 -40C VEN(L) (V) VEN(H) (V) 1.1 1 0.9 25C 0.8 85C 0.9 0.8 25C 0.7 85C 0.6 0.7 4 4.25 4.5 4.75 5 5.25 5.5 5.75 6 6.25 6.5 VADP (V) 2556.2009.08.1.3 4 4.25 4.5 4.75 5 5.25 5.5 5.75 6 6.25 6.5 VADP (V) www.analogictech.com 11 PRODUCT DATASHEET AAT2556 SystemPowerTM Battery Charger and Step-Down Converter for Portable Applications Functional Block Diagram Reverse Blocking BAT ADP + Constant Current STAT OverTemperature Protection Charge Control + - ISET VREF EN_BAT UVLO VIN FB DH + LX Logic VREF DL EN_BUCK Input GND Functional Description The AAT2556 is a high performance power system comprised of a 500mA lithium-ion/polymer battery charger and a 250mA step-down converter. The battery charger is designed for single-cell lithium-ion/ polymer batteries using a constant current and constant voltage algorithm. The battery 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. The step-down converter operates with an input voltage of 2.7V to 5.5V. The switching frequency is 1.5MHz, minimizing the size of the inductor. Under light load conditions, the device enters power-saving mode; the switching frequency is reduced, and the converter consumes 30A of current, making it ideal for battery-operated applications. The output voltage is programmable from VIN to as low as 0.6V. Power devices are sized for 12 250mA current capability while maintaining over 90% efficiency at full load. Light load efficiency is maintained at greater than 80% down to 1mA of load current. A high-DC gain error amplifier with internal compensation controls the output. It provides excellent transient response and load/line regulation. Under-Voltage Lockout The AAT2556 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. If the input voltage of the step-down converter drops below UVLO, the internal circuit will shut down. Protection Circuitry Over-Voltage Protection An over-voltage protection event is defined as a condition where the voltage on the BAT pin exceeds the over-voltage protection threshold (VOVP). 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. www.analogictech.com 2556.2009.08.1.3 PRODUCT DATASHEET AAT2556 SystemPowerTM Battery Charger and Step-Down Converter for Portable Applications Current Limit, Over-Temperature Protection 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. For overload conditions, the peak input current is limited at the step-down converter. As load impedance decreases and the output voltage falls closer to zero, more power is dissipated internally, which causes the internal die temperature to rise. In this case, the thermal protection circuit completely disables switching, which protects the device from damage. 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. Once the internal die temperature falls below the thermal limit, normal charging operation will resume. Pre-conditioning continues until the battery voltage reaches VMIN. At this point, the charger begins constantcurrent 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 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. Control Loop The AAT2556 contains a compact, current mode stepdown DC/DC controller. The current through the P-channel MOSFET (high side) is sensed for current loop control, as well as short-circuit and overload protection. A fixed slope compensation signal is added to the sensed current to maintain stability for duty cycles greater than 50%. The peak current mode loop appears as a voltageprogrammed current source in parallel with the output capacitor. The output of the voltage error amplifier programs the current mode loop for the necessary peak switch current to force a constant output voltage for all load and line conditions. Internal loop compensation terminates the transconductance voltage error amplifier output. The error amplifier reference is fixed at 0.6V. 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. 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 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. 2556.2009.08.1.3 www.analogictech.com 13 PRODUCT DATASHEET AAT2556 SystemPowerTM Battery Charger and Step-Down Converter for Portable Applications 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 ADP > VBAT No Voltage Phase Test IBAT > ITERM No Charge Completed 14 www.analogictech.com 2556.2009.08.1.3 PRODUCT DATASHEET AAT2556 SystemPowerTM Battery Charger and Step-Down Converter for Portable Applications Application Information Normal ICHARGE (mA) Set Resistor Value R2 (k) 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 Soft Start / Enable 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. Pulling EN_BUCK to logic low forces the converter in a low power, non-switching state, and it consumes less than 1A of quiescent current. Connecting it to logic high enables the converter and resumes normal operation. 1000 100 10 1 Adapter or USB Power Input 1 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. 2556.2009.08.1.3 Table 1: RSET Values. ICH (mA) The step-down converter features a soft start that limits the inrush current and eliminates output voltage overshoot during startup. The circuit is designed to increase the inductor current limit in discrete steps when the input voltage or enable input is applied. Typical start up time is 100s. 10 100 1000 RSET (k ) Figure 2: Constant Charging Current vs. Set Resistor Values. Charge Status Output The AAT2556 provides battery charge status via a status pin. This pin is internally connected to an N-channel open drain MOSFET, which can be used to drive an external LED. The status pin can indicate several conditions, as shown in Table 2. Event Description No battery charging activity Battery charging via adapter or USB port Charging completed www.analogictech.com Status OFF ON OFF Table 2: LED Status Indicator. 15 PRODUCT DATASHEET AAT2556 Battery Charger and Step-Down Converter for Portable Applications 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 lowcost green or red LEDs. It is not recommended to exceed 8mA for driving an individual status LED. Figure 3 shows the relationship of maximum power dissipation and ambient temperature of the AAT2556. 3000 2500 PD(MAX) (mW) SystemPowerTM 2000 1500 1000 The required ballast resistor values can be estimated using the following formulas: 500 0 0 (VADP - VF(LED)) R 1= ILED 40 60 80 100 120 TA (C) Figure 3: Maximum Power Dissipation. Example: (5.5V - 2.0V) = 1.75k R1 = 2mA Note: Red LED forward voltage (VF) is typically 2.0V @ 2mA. Thermal Considerations The AAT2556 is offered in a TDFN33-12 package which can provide up to 2W of power dissipation when it is properly bonded to a printed circuit board and has a maximum thermal resistance of 50C/W. Many considerations should be taken into account when designing the printed circuit board layout, as well as the placement of the charger IC package in proximity to other heat generating devices in a given application design. The ambient temperature around the 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. Next, the power dissipation of the battery charger can be calculated by the following equation: PD = [(VADP - VBAT) * ICH + (VADP * IOP)] Where: 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] 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. First, the maximum power dissipation for a given situation should be calculated: PD(MAX) = ICH(MAX) = (PD(MAX) - VIN * IOP) VIN - VBAT (TJ(MAX) - TA) - V * I IN OP JA ICH(MAX) = VIN - VBAT (TJ(MAX) - TA) JA Where: PD(MAX) = Maximum Power Dissipation (W) JA = Package Thermal Resistance (C/W) TJ(MAX) = Maximum Device Junction Temperature (C) [135C] TA = Ambient Temperature (C) 16 20 In general, the worst condition is the greatest voltage drop across the IC, when battery voltage is charged up to the preconditioning voltage threshold. Figure 4 shows the maximum charge current in different ambient temperatures. www.analogictech.com 2556.2009.08.1.3 PRODUCT DATASHEET AAT2556 SystemPowerTM Battery Charger and Step-Down Converter for Portable Applications Capacitor Selection 500 ICC(MAX) (mA) 400 TA = 60C 300 TA = 85C 200 100 0 4.25 4.5 4.75 5 5.25 5.5 5.75 6 6.25 6.5 6.75 VIN (V) Figure 4: Maximum Charging Current Before Thermal Cycling Becomes Active. There are three types of losses associated with the stepdown converter: switching losses, conduction losses, and quiescent current losses. Conduction losses are associated with the RDS(ON) characteristics of the power output switching devices. Switching losses are dominated by the gate charge of the power output switching devices. At full load, assuming continuous conduction mode (CCM), a simplified form of the losses is given by: PTOTAL = Battery Charger Input Capacitor (C1) In general, it is good design practice to place a decoupling capacitor between the ADP pin and GND. An input capacitor in the range of 1F to 22F is recommended. If the source supply is unregulated, it may be necessary to increase the capacitance to keep the input voltage above the under-voltage lockout threshold during device enable and when battery charging is initiated. If the adapter input is to be used in a system with an external power supply source, such as a typical AC-to-DC wall adapter, then a CIN capacitor in the range of 10F should be used. A larger input capacitor in this application will minimize switching or power transient effects when the power supply is "hot plugged" in. Step-Down Converter Input Capacitor (C3) Select a 4.7F to 10F X7R or X5R ceramic capacitor for the input. To estimate the required input capacitor size, determine the acceptable input ripple level (VPP) and solve for CIN. The calculated value varies with input voltage and is a maximum when VIN is double the output voltage. IO2 * (RDSON(H) * VO + RDSON(L) * [VIN - VO]) CIN = VIN + (tsw * FS * IO + IQ) * VIN PTOTAL = IO2 * RDSON(H) + IQ * VIN Always examine the ceramic capacitor DC voltage coefficient characteristics when selecting the proper value. For example, the capacitance of a 10F, 6.3V, X5R ceramic capacitor with 5.0V DC applied is actually about 6F. The maximum input capacitor RMS current is: Since RDS(ON), quiescent current, and switching losses all vary with input voltage, the total losses should be investigated over the complete input voltage range. Given the total losses, the maximum junction temperature can be derived from the JA for the TDFN33-12 package which is 50C/W. VO V * 1- O = VIN VIN D * (1 - D) = 0.52 = 1 2 The input capacitor RMS ripple current varies with the input and output voltage and will always be less than or equal to half of the total DC load current. TJ(MAX) = PTOTAL * JA + TAMB 2556.2009.08.1.3 VPP - ESR * FS IO VO V 1 * 1 - O = for VIN = 2 * VO VIN VIN 4 1 CIN(MIN) = VPP - ESR * 4 * FS IO IQ is the step-down converter quiescent current. The term tsw is used to estimate the full load step-down converter switching losses. For the condition where the step-down converter is in dropout at 100% duty cycle, the total device dissipation reduces to: V VO * 1- O VIN VIN IRMS = IO * www.analogictech.com VO V * 1- O VIN VIN 17 PRODUCT DATASHEET AAT2556 SystemPowerTM Battery Charger and Step-Down Converter for Portable Applications for VIN = 2 * VO IRMS(MAX) = VO IO 2 V * 1- O The term VIN VIN appears in both the input voltage ripple and input capacitor RMS current equations and is a maximum when VO is twice VIN. This is why the input voltage ripple and the input capacitor RMS current ripple are a maximum at 50% duty cycle. The input capacitor provides a low impedance loop for the edges of pulsed current drawn by the step-down converter. Low ESR/ESL X7R and X5R ceramic capacitors are ideal for this function. To minimize stray inductance, the capacitor should be placed as closely as possible to the IC. This keeps the high frequency content of the input current localized, minimizing EMI and input voltage ripple. The proper placement of the input capacitor (C3) can be seen in the evaluation board layout in Figure 6. A laboratory test set-up typically consists of two long wires running from the bench power supply to the evaluation board input voltage pins. The inductance of these wires, along with the low-ESR ceramic input capacitor, can create a high Q network that may affect converter performance. This problem often becomes apparent in the form of excessive ringing in the output voltage during load transients. Errors in the loop phase and gain measurements can also result. Since the inductance of a short PCB trace feeding the input voltage is significantly lower than the power leads from the bench power supply, most applications do not exhibit this problem. In applications where the input power source lead inductance cannot be reduced to a level that does not affect the converter performance, a high ESR tantalum or aluminum electrolytic capacitor should be placed in parallel with the low ESR, ESL bypass ceramic capacitor. This dampens the high Q network and stabilizes the system. Battery Charger Output Capacitor (C2) The AAT2556 only requires a 1F ceramic capacitor on the BAT pin to maintain circuit stability. This value should be increased to 10F or more if the battery connection is made any distance from the charger output. If the 18 AAT2556 is to be used in applications where the battery can be removed from the charger, such as with desktop charging cradles, an output capacitor greater than 10F may be required to prevent the device from cycling on and off when no battery is present. Step-Down Converter Output Capacitor (C4) The output capacitor limits the output ripple and provides holdup during large load transitions. A 4.7F to 10F X5R or X7R ceramic capacitor typically provides sufficient bulk capacitance to stabilize the output during large load transitions and has the ESR and ESL characteristics necessary for low output ripple. For enhanced transient response and low temperature operation applications, a 10F (X5R, X7R) ceramic capacitor is recommended to stabilize extreme pulsed load conditions. The output voltage droop due to a load transient is dominated by the capacitance of the ceramic output capacitor. During a step increase in load current, the ceramic output capacitor alone supplies the load current until the loop responds. Within two or three switching cycles, the loop responds and the inductor current increases to match the load current demand. The relationship of the output voltage droop during the three switching cycles to the output capacitance can be estimated by: COUT = 3 * ILOAD VDROOP * FS Once the average inductor current increases to the DC load level, the output voltage recovers. The above equation establishes a limit on the minimum value for the output capacitor with respect to load transients. The internal voltage loop compensation also limits the minimum output capacitor value to 4.7F. This is due to its effect on the loop crossover frequency (bandwidth), phase margin, and gain margin. Increased output capacitance will reduce the crossover frequency with greater phase margin. The maximum output capacitor RMS ripple current is given by: IRMS(MAX) = www.analogictech.com 1 VOUT * (VIN(MAX) - VOUT) L * FS * VIN(MAX) 2* 3 * 2556.2009.08.1.3 PRODUCT DATASHEET AAT2556 SystemPowerTM Battery Charger and Step-Down Converter for Portable Applications Dissipation due to the RMS current in the ceramic output capacitor ESR is typically minimal, resulting in less than a few degrees rise in hot-spot temperature. Output Voltage (V) L1 (H) 1.0 1.2 1.5 1.8 2.5 3.0 3.3 1.5 2.2 2.7 3.0/3.3 3.9/4.2 4.7 5.6 Inductor Selection The step-down converter uses peak current mode control with slope compensation to maintain stability for duty cycles greater than 50%. The output inductor value must be selected so the inductor current down slope meets the internal slope compensation requirements. The internal slope compensation for the AAT2556 is 0.45A/sec. This equates to a slope compensation that is 75% of the inductor current down slope for a 1.8V output and 3.0H inductor. m= L= 0.75 VO 0.75 1.8V A = = 0.45 L 3.0H sec 0.75 VO = m = 1.67 sec 0.75 VO 1.67 A VO A 0.45A sec sec 3.0V = 5.0H A Adjustable Output Resistor Selection Resistors R3 and R4 of Figure 5 program the output to regulate at a voltage higher than 0.6V. To limit the bias current required for the external feedback resistor string while maintaining good noise immunity, the suggested value for R4 is 59k. Decreased resistor values are necessary to maintain noise immunity on the FB pin, resulting in increased quiescent current. Table 4 summarizes the resistor values for various output voltages. VOUT 3.3V R3 = V -1 * R4 = 0.6V - 1 * 59k = 267k REF For most designs, the step-down converter operates with an inductor value of 1H to 4.7H. Table 3 displays inductor values for the AAT2556 with different output voltage options. Manufacturer's specifications list both the inductor DC current rating, which is a thermal limitation, and the peak current rating, which is determined by the saturation characteristics. The inductor should not show any appreciable saturation under normal load conditions. Some inductors may meet the peak and average current ratings yet result in excessive losses due to a high DCR. Always consider the losses associated with the DCR and its effect on the total converter efficiency when selecting an inductor. The 3.0H CDRH2D09 series inductor selected from Sumida has a 150m DCR and a 470mA DC current rating. At full load, the inductor DC loss is 9.375mW which gives a 2.08% loss in efficiency for a 250mA, 1.8V output. 2556.2009.08.1.3 Table 3: Inductor Values. With enhanced transient response for extreme pulsed load application, an external feed-forward capacitor (C5 in Figure 5) can be added. R4 = 59k R4 = 221k VOUT (V) R3 (k) R3 (k) 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.8 1.85 2.0 2.5 3.3 19.6 29.4 39.2 49.9 59.0 68.1 78.7 88.7 118 124 137 187 267 75 113 150 187 221 261 301 332 442 464 523 715 1000 Table 4: Adjustable Resistor Values For Step-Down Converter. www.analogictech.com 19 PRODUCT DATASHEET AAT2556 SystemPowerTM Battery Charger and Step-Down Converter for Portable Applications Printed Circuit Board Layout Considerations 3. For the best results, it is recommended to physically place the battery pack as close as possible to the AAT2556 BAT pin. To minimize voltage drops on the PCB, keep the high current carrying traces adequately wide. Refer to the AAT2556 evaluation board for a good layout example (see Figures 6 and 7). The following guidelines should be used to help ensure a proper layout. 1. 2. 20 The input capacitors (C1, C3) should connect as closely as possible to ADP (Pin 9) and VIN (Pin 12). C4 and L1 should be connected as closely as possible. The connection of L1 to the LX pin should be as short as possible. Do not make the node small by using narrow trace. The trace should be kept wide, direct, and short. 4. 5. The feedback pin (Pin 1) should be separate from any power trace and connect as closely as possible to the load point. Sensing along a high-current load trace will degrade DC load regulation. Feedback resistors should be placed as closely as possible to the FB pin (Pin 1) to minimize the length of the high impedance feedback trace. If possible, they should also be placed away from the LX (switching node) and inductor to improve noise immunity. The resistance of the trace from the load return to PGND (Pin 10) and GND (Pin 2) should be kept to a minimum. This will help to minimize any error in DC regulation due to differences in the potential of the internal signal ground and the power ground. A high density, small footprint layout can be achieved using an inexpensive, miniature, non-shielded, high DCR inductor. www.analogictech.com 2556.2009.08.1.3 PRODUCT DATASHEET AAT2556 SystemPowerTM Battery Charger and Step-Down Converter for Portable Applications JP4 1 2 3 BAT R4 59k C2 2.2F 1 2 3 4 5 6 L1 U1 AAT2556 FB VIN GND LX EN_BUCK GND EN_BAT ADP ISET GND BAT STAT VOUT C4 4.7F 3H 12 11 10 9 8 7 R2 8.06K R1 1K D1 JP1 0 C1 10F RED LED 1 2 1 2 3 JP3 VOUT 4.7uF C5 100pF ADP C3 VIN R3 118k Buck Input Enable_Buck JP2 Enable_Bat Figure 5: AAT2556 Evaluation Board Schematic. Figure 6: AAT2556 Evaluation Board Top Side Layout. 2556.2009.08.1.3 Figure 7: AAT2556 Evaluation Board Bottom Side Layout. www.analogictech.com 21 PRODUCT DATASHEET AAT2556 SystemPowerTM Component Battery Charger and Step-Down Converter for Portable Applications Part Number U1 AAT2556IWP-T1 C1 C2 C3, C4 C5 L1 R1 R2 R3 R4 JP1 JP2, JP3, JP4 D1 ECJ-1VB0J106M GRM185B30J225KE25D GRM188R60J475KE19B GRM1886R1H101JZ01J CDRH2D09-3R0 Chip Resistor Chip Resistor Chip Resistor Chip Resistor Chip Resistor PRPN401PAEN CMD15-21SRC/TR8 Description Battery Charger and Step-Down Converter for Portable Applications; TDFN33-12 Package Cer 10F 10V 20% X5R 0603 Cer 2.2F 6.3V 10% X7R 0603 Cer 4.7F 6.3V 10% X7R 0603 Cer 100pF 50V 5% R2H 0603 Shielded SMD, 3.0H, 150m, 3x3x1mm 1K, 5%, 1/4W; 0603 8.06K, 1%, 1/4W; 0603 118K, 1%, 1/4W; 0603 59K, 1%, 1/4W; 0603 0, 5%, 1/4W; 0603 Connecting Header, 2mm Zip Red LED; 1206 Manufacturer AnalogicTech Panasonic - ECG Murata Murata Murata Sumida Vishay Vishay Vishay Vishay Vishay Sullins Electronics Chicago Miniature Lamp Table 5: AAT2556 Evaluation Board Component Listing. 22 www.analogictech.com 2556.2009.08.1.3 PRODUCT DATASHEET AAT2556 SystemPowerTM Battery Charger and Step-Down Converter for Portable Applications Step-Down Converter Design Example Specifications VO = 1.8V @ 250mA, Pulsed Load ILOAD = 200mA VIN = 2.7V to 4.2V (3.6V nominal) FS = 1.5MHz TAMB = 85C 1.8V Output Inductor L1 = 1.67 sec sec VO2 = 1.67 1.8V = 3H (use 3.0H; see Table 3) A A For Sumida inductor CDRH2D09-3R0, 3.0H, DCR = 150m. IL1 = VO V 1.8V 1.8V 1- O = 1= 228mA L1 FS VIN 3.0H 1.5MHz 4.2V IPKL1 = IO + IL1 = 250mA + 114mA = 364mA 2 PL1 = IO2 DCR = 250mA2 150m = 9.375mW 1.8V Output Capacitor VDROOP = 0.1V COUT = 3 * ILOAD 3 * 0.2A = = 4F; use 4.7F VDROOP * FS 0.1V * 1.5MHz IRMS = (VO) * (VIN(MAX) - VO) 1 1.8V * (4.2V - 1.8V) * = 66mArms = L1 * FS * VIN(MAX) 2 * 3 3.0H * 1.5MHz * 4.2V 2* 3 1 * Pesr = esr * IRMS2 = 5m * (66mA)2 = 21.8W 2556.2009.08.1.3 www.analogictech.com 23 PRODUCT DATASHEET AAT2556 SystemPowerTM Battery Charger and Step-Down Converter for Portable Applications Input Capacitor Input Ripple VPP = 25mV CIN = IRMS = VPP IO 1 1 = = 1.38F (use 4.7F) 25mV - 5m * 4 * 1.5MHz - ESR * 4 * FS 0.2A IO = 0.1Arms 2 P = esr * IRMS2 = 5m * (0.1A)2 = 0.05mW AAT2556 Losses PTOTAL = IO2 * (RDSON(H) * VO + RDSON(L) * [VIN -VO]) VIN + (tsw * FS * IO + IQ) * VIN = 0.22 * (0.59 * 1.8V + 0.42 * [4.2V - 1.8V]) 4.2V + (5ns * 1.5MHz * 0.2A + 30A) * 4.2V = 26.14mW TJ(MAX) = TAMB + JA * PLOSS = 85C + (50C/W) * 26.14mW = 86.3C 24 www.analogictech.com 2556.2009.08.1.3 PRODUCT DATASHEET AAT2556 SystemPowerTM Battery Charger and Step-Down Converter for Portable Applications Output Voltage VOUT (V) R4 = 59k R3 (k) R4 = 221k1 R3 (k) L1 (H) 0.6 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.8 1.85 2.0 2.5 3.3 -- 19.6 29.4 39.2 49.9 59.0 68.1 78.7 88.7 118 124 137 187 267 -- 75 113 150 187 221 261 301 332 442 464 523 715 1000 1.5 1.5 1.5 1.5 1.5 1.5 1.5 2.2 2.7 3.0/3.3 3.0/3.3 3.0/3.3 3.9/4.2 5.6 2 Table 6: Step-Down Converter Component Values. Manufacturer Part Number Inductance (H) Max DC Current (mA) DCR (m) Size (mm) LxWxH Type Sumida Sumida Sumida Sumida Sumida Sumida Sumida Sumida Sumida Sumida Sumida Taiyo Yuden Taiyo Yuden Taiyo Yuden Taiyo Yuden FDK FDK FDK FDK CDRH2D09-1R5 CDRH2D09-2R2 CDRH2D09-2R5 CDRH2D09-3R0 CDRH2D09-3R9 CDRH2D09-4R7 CDRH2D09-5R6 CDRH2D11-1R5 CDRH2D11-2R2 CDRH2D11-3R3 CDRH2D11-4R7 NR3010 NR3010 NR3010 NR3010 MIPWT3226D-1R5 MIPWT3226D-2R2 MIPWT3226D-3R0 MIPWT3226D-4R2 1.5 2.2 2.5 3 3.9 4.7 5.6 1.5 2.2 3.3 4.7 1.5 2.2 3.3 4.7 1.5 2.2 3 4.2 730 600 530 470 450 410 370 900 780 600 500 1200 1100 870 750 1200 1100 1000 900 88 115 135 150 180 230 260 54 78 98 135 80 95 140 190 90 100 120 140 3.0x3.0x1.0 3.0x3.0x1.0 3.0x3.0x1.0 3.0x3.0x1.0 3.0x3.0x1.0 3.0x3.0x1.0 3.0x3.0x1.0 3.2x3.2x1.2 3.2x3.2x1.2 3.2x3.2x1.2 3.2x3.2x1.2 3.0x3.0x1.0 3.0x3.0x1.0 3.0x3.0x1.0 3.0x3.0x1.0 3.2x2.6x0.8 3.2x2.6x0.8 3.2x2.6x0.8 3.2x2.6x0.8 Shielded Shielded Shielded Shielded Shielded Shielded Shielded Shielded Shielded Shielded Shielded Shielded Shielded Shielded Shielded Chip shielded Chip shielded Chip shielded Chip shielded Table 7: Suggested Inductors and Suppliers. Manufacturer Part Number Value (F) Voltage Rating Temp. Co. Case Size Murata Murata GRM118R60J475KE19B GRM188R60J106ME47D 4.7 10 6.3 6.3 X5R X5R 0603 0603 Table 8: Surface Mount Capacitors. 1. For reduced quiescent current, R4 = 221kW. 2. R4 is opened, R3 is shorted. 2556.2009.08.1.3 www.analogictech.com 25 PRODUCT DATASHEET AAT2556 SystemPowerTM Battery Charger and Step-Down Converter for Portable Applications Ordering Information Package Marking1 Part Number (Tape and Reel)2, 3 TDFN33-12 SPXYY AAT2556IWP-CA-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/aboutus/quality.php. Legend Voltage Adjustable (0.6V) 0.9 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 Code A B 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. 3. Available exclusively outside of the United States and its territories. 26 www.analogictech.com 2556.2009.08.1.3 PRODUCT DATASHEET AAT2556 SystemPowerTM Battery Charger and Step-Down Converter for Portable Applications Package Information TDFN33-121 Index Area 0.43 0.05 0.1 REF C0.3 0.45 0.05 2.40 0.05 3.00 0.05 Detail "A" 3.00 0.05 1.70 0.05 Top View Bottom View 0.23 0.05 Pin 1 Indicator (optional) 0.05 0.05 0.23 0.05 0.75 0.05 Detail "A" Side View All dimensions in millimeters 1. The leadless package family, which includes QFN, TQFN, DFN, TDFN and STDFN, has exposed copper (unplated) at the end of the lead terminals due to the manufacturing process. A solder fillet at the exposed copper edge cannot be guaranteed and is not required to ensure a proper bottom solder connection. Advanced Analogic Technologies, Inc. 3230 Scott Boulevard, Santa Clara, CA 95054 Phone (408) 737-4600 Fax (408) 737-4611 (c) Advanced Analogic Technologies, Inc. AnalogicTech cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in an AnalogicTech product. No circuit patent licenses, copyrights, mask work rights, or other intellectual property rights are implied. AnalogicTech reserves the right to make changes to their products or specifications or to discontinue any product or service without notice. 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. 2556.2009.08.1.3 www.analogictech.com 27