19-4340; Rev 1; 9/09 KIT ATION EVALU E L B A AVAIL 28V Linear Li+ Battery Chargers with Battery Detection and Overvoltage Protected Output The MAX8845Z/MAX8845Y/MAX8845X/MAX8845W are intelligent, stand-alone constant-current, constant-voltage (CCCV), thermally regulated linear chargers designed for charging a single-cell lithium-ion (Li+) battery. The MAX8845Z/MAX8845Y/MAX8845X/MAX8845W 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 ICs control 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 ICs are exposed to high ambient temperatures, allowing maximum charging current without damaging the ICs. The MAX8845Z/MAX8845Y/MAX8845X/MAX8845W achieve high flexibility by providing adjustable fastcharge currents (SETI) and an adjustable top-off current threshold (MIN) through external resistors. The MAX8845Z/MAX8845Y/MAX8845X/MAX8845W feature a booting assistant circuit that distinguishes input sources and battery connection and provides an enable signal (ABO--MAX8845Z and ABO-- MAX8845Y/MAX8845X/MAX8845W) for system booting. The MAX8845Z/MAX8845Y/MAX8845X/MAX8845W also integrate an overvoltage-protected output (SAFEOUT) for low voltage-rated 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 MAX8845Z/MAX8845Y/MAX8845X/MAX8845W accept an input supply range from 4.25V (4.4V for MAX8845W only) to 28V, but disable charging if the supply voltage exceeds +7.5V (+8.0V for MAX8845X only) 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 12-pin, thermally enhanced thin QFN, 3mm x 3mm package (0.8mm max height). Applications Cellular and Cordless Phones Smart Phones and PDAs Digital Still Cameras MP3 Players USB Appliances Charging Cradles and Docks Bluetooth(R) Equipment Features o CCCV, Thermally Regulated Linear 1-Cell Li+ Battery Charger o No External MOSFET, Reverse Blocking Diode, or Current-Sense Resistor o Programmable Fast-Charge Currents (1ARMS max) o Programmable Top-Off Current Threshold (MIN) o Input Overvoltage Protected 4.7V Output (MAX8845Z/MAX8845Y/MAX8845W) or 4.85V (MAX8845X) (SAFEOUT) o Proprietary Die Temperature Regulation Control (+115C) o 4.25V (4.4V for MAX8845W only) to 28V Input Voltage Range with Input Overvoltage Protection Above +7.5V (+8.0V for MAX8845X only) o Low-Dropout Voltage (300mV at 500mA) o Input Power-Source Detection Output (POK), Charge Status Output (CHG), Charge-Enable Input (EN) o Output for Autobooting (ABO--MAX8845Z, ABO--MAX8845Y/MAX8845X/MAX8845W) o Tiny, 3mm x 3mm 12-Pin Thin QFN Package, 0.8mm Height (max) Ordering Information PART PIN-PACKAGE TOP MARK ABO ACTIVE STATE MAX8845ZETC+ 12 Thin QFN-EP* ABL Active high MAX8845YETC+ 12 Thin QFN-EP* ABM Active low MAX8845XETC+ 12 Thin QFN-EP* ABQ Active low MAX8845WETC+ 12 Thin QFN-EP* ABR Active low Note: All devices are specified over the -40C to +85C operating temperature range. +Denotes a lead(Pb)-free/RoHS-compliant package. *EP = Exposed pad. Typical Operating Circuit and Pin Configurations appear at end of data sheet. 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 MAX8845Z/MAX8845Y/MAX8845X/MAX8845W General Description MAX8845Z/MAX8845Y/MAX8845X/MAX8845W 28V Linear Li+ Battery Chargers with Battery Detection and Overvoltage Protected Output ABSOLUTE MAXIMUM RATINGS IN to GND ...............................................................-0.3V to +30V ABI, BATT, EN, POK, ABO, ABO, CHG, DETBAT, SETI, MIN, SAFEOUT to GND ................................................-0.3V to +6V IN to BATT Continuous Current .........................................1ARMS Continuous Power Dissipation (TA = +70C) 12-Thin QFN (derate 14.7mW/C above +70C) (multilayer PCB) ......................................................1176.5mW 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, VBATT = 4V, RPOK = 1M to BATT, EN = unconnected, RSETI = 2.8k to GND, VDETBAT = 0, CBATT = 2.2F, TA = -40C to +85C, unless otherwise noted. Typical values are at TA = +25C.) (Note 1) PARAMETER CONDITIONS Input Supply Voltage Range Input Supply Operating Voltage Range Overvoltage Lockout Trip Threshold Input Current MAX8845W only MIN MAX UNITS 0 TYP 28 V 4.25 7.00 4.40 7.00 VIN rising, 100mV hysteresis (typ) 7.0 7.5 8.0 MAX8845X only 7.5 8.0 8.5 Constant current charging IIN - IBATT, IBATT = 0 0.22 0.50 Constant current charging IIN - IBATT, IBATT = 500mA 1 IC disabled, VEN = 5V 0.20 VIN = 4V, VBATT = 4.2V (4.35V for MAX8845W only) TA = +25C 0.02 TA = +85C 0.03 0.50 V V mA BATT, CHG, POK Minimum BATT Bypass Capacitance VBATT Prequalification Threshold Voltage 2.2 VBATT rising, 100mV hysteresis (typ) IBATT = 0 TA = -40C to +85C Battery Regulation Voltage MAX8845W only 2.5 2.7 4.175 4.200 4.225 4.158 4.200 4.242 4.324 4.350 4.376 4.306 4.350 4.394 Regulator Dropout Voltage (VIN - VBATT) VBATT = 4.1V, IBATT = 425mA BATT Input Current VIN = 0 to 4V, VBATT = 4.2V (4.35V for MAX8845W only) 5 IC disabled 3 Current-Sense Amplifier Gain (IBATT to ISETI) Fast-Charge Current VBATT = 3.5V, RSETI = 14k CHG Top-Off Threshold 2 260 IBATT = 500mA VBATT = 3.5V, RSETI = 2.8k F 2.3 10 1016 500 540 TA = -40C to +85C 425 500 575 TA = 0C to +85C 85 100 115 _______________________________________________________________________________________ A A/A 460 106 V mV TA = 0C to +85C IBATT falling, battery is charged RMIN = 1.75k V mA mA 28V Linear Li+ Battery Chargers with Battery Detection and Overvoltage Protected Output (VIN = 5V, VBATT = 4V, RPOK = 1M to BATT, EN = unconnected, RSETI = 2.8k to GND, VDETBAT = 0, CBATT = 2.2F, TA = -40C to +85C, unless otherwise noted. Typical values are at TA = +25C.) (Note 1) PARAMETER CONDITIONS CHG Hysteresis IBATT rising after top-off is detected, RMIN = 1.75k CHG Detection Delay IBATT falls below top-off threshold Prequalification Charge Current Percentage of the fastcharge current, VBATT = 2.2V TA = 0C to +85C CHG, POK Output Low Threshold IPOK = 5mA , ICHG = 5mA CHG, POK Output High Leakage Current VPOK = 5.5V, V CHG = 5.5V POK Threshold VIN - VBATT MIN TYP 38 10.7 ms 5 10 15 % 0.4 V 1 TA = +85C 0.01 VIN rising 40 VIN falling 30 1.3 DETBAT to VL = 3V A mV 0.4 Minimum SAFEOUT Bypass Capacitance SAFEOUT Regulated Output mA 6.2 TA = +25C DETBAT Logic-Input High Threshold UNITS 4.0 DETBAT, SAFEOUT DETBAT Logic-Input Low Threshold DETBAT Pullup Resistor MAX V 470 k 1 F ISAFEOUT = 30mA, VIN = 5V, TA = 0C to +85C (MAX8845Z/MAX8845Y/MAX8845W) 4.5 4.7 4.9 ISAFEOUT = 20mA, VIN = 5V, TA = 0C to +85C (MAX8845X) 4.75 4.85 5.0 V SAFEOUT Current Limit 100 mA EN, ABI, ABO, ABO EN, ABI Internal Pulldown Resistor 100 EN Logic-Input Low Threshold 4.25V (4.4V for MAX8845W only) VIN 7V EN Logic-Input High Threshold 4.25V (4.4V for MAX8845W only) VIN 7V ABI Logic-Input Low Threshold VBATT = 4V, VIN = 0 ABI Logic-Input High Threshold VBATT = 4V, VIN = 0 ABO Output Low Threshold (MAX8845Y/ MAX8845X/MAX8845W) Open drain, IABO(SINK) = 1mA ABO Output High Threshold (MAX8845Y/ MAX8845X/MAX8845W) Open drain, 100k pullup to BATT ABO Output Low Threshold (MAX8845Z) IABO(SINK) = 1mA ABO Output High Threshold (MAX8845Z) IABO(SOURCE) = 1mA 200 400 k 0.4 V 1.3 V 0.4 1.3 V V 0.4 VBATT 0.4V V V 0.4 VBATT 0.4V V V 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. _______________________________________________________________________________________ 3 MAX8845Z/MAX8845Y/MAX8845X/MAX8845W ELECTRICAL CHARACTERISTICS (continued) Typical Operating Characteristics (VIN = 5V, VBATT = 4V, RPOK = 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.) 0.6 0.5 0.4 0.3 0.2 900 800 0.4 0.3 0.2 700 600 500 400 300 200 0.1 0.1 100 0 8 12 16 20 24 28 0 0 5 10 15 20 25 0 30 INPUT VOLTAGE (V) BATTERY VOLTAGE (V) CHARGE CURRENT vs. INPUT VOLTAGE CHARGE CURRENT vs. INPUT VOLTAGE HEADROOM SAFEOUT OUTPUT VOLTAGE vs. INPUT VOLTAGE 500 400 300 200 100 0 1000 VBATT = 4V, VIN RISING 900 800 700 600 500 400 300 8 12 16 20 24 4.0 3.5 3.0 2.5 2.0 1.5 1.0 100 0.5 28 ISAFEOUT = 1mA 4.5 200 0 0 4 5.0 SAFEOUT VOLTAGE (V) MAX8845Z/Y/X/W toc04 600 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 INPUT VOLTAGE (V) MAX8845Z/Y/X/W toc05 4 CHARGE CURRENT (mA) 0 0 100 200 300 400 500 0 600 4 8 12 16 20 24 INPUT VOLTAGE (V) VIN - VBATT (mV) INPUT VOLTAGE (V) SAFEOUT OUTPUT VOLTAGE vs. LOAD CURRENT STARTUP INTO PRECHARGE SHUTDOWN (FAST-CHARGE TO SHUTDOWN) MAX8845Z/Y/X/W toc08 MAX8845Z/Y/X/W toc07 5.0 4.5 4.0 3.5 3.0 2.5 2.0 MAX8845Z/Y/X/W toc06 0 CHARGE CURRENT (mA) MAX8845Z/Y/X/W toc03 0.5 1000 CHARGE CURRENT (mA) 0.7 VEN = 5V MAX8845Z/Y/X/W toc02 SUPPLY CURRENT (mA) 0.8 0.6 SUPPLY CURRENT (A) VEN = 0, IBATT = 0 VIN RISING 0.9 MAX8845Z/Y/X/W toc01 1.0 CHARGE CURRENT vs. BATTERY VOLTAGE DISABLED MODE SUPPLY CURRENT vs. INPUT VOLTAGE SUPPLY CURRENT vs. INPUT VOLTAGE SAFEOUT VOLTAGE (V) MAX8845Z/MAX8845Y/MAX8845X/MAX8845W 28V Linear Li+ Battery Chargers with Battery Detection and Overvoltage Protected Output MAX8845Z/Y/X/W toc09 500mA/div I 100mA/div BATT 0 IBATT 28 0 VIN 5V/div VIN 5V/div VEN 0 5V/div 0 VEN 0 5V/div 0 1.5 5V/div 5V/div 1.0 VPOK 0.5 0 0 VPOK 0 0 20 40 60 80 100 40s/div 40s/div LOAD CURRENT (mA) 4 _______________________________________________________________________________________ 28V Linear Li+ Battery Chargers with Battery Detection and Overvoltage Protected Output 0 -0.2 -0.4 -0.6 100 10 -0.8 600 TOP-OFF CURRENT THRESHOLD (mA) 0.2 MAX8845Z/Y/X/W toc11 0.4 1000 FAST-CHARGE CURRENT (mA) 0.6 MAX8845Z/Y/X/W toc10 IBATT = 0 0.8 550 500 450 400 TOP-OFF CURRENT RISING 350 300 250 200 150 TOP-OFF CURRENT FALLING 100 50 1 -1.0 -15 10 35 60 85 1 10 AMBIENT TEMPERATURE (C) 100 1000 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) 10,000 RSETI (k) AUTOBOOT ENABLED BY ABI SIGNAL (MAX8845Z) CHARGE CURRENT vs. AMBIENT TEMPERATURE MAX8845Z/Y/X/W toc14 700 MAX8845Z/Y/X/W toc13 -40 VBATT = 4V 600 CHARGE CURRENT (mA) BATTERY REGULATION ACCURACY (%) 1.0 TOP-OFF CURRENT THRESHOLD vs. 1/RMIN (k) FAST-CHARGE CURRENT vs. RSETI MAX8845Z/Y/X/W toc12 BATTERY REGULATION ACCURACY vs. AMBIENT TEMPERATURE 500 5V/div VABI 0 5V/div 400 VBATT = 3.2V VIN 0 300 5V/div 200 VBATT 0 VABO 5V/div 0 100 RSETI = 2.8k 0 -40 -20 0 20 40 60 80 100 4s/div AMBIENT TEMPERATURE (C) AUTOBOOT ENABLED BY INPUT VOLTAGE (MAX8845Z) AUTOBOOT ENABLED BY ABI SIGNAL (MAX8845Y/MAX8845X/MAX8845W) MAX8845Z/Y/X/W toc15 MAX8845Z/Y/X/W toc16 5V/div 5V/div VABI 0 VABI 0 5V/div VIN 0 5V/div VIN 0 5V/div VBATT 0 5V/div VABO 0 5V/div VBATT 0 5V/div 0 VABO 20s/div 4s/div _______________________________________________________________________________________ 5 MAX8845Z/MAX8845Y/MAX8845X/MAX8845W Typical Operating Characteristics (continued) (VIN = 5V, VBATT = 4V, RPOK = 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.) MAX8845Z/MAX8845Y/MAX8845X/MAX8845W 28V Linear Li+ Battery Chargers with Battery Detection and Overvoltage Protected Output Pin Description PIN MAX8845Z 6 MAX8845Y/ MAX8845X/ MAX8845W NAME FUNCTION Charge-Current Program and Fast-Charge Current Monitor. Output current from SETI is 1016A per ampere of battery charging current. Set the charging current by connecting a resistor (RSETI in Figure 3) from SETI to GND. IFAST-CHARGE = 1400V/RSETI. To configure the MAX8845Z/MAX8845Y/MAX8845X/MAX8845W as a USB charger, see Figure 5. 1 1 SETI 2 2 DETBAT 3 3 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. 4 4 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. 5 5 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. 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. 6 6 POK Active-Low, Input Voltage Status Indicator. POK is an open-drain output that asserts low when 2.35V < VIN < 7V (7.5V for MAX8845X only) and (VIN - VBATT) > 40mV. If VIN > +7.5V (+8.0V for MAX8845X only) or VBATT > VIN 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. 7 -- ABO Active-High, Autobooting Logic Output. See the Autobooting Assistant section and Table 1 for autobooting conditions. -- 7 ABO Active-Low, Open-Drain Logic Output. See the Autobooting Assistant section and Table 1 for autobooting conditions. 8 8 BATT Li+ Battery Connection. Bypass BATT to GND with a 2.2F ceramic capacitor. 9 9 MIN Top-Off Current Threshold Programmable Input. IMIN (mA) falling = 148V/RMIN (k) + 22 (mA). 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 CHG 11 11 IN 12 12 SAFEOUT -- -- EP Input Supply Voltage. Bypass IN to GND with a 1F or larger ceramic capacitor to improve line noise and input transient rejection. 4.7V (MAX8845Z/MAX8845Y/MAX8845W) or 4.85V (MAX8845X) Regulated LDO Output with Input Overvoltage Protection. Bypass SAFEOUT to GND with a 1F or larger ceramic capacitor. SAFEOUT can be used to supply low voltage-rated USB 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. _______________________________________________________________________________________ 28V Linear Li+ Battery Chargers with Battery Detection and Overvoltage Protected Output MAX8845Z/MAX8845Y/MAX8845X/MAX8845W LINEAR REGULATOR WITH OVP SAFEOUT 4.2V Li+ (4.35V FOR MAX8845W ONLY) BATT IN +115C OUTPUT DRIVER, CURRENT SENSE, AND LOGIC TEMPERATURE SENSOR DETBAT SETI VREF VREF VI/O IMINREF MIN IN CHG VIN OVLO VL REGULATOR POK BATT VL UVLO BATT POK VL REF ABO (MAX8845Z ONLY) LOGIC DETBAT VREF ABI REFOK ABO (MAX8845Y/MAX8845X/MAX8845W) 200k EN MAX8845Z MAX8845Y MAX8845X MAX8845W 200k GND EP Figure 1. MAX8845Z/MAX8845Y/MAX8845X/MAX8845W Functional Diagram Detailed Description The MAX8845Z/MAX8845Y/MAX8845X/MAX8845W 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 MAX8845Z/MAX8845Y/MAX8845X/ MAX8845W chargers enter a prequalification stage where it precharges that cell with 10% of the user-pro- grammed 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 charging current is reduced. If the battery current drops to less than the _______________________________________________________________________________________ 7 MAX8845Z/MAX8845Y/MAX8845X/MAX8845W 28V Linear Li+ Battery Chargers with Battery Detection and Overvoltage Protected Output VBATT < 2.5V SHUTDOWN CHARGER = DISABLED CHG = HIGH-Z (VIN - VBATT) < 30mV PRECHARGE 10% OF IFAST-CHARGE CHG = LOW VIN < OVP, AND (VIN - VBATT) 40mV, AND IC ENABLED ANY CHARGING STATE VBATT < 2.4V VIN > OVP, OR (VIN - VBATT) < 30mV, OR IC DISABLED DIE TEMPERATURE > +115C ASYNCHRONOUS FROM ANYWHERE VIN > OVP, OR (VIN - VBATT) < 30mV, OR THERMAL SHUTDOWN, OR IC DISABLED CHARGING CURRENT REDUCTION CHARGING CURRENT IS REDUCED AS NECESSARY VBATT 2.5V FAST-CHARGE CONSTANT-CURRENT CHARGE 100% OF IFAST-CHARGE CHG = LOW IBATT > 295V/RMIN (k) - 24mA IBATT IMIN FOR 6.2ms (typ) OR LONGER TOP-OFF 4.2 VOLTAGE REGULATION CHG = HIGH-Z (MAX8845Z/MAX8845Y/MAX8845X) 4.35 VOLTAGE REGULATION (MAX8845W) DIE TEMPERATURE +115C RETURN TO CHARGING STATE Figure 2. Charge-State Diagram 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 (SAFEOUT) SAFEOUT is a linear regulator that provides an output voltage of 4.7V (MAX8845Z/MAX8845Y/MAX8845W) or 4.85V (MAX8845X) and can be used to supply low voltage- rated USB systems. The SAFEOUT linear regulator turns on when VIN 4.25V regardless of EN and is disabled when VIN is greater than the overvoltage threshold (7.5V typ) (8.0V typ for MAX8845X only). 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. If DETBAT is not used connect DETBAT to GND for normal operation. POK Output The open-drain POK output asserts low when 2.35V VIN 7V (7.5V for MAX8845X only) and (VIN - VBATT) 40mV (typ VIN rising). POK is high impedance during shutdown. When interfacing with a microprocessor logic input, a pullup resistor to the microprocessor's I/O voltage may be required. 8 Autobooting Assistant The MAX8845Z/MAX8845Y/MAX8845X/MAX8845W contain autobooting assistant circuits that generate an enable signal for system booting (ABO--MAX8845Z, ABO--MAX8845Y/MAX8845X/MAX8845W). For the MAX8845Z, the booting assistant functions as an internal OR gate (Figure 1). The first input is dependant on the input voltage (VIN) 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 7V (7.5V for only MAX8845X), and (VIN - 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, a RC filter (Figure 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 MAX8845Y/MAX8845X/ MAX8845W, the output ABO is only dependent on the state of ABI (Table 1). 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 MAX8845Z/MAX8845Y/MAX8845X/ _______________________________________________________________________________________ 28V Linear Li+ Battery Chargers with Battery Detection and Overvoltage Protected Output ABI BATT POK CHARGER STATE ABO (MAX8845Z) ABO (MAX8845Y/ MAX8845X/MAX8845W) 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 2V and Not Present indicates that the battery is not connected. Table 2. CHG States EN High VIN VBATT IBATT CHG STATE 0 High-Z Disabled 0 High-Z Shutdown X X > 7.5V X X > VIN - 30mV Low 4.25V (4.4V for MAX8845W only) VIN 7.5V < 2.4V 10% of IFAST-CHARGE* Low Precharge Low 4.25V (4.4V for MAX8845W only) VIN 7.5V 2.5V 100% of IFAST-CHARGE* Low Fast-charge Low 4.25V (4.4V for MAX8845W only) VIN 7.5V 4.2V (4.35V for MAX8845W only) < IMIN High-Z Top-off Low X = Don't care. *IFAST-CHARGE is reduced as necessary to prevent the die temperature from exceeding +115C. MAX8845W 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 MAX8845Z/ MAX8845Y/MAX8845X/MAX8845W die temperature 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. Charger Enable Input The MAX8845Z/MAX8845Y/MAX8845X/MAX8845W contain 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. 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 = 1400V RSETI where IFAST_CHARGE is in amps and RSETI is in ohms. RSETI must always be 1.4k or higher due to the continuous charging current limit of 1ARMS. 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) = 148V/RMIN (k) + 22mA IMIN (rising) = 295V/RMIN (k) - 24mA where IMIN is in mA and RMIN is in k. Use RMIN 2.2k. _______________________________________________________________________________________ 9 MAX8845Z/MAX8845Y/MAX8845X/MAX8845W Table 1. Autobooting Output States MAX8845Z/MAX8845Y/MAX8845X/MAX8845W 28V Linear Li+ Battery Chargers with Battery Detection and Overvoltage Protected Output Capacitor Selection Connect a ceramic capacitor from BATT to GND for proper stability. Use a 2.2F ceramic capacitor for most applications. Connect a 1F ceramic capacitor from IN to GND. A larger input capacitor can be used for high charging current to reduce input voltage ripple. Connect a 1F ceramic capacitor from SAFEOUT to GND. A larger bypass capacitor for SAFEOUT 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 MAX8845Z/MAX8845Y/MAX8845X/MAX8845W are available in thermally enhanced Thin QFN packages with exposed pads. 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. DC Input Sources The MAX8845Z/MAX8845Y/MAX8845X/MAX8845W operate from well-regulated DC sources. The full charging input voltage range is 4.25V (4.4V for MAX8845W only) to 7.5V (8V for MAX8845X only). The device can withstand up to 28V on the input without damage to the IC. If VIN is greater than 7.5V (8V for MAX8845X only), the internal overvoltage-protection circuitry disables charging until the input falls below 7.5V (8V for MAX8845X only). An appropriate power supply must provide at least 4.25V at the desired peak charging current and stay below 7V when unloaded. Typical Application Circuits AC Adapter Application Figure 3 shows the MAX8845Z as a Li+ battery charger with an AC adapter. The MAX8845Z 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 (MAX8845Z) and enables the power 10 supplies of the system to boot up. The MAX8845Z 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 MAX8845Z/MAX8845Y/MAX8845X/MAX8845W also provide an overvoltage-protected SAFEOUT to the system. Factory System Interface Connector Application Figure 4 shows the MAX8845Z as an autoboot assistor with the factory system interface connector. The MAX8845Z detects the ABI input even though there is no input voltage available and generates an ABO signal to turn 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-Ion Charger The universal serial bus (USB) provides a high-speed serial communication port as well as power for the remote device. The MAX8845Z/MAX8845Y/MAX8845X/ MAX8845W can be configured to charge batteries at the highest current possible from the host port. Figure 5 shows the MAX8845Z as a USB battery charger. To make the circuit compatible with either 100mA or 500mA USB ports, the circuit initializes at 100mA charging current. The microprocessor then enumerates the host to determine its current capability. If the host port is capable, the charging current is increased to 450mA to avoid exceeding the 500mA USB specification through GPIO control. The MAX8845Z/MAX8845Y/MAX8845X/ MAX8845W also provide an overvoltage-protected SAFEOUT to the system. Recommended PCB Layout and Routing Place all bypass capacitors for IN, BATT, and SAFEOUT as close as possible to the device. 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 MAX8845Z Evaluation Kit to speed designs. ______________________________________________________________________________________ 28V Linear Li+ Battery Chargers with Battery Detection and Overvoltage Protected Output AC ADAPTER MAX8845Z/MAX8845Y/MAX8845X/MAX8845W 4.2V Li+ IN BATT CIN 1F SYSTEM CBATT 2.2F GND MAX8845Z DETBAT ABI SAFEOUT VBUS 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 ON Figure 3. AC Adapter Application ______________________________________________________________________________________ 11 MAX8845Z/MAX8845Y/MAX8845X/MAX8845W 28V Linear Li+ Battery Chargers with Battery Detection and Overvoltage Protected Output IN BATT CIN 1F 4.2V INTERFACE CONNECTOR GND SYSTEM CBATT 2.2F MAX8845Z RABI 10k DETBAT ABI CABI 1F SAFEOUT VBUS 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 ON Figure 4. Factory System Interface Connector Application 12 ______________________________________________________________________________________ IF THE POWER SUPPLY IS ACTIVE-LOW ENABLED, USE THE MAX8845Y. 28V Linear Li+ Battery Chargers with Battery Detection and Overvoltage Protected Output MINI-USB CONNECTOR GND MAX8845Z/MAX8845Y/MAX8845X/MAX8845W 4.2V Li+ IN BATT CIN 1F SYSTEM CBATT 2.2F MAX8845Z DETBAT SAFEOUT ABI VBUS CSAFEOUT 1F VI/O RCHG 1M RPOK 1M SETI RSETIA 15.4k RSETI 3.42k MIN GPIO CHG ABO GND EP POK GPIO EN GPIO RMIN 3.09k GPIO POWER SUPPLY ON Figure 5. Mini USB Battery Charger ______________________________________________________________________________________ 13 MAX8845Z/MAX8845Y/MAX8845X/MAX8845W 28V Linear Li+ Battery Chargers with Battery Detection and Overvoltage Protected Output OVP OVP POK VIN VPOK VEN VCHG VSAFEOUT = 4.7V (4.85V FOR MAX8845X ONLY) VSAFEOUT TIME Figure 6. Timing Diagram 14 ______________________________________________________________________________________ 28V Linear Li+ Battery Chargers with Battery Detection and Overvoltage Protected Output 4.25V (4.4V FOR MAX8845W ONLY) TO 28V DETBAT IN BATT CIN 1F CBATT 2.2F MAX8845Z MAX8845Y MAX8845X MAX8845W ABI OFF ON 4.2V (4.35V FOR MAX8845W ONLY) Li+ SYSTEM SUPPLY EN MIN RMIN 1.75k CHG SETI RSET 2.80k POK (MAX8845Z, ABO) (MAX8845Y/MAX8845X/MAX8845W, ABO) SAFEOUT GND EP VSAFEOUT 1F ______________________________________________________________________________________ 15 MAX8845Z/MAX8845Y/MAX8845X/MAX8845W Typical Operating Circuit 28V Linear Li+ Battery Chargers with Battery Detection and Overvoltage Protected Output TOP VIEW MIN BATT ABO MIN BATT ABO TOP VIEW 9 8 7 9 8 7 *EXPOSED PAD + 1 2 3 POK 5 GND 4 EN CHG 10 IN 11 SAFEOUT 12 MAX8845Y MAX8845X MAX8845W *EXPOSED PAD + 1 2 6 POK 5 GND 4 EN 3 ABI 12 ABI SAFEOUT MAX8845Z DETBAT 11 SETI IN 6 DETBAT CHG 10 SETI MAX8845Z/MAX8845Y/MAX8845X/MAX8845W Pin Configurations Chip Information PROCESS: BiCMOS 16 ______________________________________________________________________________________ 28V Linear Li+ Battery Chargers with Battery Detection and Overvoltage Protected Output PACKAGE CODE DOCUMENT NO. 12 Thin QFN-EP (3mm x 3mm) T1233-4 -- (NE - 1) X e E MARKING THIN QFN.EPS PACKAGE TYPE E/2 D2/2 (ND - 1) X e D/2 AAAA e C L D D2 b k C L 0.10 M C A B E2/2 L E2 0.10 C C L C L 0.08 C A A2 A1 L L e e PACKAGE OUTLINE, 12L THIN QFN, 3X3X0.75mm 21-0136 custom eng 1 2 ______________________________________________________________________________________ 17 MAX8845Z/MAX8845Y/MAX8845X/MAX8845W Package Information For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. MAX8845Z/MAX8845Y/MAX8845X/MAX8845W 28V Linear Li+ Battery Chargers with Battery Detection and Overvoltage Protected Output Package Information (continued) For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. PKG 12L 3x3 EXPOSED PAD VARIATIONS REF. MIN. NOM. MAX. 0.75 0.80 A 0.70 b 0.20 0.25 0.30 D 2.90 E e 2.90 3.00 3.10 0.50 BSC. L 0.45 3.00 0.55 N 12 ND 3 NE k E2 D2 MIN. NOM. MAX. MIN. NOM. MAX. PIN ID JEDEC T1233-1 0.95 1.10 1.25 0.95 1.10 1.25 0.35 x 45 WEED-1 T1233-3 0.95 1.10 1.25 0.95 1.10 1.25 0.35 x 45 WEED-1 T1233-4 0.95 1.10 1.25 0.95 1.10 1.25 0.35 x 45 WEED-1 0.65 3 A1 A2 3.10 PKG. CODES 0 0.02 0.05 0.20 REF 0.25 NOTES: 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. DIMENSIONING & TOLERANCING CONFORM TO ASME Y14.5M-1994. ALL DIMENSIONS ARE IN MILLIMETERS. ANGLES ARE IN DEGREES. N IS THE TOTAL NUMBER OF TERMINALS. THE TERMINAL #1 IDENTIFIER AND TERMINAL NUMBERING CONVENTION SHALL CONFORM TO JESD 95-1 SPP-012. DETAILS OF TERMINAL #1 IDENTIFIER ARE OPTIONAL, BUT MUST BE LOCATED WITHIN THE ZONE INDICATED. THE TERMINAL #1 IDENTIFIER MAY BE EITHER A MOLD OR MARKED FEATURE. DIMENSION b APPLIES TO METALLIZED TERMINAL AND IS MEASURED BETWEEN 0.20 mm AND 0.25 mm FROM TERMINAL TIP. ND AND NE REFER TO THE NUMBER OF TERMINALS ON EACH D AND E SIDE RESPECTIVELY. DEPOPULATION IS POSSIBLE IN A SYMMETRICAL FASHION. COPLANARITY APPLIES TO THE EXPOSED HEAT SINK SLUG AS WELL AS THE TERMINALS. DRAWING CONFORMS TO JEDEC MO220 REVISION C. MARKING IS FOR PACKAGE ORIENTATION REFERENCE ONLY. NUMBER OF LEADS SHOWN ARE FOR REFERENCE ONLY. WARPAGE NOT TO EXCEED 0.10mm. PACKAGE OUTLINE, 12L THIN QFN, 3X3X0.75mm 21-0136 custom eng 18 ______________________________________________________________________________________ 2 2 28V Linear Li+ Battery Chargers with Battery Detection and Overvoltage Protected Output REVISION NUMBER REVISION DATE 0 3/09 Initial release 1 9/09 Corrected the POK Output section description and added MAX8845X and MAX8845W to data sheet DESCRIPTION PAGES CHANGED -- 1-19 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 ____________________ 19 (c) 2009 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc. MAX8845Z/MAX8845Y/MAX8845X/MAX8845W Revision History