19-4279; Rev 0; 3/09 EVALUATION KIT AVAILABLE 28V Dual Input Linear Li+ Battery Chargers with Battery Detection and Overvoltage-Protected Output Applications Cellular and Cordless Phones Features CCCV, Thermally Regulated Linear One-Cell Li+ Battery Charger No External MOSFET, Reverse Blocking Diode, or Current-Sense Resistor Programmable Fast-Charge Currents (1ARMS max) Programmable Top-Off Current Threshold Input Overvoltage Protected 4.7V Output (SAFEOUT) from IN Input Overvoltage Protected 4.7V Output (SAFEUSB) from USB Proprietary Die Temperature Regulation Control (+115C) 4.25V to 28V Input Voltage Range with Input Overvoltage Protection Above +7.5V Low-Dropout Voltage (300mV at 500mA) Input Power-Source Detection Output (POK), Charge Status Output (CHG), Charge-Enable Input (EN) Output for Autobooting (ABO, MAX8844Z) Output for Autobooting (ABO, MAX8844Y) Tiny 3mm x 3mm, 14-Pin TDFN Package, 0.8mm Height (max) Ordering Information PART PINPACKAGE TOP MARK ABO ACTIVE STATE MAX8844ZETD+ 14 TDFN-EP* AEK Active high MAX8844YETD+ 14 TDFN-EP* AEN Active low +Denotes a lead(Pb)-free/RoHS-compliant package. *EP = Exposed pad. Note: All devices are specified over the -40C to +85C operating temperature range. USB Appliances Smart Phones and PDAs Charging Cradles and Docks Digital Still Cameras Bluetooth(R) Equipment Typical Operating Circuit and Pin Configuration appear at end of data sheet. MP3 Players Bluetooth is a registered trademark of Bluetooth SIG. ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com. 1 MAX8844Z/MAX8844Y General Description The MAX8844Z/MAX8844Y intelligent, stand-alone constant-current, constant-voltage (CCCV), thermally regulated dual input linear chargers are designed for charging a single-cell lithium-ion (Li+) battery. The MAX8844Z/MAX8844Y integrate a current-sense circuit, MOSFET pass element, thermal-regulation circuitry, and eliminate the external reverse-blocking Schottky diode to create the simplest and smallest charging solutions for handheld equipment. The IC controls the charging sequence from the prequalification state through constant current fast-charge, top-off charge, and full-charge indication. Proprietary thermal-regulation circuitry limits the die temperature during fast-charging or when the IC is exposed to high ambient temperatures, allowing maximum charging current without damaging the IC. The MAX8844Z/MAX8844Y achieve high flexibility by providing adjustable fast-charge currents (SETI) and an adjustable top-off current threshold (MIN) through external resistors. The IC features a booting assistant circuit that distinguishes input sources and battery connection and provides an enable signal (ABO, ABO) for system booting. The ICs also integrate two input overvoltage-protected LDO outputs (SAFEOUT, SAFEUSB) for low-voltagerated USB or charger inputs in system, and a battery pack detection circuit (DETBAT) that disables the charger when the battery pack is absent. Other features include an active-low control input (EN), an active-low input power source detection output (POK), and a fully charged top-off threshold detection output (CHG). The MAX8844Z/MAX8844Y automatically select between either the USB or IN source. If both sources are present at the same time, highest priority is given to the IN source. The IN source is selected to ensure the shortest charging time for the system since it is able to deliver the highest current. The MAX8844Z/MAX8844Y accept an input supply range from 4.25V to 28V (IN and USB), but disable charging if the input voltage exceeds +7.5V to protect against unqualified or faulty AC adapters. The ICs operate over the extended temperature range (-40C to +85C) and are available in a compact 14-pin, thermally enhanced, leadfree TDFN 3mm x 3mm package (0.8mm max height). MAX8844Z/MAX8844Y 28V Dual Input Linear Li+ Battery Chargers with Battery Detection and Overvoltage-Protected Output ABSOLUTE MAXIMUM RATINGS IN, USB to GND......................................................-0.3V to +30V ABI, BATT, EN, POK, ABO, ABO, CHG, DETBAT, SETI, MIN, SAFEOUT, SAFEUSB to GND.................................................-0.3V to +6V IN to BATT Continuous Current .........................................1ARMS Continuous Power Dissipation (TA = +70C) 14 TDFN (derate 24.4mW/C above 70C) (multilayer PCB) ....................................................1951.2mW BATT Short-Circuit Duration .......................................Continuous Operating Temperature Range ...........................-40C to +85C Junction Temperature ......................................................+150C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10s) .................................+300C Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. ELECTRICAL CHARACTERISTICS (VIN = 5V or VUSB = 5V, VBATT = 4V, RPOK = 1M to BATT, EN = unconnected, RSETI = 2.8k to GND, VDETBAT = 0V, CBATT = 2.2F, TA = -40C to +85C, unless otherwise noted. Typical values are at TA = +25C.) (Note 1) PARAMETER CONDITIONS MIN TYP MAX UNITS 0 28 V 4.25 7.00 V 7.5 8.0 V Constant current charging IIN - IBATT, IBATT = 0A 0.25 0.50 Constant current charging IIN - IBATT, IBATT = 500mA 1 IN, USB Input Supply Voltage Range Input Supply Operating Voltage Range Overvoltage Lockout Trip Threshold Input Current VIN rising, 100mV hysteresis (typ) 7.0 IC disabled, V EN = 5V VIN = 4V, VBATT = 4.2V 0.23 TA = +25C 0.02 TA = +85C 0.03 mA 0.50 BATT, CHG, POK Minimum BATT Bypass Capacitance 2.2 VBATT Prequalification Threshold Voltage VBATT rising, 100mV hysteresis (typ) Battery Regulation Voltage IBATT = 0A Regulator Dropout Voltage (VIN VBATT ) VBATT = 4.1V, IBATT = 425mA BATT Input Current (Note 2) Current-Sense Amplifier Gain (IBATT to ISETI) 2 2.3 2.5 2.7 TA = 0C to +85C 4.175 4.200 4.225 TA = -40C to +85C 4.158 4.200 4.242 260 VIN = 0 to 4V, VBATT = 4.2V 5 IC disabled 3 IBATT = 500mA F TA = 0C to +85C 1120 TA = -40C to +85C 1120 _______________________________________________________________________________________ V V mV 10 A A/A 28V Dual Input Linear Li+ Battery Chargers with Battery Detection and Overvoltage-Protected Output (VIN = 5V or VUSB = 5V, VBATT = 4V, RPOK = 1M to BATT, EN = unconnected, RSETI = 2.8k to GND, VDETBAT = 0V, CBATT = 2.2F, TA = -40C to +85C, unless otherwise noted. Typical values are at TA = +25C.) (Note 1) PARAMETER Fast-Charge Current USB Fast-Charge Current CONDITIONS MIN TYP MAX TA = 0C to +85C 400 440 480 TA = -40C to +85C 375 440 505 VBATT = 3.5V, RSETI = 14k 74 88 102 MAX8844Z 332 380 418 MAX8844Y 405 450 495 VBATT = 3.5V, RSETI = 2.8k UNITS mA mA CHG Top-Off Threshold IBATT falling, battery is charged, RMIN = 1.75k (Note 3) 99 mA CHG Hysteresis IBATT rising after top-off is detected, RMIN = 1.75k 27 mA CHG Detection Delay IBATT falls below top-off threshold Prequalification Charge Current Percentage of the fast-charge current, VBATT = 2.2V, TA = 0C to +85C CHG, POK Output Low Threshold IPOK = 5mA , ICHG = 5mA CHG, POK Output High Leakage Current V POK = 5.5V, V CHG = 5.5V POK Threshold (Note 2) VIN - VBATT 4.0 6.2 10.7 ms 5 11 17 % 0.4 V TA = +25C 1 TA = +85C 0.002 VIN rising 40 VIN falling 30 A mV DETBAT, SAFEOUT, SAFEUSB DETBAT Logic Input Low Threshold 0.4 V DETBAT Logic Input High Threshold DETBAT Pullup Resistor 1.3 DETBAT to VL = 3V Minimum SAFEOUT Bypass Capacitance SAFEOUT Regulated Output ISAFEOUT = 30mA, VIN = 5V, TA = 0C to +85C 4.5 SAFEOUT Current Limit Minimum SAFEUSB Bypass Capacitance SAFEUSB Regulated Output ISAFEUSB = 30mA, VUSB = 5V, TA = 0C to +85C 4.5 SAFEUSB Current Limit 470 k 1 F 4.7 4.9 V 100 mA 1 F 4.7 4.9 100 V mA EN, ABI, ABO, ABO EN, ABI Internal Pulldown Resistor 100 EN, Logic Input Low Threshold (Note 2) 4.25V VIN 7V EN, Logic Input High Theshold (Note 2) 4.25V VIN 7V 1.3 200 400 k 0.4 V V _______________________________________________________________________________________ 3 MAX8844Z/MAX8844Y ELECTRICAL CHARACTERISTICS (continued) ELECTRICAL CHARACTERISTICS (continued) (VIN = 5V or VUSB = 5V, VBATT = 4V, RPOK = 1M to BATT, EN = unconnected, RSETI = 2.8k to GND, VDETBAT = 0V, CBATT = 2.2F, TA = -40C to +85C, unless otherwise noted. Typical values are at TA = +25C.) (Note 1) ABI Logic Input Low Threshold VBATT = 4V, VIN = 0V ABI Logic Input High Threshold VBATT = 4V, VIN = 0V ABO Output Low Threshold IABO(SINK) = 1mA ABO Output High Threshold IABO(SOURCE) = 1mA ABO Output Low Threshold Open drain, IABO(SINK) = 1mA ABO Output High Threshold Open drain, 100k pullup on BATT 0.4 1.3 V V 0.4 VBATT 0.4V V V 0.4 VBATT 0.4V THERMAL Die Temperature Regulation Threshold 115 C Note 1: Specifications are 100% production tested at TA = +25C. Limits over the operating temperature range are guaranteed by design and characterization. Note 2: The IN input supply and USB input supply are interchangeable (VIN = VUSB). See the DC and USB Power Supplies section for further details. Note 3: See the Top-Off Current Threshold Setting section for further details. Typical Operating Characteristics (VIN = 5V or VUSB = 5V, VBATT = 4V, R POK = RCHG = 200k to 5V, EN = unconnected, RSETI = 2.8k to GND, RMIN = 1.74k to GND, RDETBAT = 4.7k to GND, CBATT = 2.2F, TA = +25C, unless otherwise noted. VEN = 5V 0.5 SUPPLY CURRENT (mA) 0.8 0.6 0.7 0.6 0.5 0.4 0.3 0.2 0.4 0.3 0.2 0.1 0 0 4 8 12 16 20 INPUT VOLTAGE (V) 4 24 28 700 VIN = 5V, VUSB = 0V 600 500 400 300 VIN = 0V, VUSB = 5V 200 100 0.1 0 800 CHARGE CURRENT (mA) VEN = 0V, IBATT = 0A, VIN RISING 0.9 MAX8844 toc01 1.0 CHARGE CURRENT vs. BATTERY VOLTAGE MAX8844 toc03 DISABLED MODE SUPPLY CURRENT vs. INPUT VOLTAGE MAX8844 toc02 SUPPLY CURRENT vs. INPUT VOLTAGE SUPPLY CURRENT (mA) MAX8844Z/MAX8844Y 28V Dual Input Linear Li+ Battery Chargers with Battery Detection and Overvoltage-Protected Output 0 0 4 8 12 16 20 INPUT VOLTAGE (V) 24 28 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 BATTERY VOLTAGE (V) _______________________________________________________________________________________ 28V Dual Input Linear Li+ Battery Chargers with Battery Detection and Overvoltage-Protected Output 200 400 300 100 0 0 8 12 16 20 24 VUSB - VBATT 200 100 4 ISAFEOUT = 1mA 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 VBATT = 4V VSUPPLY RISING 0.5 0 0 28 100 200 300 400 500 600 0 4 8 12 16 20 24 INPUT VOLTAGE (V) VSUPPLY - VBATT (mV) INPUT VOLTAGE (V) SAFEOUT OUTPUT VOLTAGE vs. LOAD CURRENT SAFEUSB OUTPUT VOLTAGE vs. USB VOLTAGE SAFEUSB OUTPUT VOLTAGE vs. LOAD CURRENT 5 SAFEUSB VOLTAGE (V) 4.0 3.5 3.0 2.5 2.0 1.5 4 3 2 1.0 5.0 4.5 4.0 SAFEUSB VOLTAGE (V) 4.5 28 MAX8844 toc09 6 MAX8844 toc07 5.0 MAX8844 toc06 MAX8844 toc05 500 SAFEOUT VOLTAGE (V) 300 5.0 MAX8844 toc08 CHARGE CURRENT (mA) VIN = 0V, VUSB = 5V 0 SAFEOUT VOLTAGE (V) VIN - VBATT CHARGE CURRENT (mA) VIN = 5V, VUSB = 0V 400 600 MAX8844 toc04 600 500 SAFEOUT OUTPUT VOLTAGE vs. INPUT VOLTAGE CHARGE CURRENT vs. SUPPLY VOLTAGE HEADROOM CHARGE CURRENT vs. INPUT VOLTAGE 3.5 3.0 2.5 2.0 1.5 1.0 1 0.5 0.5 0 0 0 0 20 40 60 80 0 100 4 8 12 16 20 24 28 0 40 60 80 100 SHUTDOWN (FAST-CHARGE TO SHUTDOWN) STARTUP INTO PRECHARGE MAX8844 toc10 MAX8844 toc11 100mA/div 0 IBATT 20 LOAD CURRENT (mA) USB VOLTAGE (V) LOAD CURRENT (mA) VIN 5V/div VEN 0 5V/div 0 500mA/div IBATT 0 5V/div VIN 0 5V/div VEN 0 5V/div 5V/div VPOK VPOK 0 0 40s/div 100s/div _______________________________________________________________________________________ 5 MAX8844Z/MAX8844Y Typical Operating Characteristics (continued) (VIN = 5V or VUSB = 5V, VBATT = 4V, R POK = RCHG = 200k to 5V, EN = unconnected, RSETI = 2.8k to GND, RMIN = 1.74k to GND, RDETBAT = 4.7k to GND, CBATT = 2.2F, TA = +25C, unless otherwise noted. Typical Operating Characteristics (continued) (VIN = 5V or VUSB = 5V, VBATT = 4V, R POK = RCHG = 200k to 5V, EN = unconnected, RSETI = 2.8k to GND, RMIN = 1.74k to GND, RDETBAT = 4.7k to GND, CBATT = 2.2F, TA = +25C, unless otherwise noted. FAST-CHARGE CURRENT vs. RSETI BATTERY REGULATION ACCURACY vs. AMBIENT TEMPERATURE 0.6 0.4 0.2 0 -0.2 -0.4 -0.6 10,000 MAX8844 toc13 IBATT = 0A 0.8 FAST-CHARGE CURRENT (mA) MAX8844 toc12 1000 100 -0.8 10 -1.0 -40 -15 10 35 60 1 85 TOP-OFF THRESHOLD CURRENT vs. 1/RMIN (k) CHARGE CURRENT vs. AMBIENT TEMPERATURE 700 MAX8844 toc14 450 600 CHARGE CURRENT (mA) 400 TOP-OFF CURRENT RISING 300 250 200 150 100 RSETI (k) 500 350 10 AMBIENT TEMPERATURE (C) TOP-OFF CURRENT FALLING VBATT = 4V 500 400 300 VBATT = 3.2V 200 100 100 RSETI = 2.8k 0 50 -40 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 0.5 0.7 0.9 1.1 1.3 1.5 1.7 1.9 1/RMIN (k) -20 0 20 40 100 MAX8844 toc17 5V/div 0 5V/div VABI 0 5V/div 0 VIN 80 AUTOBOOT ENABLED BY INPUT VOLTAGE (MAX8844Z) MAX8844 toc16 VABI 60 AMBIENT TEMPERATURE (C) AUTOBOOT ENABLED BY ABI SIGNAL (MAX8844Z) 5V/div 0 VIN VBATT 5V/div 0 5V/div VBATT 5V/div 0 5V/div VABO 0 VABO 0 4s/div 6 MAX8844 toc15 BATTERY REGULATION ACCURACY (%) 1.0 TOP-OFF THRESHOLD CURRENT (mA) MAX8844Z/MAX8844Y 28V Dual Input Linear Li+ Battery Chargers with Battery Detection and Overvoltage-Protected Output 20s/div _______________________________________________________________________________________ 28V Dual Input Linear Li+ Battery Chargers with Battery Detection and Overvoltage-Protected Output PIN MAX8844Z MAX8844Y 1 1 2 2 NAME FUNCTION IN Input Supply Voltage. IN is the power supply for the SAFEOUT linear regulator and the battery charger. See the DC and USB Power Supplies section. Bypass IN to GND with a 1F or larger ceramic capacitor to improve line noise and input transient rejection. POK Active-Low, Input Voltage Status Indicator. POK is an open-drain output that asserts low when 2.35V < (VIN or VUSB) < 7V and [(VIN or VUSB) - VBATT] > 40mV. If (VIN or VUSB) > +7.5V or VBATT > (VIN or VUSB), the IC is shut down and POK becomes high impedance. Connect a pullup resistor to the microprocessor's I/O voltage when interfacing with a microprocessor logic input. 3 3 USB USB Input Supply Voltage. USB is the power supply for the SAFEUSB linear regulator and the battery charger. See the DC and USB Power Supplies section. Bypass USB to GND with a 1F or larger ceramic capacitor to improve line noise and input transient rejection. 4 4 ABI Autobooting External Input. See the Autobooting Assistant section and Table 1 for autobooting conditions. ABI is pulled to GND through an internal 200k resistor. 5 -- ABO Active-High, Autobooting Logic Output. See the Autobooting Assistant section and Table 1 for autobooting conditions. -- 5 ABO Active-Low, Autobooting Logic Output. See the Autobooting Assistant section and Table 1 for autobooting conditions. 6 6 MIN Top-Off Current Threshold Programmable Input. IMIN (mA) falling = 126V/RMIN (k) + 27 (mA). Charge-Current Program and Fast-Charge Current Monitor. Output current from SETI is 1120A per ampere of battery charging current. Set the charging current by connecting a resistor (RSETI in Figure 3) from SETI to GND. IFAST-CHARGE = 1250V/RSETI. To configure the MAX8844Z/MAX8844Y as a USB charger, see Figure 5. 7 7 SETI 8 8 DETBAT Battery Pack ID Resistor Detection Input. If DETBAT is pulled low through a pulldown resistor less than 51k, the charger is enabled. If DETBAT is left unconnected, the charger is disabled. 9 9 CHG Active-Low, Charging Indicator. CHG is an open-drain output that is pulled low once charging begins. CHG is high impedance when the battery current drops below MIN, or when the IC is disabled. Connect a pullup resistor to the microprocessor's I/O voltage when interfacing with a microprocessor logic input. 10 10 EN Active-Low, Logic-Level Enable Input. Drive EN high to disable charger. Drive EN low or leave unconnected for normal operation. EN has an internal 200k pulldown resistor. 11 11 GND Ground. Connect GND and the exposed pad to a large copper ground plane for maximum power dissipation. Connect GND to the exposed pad directly under the IC. 12 12 BATT Li+ Battery Connection. Bypass BATT to GND with a 2.2F ceramic capacitor. 13 13 SAFEUSB 4.7V Regulated LDO Output with Input Overvoltage Protection. Bypass SAFEUSB to GND with a 1F or larger ceramic capacitor. SAFEUSB can be used to supply lowvoltage-rated USB systems. _______________________________________________________________________________________ 7 MAX8844Z/MAX8844Y Pin Description MAX8844Z/MAX8844Y 28V Dual Input Linear Li+ Battery Chargers with Battery Detection and Overvoltage-Protected Output Pin Description (continued) PIN NAME MAX8844Z MAX8844Y 14 14 SAFEOUT -- -- EP FUNCTION 4.7V Regulated LDO Output with Input Overvoltage Protection. Bypass SAFEOUT to GND with a 1F or larger ceramic capacitor. SAFEOUT can be used to supply lowvoltage-rated charging systems. Exposed Pad. Connect the exposed pad to a large ground plane for maximum power dissipation. Connect GND to the exposed pad directly under the IC. LINEAR REGULATOR WITH OVP SAFEUSB USB LINEAR REGULATOR WITH OVP SAFEOUT BATT IN 4.2V Li+ +115C OUTPUT DRIVER, CURRENT SENSE, AND LOGIC TEMPERATURE SENSOR DETBAT SETI VREF VREF VI/O IMINREF MIN IN/USB* CHG VIN/VUSB* OVLO VL REGULATOR POK BATT BATT POK VL VL UVLO REF ABO (MAX8844Z ONLY) LOGIC DETBAT VREF ABI REFOK 200k ABO (MAX8844Y ONLY) EN MAX8844Z MAX8844Y 200k *SEE THE DC AND USB POWER SUPPLIES SECTION. GND EP Figure 1. Functional Diagram 8 _______________________________________________________________________________________ 28V Dual Input Linear Li+ Battery Chargers with Battery Detection and Overvoltage-Protected Output The MAX8844Z/MAX8844Y chargers use voltage, current, and thermal-control loops to charge a single Li+ cell and protect the battery (Figure 1). When a Li+ battery with a cell voltage below 2.5V is inserted, the MAX8844Z/MAX8844Y chargers enter a prequalification stage where they precharge that cell with 10% of the user-programmed fast-charge current (Figure 2). The CHG indicator is driven low to indicate entry into the prequalification state. When the battery voltage exceeds 2.5V, the charger soft-starts as it enters the fast-charge stage. The fast-charge current level is programmed through a resistor from SETI to GND. As the battery voltage approaches 4.2V, the battery current is reduced. If the battery current drops to less than the top-off current threshold set by R MIN , the charger enters top-off mode and the CHG indicator goes high impedance, signaling that the battery is fully charged. Overvoltage Protected Output (SAFEUSB) SAFEUSB is a linear regulator that provides an output voltage of 4.7V and can be used to supply low voltage rated USB systems. The SAFEUSB linear regulator turns on when VUSB 4.25V regardless of EN and is disabled when VUSB is greater than the overvoltage threshold (7.5V typ). Battery Pack Detection Input (DETBAT) DETBAT is a battery pack ID resistor detector that enables the battery charger if pulled low through a resistor that is less than 51k. If DETBAT is left unconnected or the pulldown resistor is 51k or greater, the battery charger is disabled. POK Output The open-drain POK output asserts low when 2.35V (VIN or VUSB) 7V, [(VIN or VUSB) - VBATT] 40mV (typ V IN or V USB rising), and DETBET is pulled low through a resistor that is less than 51k. POK is high Overvoltage-Protected Output (SAFEOUT) SAFEOUT is a linear regulator that provides an output voltage of 4.7V and can be used to supply low-voltagerated charging systems. The SAFEOUT linear regulator ASYNCHRONOUS FROM ANYWHERE VIN* > 7.5V, OR (VIN* - VBATT) < 30mV, OR THERMAL SHUTDOWN, OR IC DISABLED SHUTDOWN CHARGER = DISABLED CHG = HIGH-Z VBATT < 2.5V (VIN* - VBATT) < 30mV PRECHARGE 10% OF IFAST-CHARGE CHG = LOW VIN* < 7.5V, AND (VIN* - VBATT) 40mV, AND IC ENABLED ANY CHARGING STATE VBATT < 2.4V VIN* > 7V, OR (VIN* - VBATT) < 30mV, OR IC DISABLED DIE TEMPERATURE > +115C CHARGING CURRENT REDUCTION CHARGING CURRENT IS REDUCED AS NECESSARY VBATT 2.5V DIE TEMPERATURE +115C IBATT > 248V/RMIN (k) - 16mA FAST-CHARGE CONSTANT-CURRENT CHARGE 100% OF IFAST-CHARGE CHG = LOW TOP-OFF 4.2 VOLTAGE REGULATION CHG = HIGH-Z RETURN TO CHARGING STATE IBATT IMIN FOR 6.2ms (typ) OR LONGER *SEE THE DC AND USB POWER SUPPLIES SECTION. Figure 2. Charge-State Diagram _______________________________________________________________________________________ 9 MAX8844Z/MAX8844Y turns on when VIN 4.25V regardless of EN and is disabled when VIN is greater than the overvoltage threshold (7.5V typ). Detailed Description MAX8844Z/MAX8844Y 28V Dual Input Linear Li+ Battery Chargers with Battery Detection and Overvoltage-Protected Output Table 1. Autobooting Output States ABI BATT POK CHARGER STATE ABO (MAX8844Z) ABO (MAX8844Y) Low Present High-Z Shutdown Low High-Z High Present High-Z Shutdown High Low Low Not present Low CC/CV mode High High-Z Low Present Low Fast-charge/top-off High High-Z High Present Low Fast-charge/top-off High Low Note: Present indicates that VBATT 2.0V and Not Present indicates that the battery is not connected. impedance during shutdown. When interfacing with a microprocessor logic input, a pullup resistor to the microprocessor's I/O voltage may be required. If DETBAT is not used, connect DETBAT to GND for normal operation. 4) is required for ESD protection and noise filtering. If ABI is supplied by a system's internal GPIO, or logic, the RC filter is not required. For the MAX8844Y, the output ABO is only dependent on the state of ABI (Table 1). Autobooting Assistant The MAX8844Z/MAX8844Y contain an autobooting assistant circuit that generates an enable signal for system booting (ABO, ABO). For the MAX8844Z, the booting assistant functions as an internal OR gate (Figure 1). The first input is dependent on the input supply voltage (VIN or VUSB) and DETBAT while the second input is an external signal applied to ABI. The first input (POK) is driven high once DETBAT is pulled low through a resistor less than 51k, 2.35V (VIN or VUSB) 7V, and [(VIN or VUSB) - VBATT] 40mV (typ VIN rising). The second input signal (ABI) is driven by an external source (Table 1). ABI enables an autoboot signal when a battery is connected at BATT and is independent of POK. If POK is pulled low, the booting assistant always drives ABO high regardless of ABI. ABI is pulled to GND through an internal 200k resistor. If ABI is supplied from an outside exposed pin, an RC filter (Figure CHG Charge Indicator Output CHG is an open-drain output that indicates charge status. Table 2 describes the state of CHG during different stages of operation. CHG is suitable for driving a charge indication LED. If the MAX8844Z/MAX8844Y are used in conjunction with a microprocessor, a pullup resistor to the logic I/O voltage allows CHG to indicate charge status to the microprocessor instead of driving an LED. Thermal Regulation The thermal-regulation loop limits the MAX8844Z/ MAX8844Y die temperatures to +115C by reducing the charge current as necessary. This feature not only protects the IC from overheating, but also allows a higher charge current without risking damage to the system. Table 2. CHG States EN High VIN* VBATT IBATT CHG STATE 0 High-Z Disabled 0 High-Z Shutdown Low Precharge X X > 7.5V X X > VIN* - 30mV Low 4.25V VIN* 7.5V < 2.4V 10% of IFAST-CHARGE Low 4.25V VIN* 7.5V 2.5V 100% of IFAST-CHARGE Low Fast-charge Low 4.25V VIN* 7.5V 4.2V < IMIN High-Z Top-off Low X = Don't care. *VIN and VUSB are interchangeable. See the DC and USB Power Supplies section. I FAST-CHARGE is reduced as necessary to prevent the die temperature from exceeding +115C. 10 ______________________________________________________________________________________ 28V Dual Input Linear Li+ Battery Chargers with Battery Detection and Overvoltage-Protected Output Top-Off Current Threshold Setting The top-off current threshold is programmed by an external resistor connected from MIN to GND (RMIN). Use the following equation to determine the top-off current (IMIN): IMIN (falling) = 126V/RMIN (k) + 27mA Soft-Start The soft-start algorithm activates when entering fastcharge mode. When the prequalification state is complete (V BATT exceeds +2.5V), the charging current ramps up in 250s to the full charging current. This reduces the inrush current demand on the input supply. Applications Information Fast-Charge Current Setting The maximum charging current is programmed by an external resistor connected from SETI to GND (RSETI). Use the following equation to determine the fast-charge current (IFAST-CHARGE): IFAST-CHARGE = 1250V RSETI where IFAST-CHARGE is in amps and RSETI is in ohms. RSETI must always be 1.25k or higher due to the continuous charging current limit of 1ARMS. IMIN (rising) = 248V/RMIN (k) - 16mA where IMIN is in mA and RMIN is in k. Use RMIN 2.2k. Capacitor Selection Connect a ceramic capacitor from BATT to GND for proper stability. Use a 2.2F ceramic capacitor for most applications. Connect 1F ceramic capacitors from IN to GND and from USB to GND. A larger input capacitor can be used for high charging current to reduce input voltage ripple. Connect 1F ceramic capacitors from SAFEOUT to GND and from SAFEUSB to GND. A larger bypass capacitor for SAFEOUT and SAFEUSB can be used for optimum noise immunity. Ceramic capacitors with X5R or X7R dielectric are highly recommended due to their small size, low ESR, and small temperature coefficients. Thermal Considerations The MAX8844Z/MAX8844Y are available in a thermally enhanced TDFN package with an exposed pad. Connect the exposed pad to a large copper ground plane to provide a thermal contact between the device and the circuit board for increased power dissipation. The exposed pad transfers heat away from the device, allowing the IC to charge the battery with maximum current, while minimizing the increase in die temperature. Table 3. Input Power-Supply Selection IN USB CHARGER STATE 4.25V VIN 7V 4.25V VUSB 7V 4.25V VIN 7V Not present Not present 4.25V VUSB 7V VIN 7.5V 4.25V VUSB 7V Disabled 4.25V VIN 7V VUSB 7.5V Enabled Enabled, selects IN power supply Enabled, selects IN power supply Enabled, selects USB power supply ______________________________________________________________________________________ 11 MAX8844Z/MAX8844Y Charger Enable Input The MAX8844Z/MAX8844Y contain an active-low logic input (EN) used to enable the chargers. Drive EN low, leave unconnected, or connect to GND to enable the charge-control circuitry. Drive EN high to disable the charger-control circuitry. EN has an internal 200k pulldown resistor. MAX8844Z/MAX8844Y 28V Dual Input Linear Li+ Battery Chargers with Battery Detection and Overvoltage-Protected Output 4.2V Li+ USB BATT CUSB 1F AC ADAPTER IN GND SYSTEM CBATT 2.2F MAX8844Z CIN 1F DETBAT SAFEUSB VBUS CSAFEUSB 1F ABI SAFEOUT CSAFEOUT 1F VCHG VI/O RCHG 1M RPOK 1M SETI RSETI 2.8k MIN GPIO CHG ABO GND EP POK GPIO EN GPIO RMIN 1.75k POWER SUPPLY IF THE POWER SUPPLY IS ACTIVE-LOW ENABLED, USE THE MAX8844Y. ON Figure 3. AC Adapter Application DC and USB Power Supplies Typical Application Circuits The MAX8844Z/MAX8844Y operate from well-regulated DC sources and automatically select between both input power supply connections (Table 3). If both sources are present at the same time, highest priority is given to the IN source. The IN source is selected to ensure the shortest charging time for the system since it is able to deliver the highest current. The USB fastcharge current is fixed at 380mA (MAX8844Z) and 450mA (MAX8844Y). The full charging input voltage range for IN and USB is 4.25V to 7.5V. The device can withstand up to 28V on both inputs, IN and USB, without damage to the IC. If VIN or VUSB is greater than 7.5V, the internal overvoltage-protection circuitry disables charging until the input falls below 7.5V. The power supplies must provide at least 4.25V at the desired peak charging current and stay below 7V when unloaded. AC Adapter Application Figure 3 shows the MAX8844Z as a Li+ battery charger with an AC adapter. The MAX8844Z detects the presence of an input supply and DETBET resulting in POK pulled low. Once POK is pulled low, the autobooting assistant drives ABO high and enables the power supplies of the system to boot up. The MAX8844Z begins charging the battery when EN is low or unconnected. By monitoring CHG, the system can detect the top-off threshold and terminate the charge through EN. The MAX8844Z also provides an overvoltage-protected SAFEOUT and SAFEUSB to the system. 12 Factory System Interface Connector Application Figure 4 shows the MAX8844Z as an autoboot assistant with the factory system interface connector. The MAX8844Z detects the ABI input even though there is no input voltage available and drives ABO high to turn ______________________________________________________________________________________ 28V Dual Input Linear Li+ Battery Chargers with Battery Detection and Overvoltage-Protected Output CBATT 2.2F SYSTEM MAX8844Z IN 4.2V INTERFACE CONNECTOR GND MAX8844Z/MAX8844Y BATT USB CUSB 1F DETBAT CIN RABI 1F 10k VBUS SAFEUSB CSAFEUSB 1F ABI CABI 1F VCHG SAFEOUT CSAFEOUT 1F VI/O RCHG 1M RPOK 1M SETI RSETI 2.8k MIN GPIO CHG ABO GND EP POK GPIO EN GPIO RMIN 1.75k POWER SUPPLY IF THE POWER SUPPLY IS ACTIVE-LOW ENABLED, USE THE MAX8844Y. ON Figure 4. Factory System Interface Connector Application on power supplies to boot up the system. The configuration in Figure 4 is used for system development, testing, and calibrations in production or design stage. USB-Powered Li+ Charger The universal serial bus (USB) provides a high-speed serial communication port as well as power for the remote device. The MAX8844Z can be configured to charge a battery at the highest current possible from the host port. Figure 5 shows the MAX8844Z as a USB battery charger with the default charging current as 380mA. The MAX8844Z also provides an overvoltage protected SAFEUSB to the system. USB Connector and AC Adapter Figure 6 shows the MAX8844Z as a Li+ battery charger with an AC adapter and USB connector. The MAX8844Z detects the presence of input supplies and DETBET resulting in POK pulled low. Once POK is pulled low, the autobooting assistant drives ABO high and enables the power supplies of the system to boot up. The MAX8844Z begins charging the battery from IN source when EN is low or open. By monitoring CHG, the system can detect the top-off threshold and terminate the charge through the EN pin. The MAX8844Z provides overvoltage protected SAFEOUT and SAFEUSB to the system. Figure 7 shows the timing diagram. Recommended PCB Layout and Routing Place all bypass capacitors for IN, USB, BATT, SAFEOUT, and SAFEUSB as close to the device as possible. Connect the battery to BATT as close as possible to the device to provide accurate battery voltage sensing. Provide a large copper ground plane to allow the exposed pad to sink heat away from the device. Make all high-current traces short and wide to minimize voltage drops. A sample layout is available in the MAX8844Z evaluation kit to speed designs. ______________________________________________________________________________________ 13 MAX8844Z/MAX8844Y 28V Dual Input Linear Li+ Battery Chargers with Battery Detection and Overvoltage-Protected Output 4.2V Li+ BATT USB USB CABLE GND CBATT 2.2F CUSB 1F SYSTEM MAX8844Z IN DETBAT SAFEOUT SAFEUSB CIN 1F VBUS CSAFEOUT 1F ABI RCHG 1M GPIO CHG ABO RPOK 1M SETI RSETI 2.8k MIN VI/O GND EP POK GPIO EN GPIO RMIN 1.75k POWER SUPPLY ON IF THE POWER SUPPLY IS ACTIVE-LOW ENABLED, USE THE MAX8844Y. Figure 5. USB Battery Charger 14 ______________________________________________________________________________________ 28V Dual Input Linear Li+ Battery Chargers with Battery Detection and Overvoltage-Protected Output MAX8844Z/MAX8844Y 4.2V Li+ BATT USB CABLE GND CBATT 2.2F USB CUSB 1F MAX8844Z SYSTEM DETBAT VBUS SAFEUSB AC ADAPTER GND CSAFEUSB 1F IN CIN 1F SAFEOUT VCHG CSAFEOUT 1F VI/O ABI RCHG 1M RPOK 1M SETI RSETI 2.8k MIN GPIO CHG ABO GND EP POK GPIO EN GPIO RMIN 1.75k POWER SUPPLY IF THE POWER SUPPLY IS ACTIVE-LOW ENABLED, USE THE MAX8844Y. ON Figure 6. USB Connector and AC Adapter Application ______________________________________________________________________________________ 15 MAX8844Z/MAX8844Y 28V Dual Input Linear Li+ Battery Chargers with Battery Detection and Overvoltage-Protected Output OVP OVP POK VIN OVP OVP POK VUSB VPOK VEN VCHG VSAFEOUT = 4.7V VSAFEOUT VSAFEUSB = 4.7V VSAFEUSB TIME Figure 7. Timing Diagram 16 ______________________________________________________________________________________ 28V Dual Input Linear Li+ Battery Chargers with Battery Detection and Overvoltage-Protected Output DETBAT 4.25V TO 28V IN BATT CIN 1F CBATT 2.2F 4.2V Li+ MAX8844Z MAX8844Y 4.25V TO 28V USB SYSTEM SUPPLY CUSB 1F ABI OFF ON EN MIN CHG RMIN 1.75k POK (MAX8844Y, ABO) (MAX8844Z, ABO) SETI SAFEOUT RSETI 2.80k CSAFEOUT 1F SAFEUSB GND EP CSAFEUSB 1F Chip Information Pin Configuration SAFEUSB BATT GND EN CHG DETBAT TOP VIEW SAFEOUT PROCESS: BiCMOS 14 13 12 11 10 9 8 Package Information For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. *EXPOSED PAD 1 2 3 4 5 6 7 MIN + SETI 21-0137 ABO/ABO* T1433-2 ABI 14 TDFN-EP (3mm x 3mm) MAX8844Z MAX8844Y USB DOCUMENT NO. IN PACKAGE CODE POK PACKAGE TYPE TDFN * = ABO--MAX8844Z, ABO--MAX8844Y Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 17 (c) 2009 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc. MAX8844Z/MAX8844Y Typical Operating Circuit