MAX1879 19-2061 Rev 0 5/01 Simple, Efficient, 1-Cell Li+ Pulse Charger General Description Features The MAX1879 single-cell lithium-ion (Li+) battery charger Simple Design Minimizes Heat utilizes an efficient pulse-charging architecture to minimize Low Component Count, No Inductor power dissipation in portable devices. This architecture combines the efficiency of switch-mode chargers with the Battery-Full Indicator simplicity and low cost of linear chargers. This simple 0.75% Accurate Battery Regulation device, in conjunction with a current-limited wall cube and a PMOS transistor, allows safe and fast charging of a sin- 1.5A (max) Battery Current Drain with Wall Cube gle Li+ cell. Removed The MAX1879 initiates charging in one of three ways: bat- Restart Charging at 4.0V tery insertion, charger power-up, or toggling the THERM Continuous Overvoltage and Overtemperature pin. Key safety features include continuous voltage and Protection temperature monitoring, a preset charger time-out, and an 8mA precharge current mode to charge near-dead cells. Safely Precharges Near-Dead Cells Automatic detection of input power removal shuts down Automatic Power-Down when Power Source is the device, minimizing current drain from the battery. An Removed overall system accuracy of 0.75% ensures that the cell capacity is fully utilized without cycle life degradation. Charges 1 Cell from as Low as 4.5V Pin-Compatible Upgrade to MAX1679 The MAX1879 is offered in a space-saving 8-pin MAX package. An evaluation kit (MAX1879EVKIT) is available to help reduce design time. Applications Ordering Information Single-Cell Li+ Powered Portables PART TEMP. RANGE PIN-PACKAGE Self-Charging Battery Packs MAX1879EUA -40C to +85C 8-MAX PDAs Cell Phones Cradle Chargers Pin Configuration Typical Operating Circuit TOP VIEW CURRENT- LIMITED AC WALL ADAPTER IN 1 8 BATT LED GATE 2 7 THERM IN GATE MAX1879 CHG 3 6 GND CHG BATT 1-CELL Li+ TSEL 4 5 ADJ BATTERY MAX1879 PULSE WIDTH TSEL GND SELECT INPUT MAX THERM ADJ THERMISTOR Maxim Integrated Products 1 For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct at 1-888-629-4642, or visit Maxims website at www.maxim-ic.com. EVALUATION KIT AVAILABLESimple, Efficient, 1-Cell Li+ Pulse Charger ABSOLUTE MAXIMUM RATINGS IN, CHG, GATE to GND..........................................-0.3V to +26V Continuous Power Dissipation (T = +70C) A BATT, TSEL, THERM, ADJ to GND...........................-0.3V to +6V 8-Pin MAX (derate 4.1mW/C above +70C) ............ 330mW GATE to IN................................................................-6V to +0.3V Operating Temperature Range ...........................-40C to +85C THERM, ADJ to BATT...............................................-6V to +0.3V Storage Temperature Range ............................ -65C to +150C GATE Continuous Current ................................................ -10mA 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 (V = V = +10V, V = +4.2V, TSEL = GND, GATE = unconnected, ADJ = unconnected, THERM = 10k to GND, T = 0C to IN CHG BATT A +85C, unless otherwise noted. Typical values are at T = +25C.) A PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Input Voltage (Note 1) V External PMOS FET off 4.4 22 V IN Undervoltage Lockout Trip Point BATT rising 2.1 2.2 2.3 V Undervoltage Lockout Trip-Point BATT falling 60 mV Hysteresis Fast-Charge Qualification BATT rising, transition from precharge to 2.425 2.5 2.575 V Threshold full current BATT falling, transition from Done to Fast-Charge Restart Threshold 3.92 4.00 4.08 V Prequalification state (Note 2) Fast-Charge Reset Threshold (Note 3) 1 ms Delay Precharge Source Current V = 2V 5 8 12 mA BATT BATT Regulation Voltage 4.1685 4.2000 4.2315 V BATT Regulation Adjust Range 4.0 4.2 V ADJ Source Impedance 9.8 10 10.2 k ADJ Output Voltage No load on ADJ 1.393 1.400 1.407 V BATT Removal Detection BATT rising 4.875 5 5.125 V Threshold BATT Removal Detection BATT falling 125 mV Threshold Hysteresis BATT Input Current (Note 4) V V - 0.3V 0.1 1.5 A IN BATT BATT Input Current, Fast-Charge I V = 4.0V 900 1500 A BATT BATT State BATT Input Current, Done State I V = 4.25V, V present 85 200 A BATT BATT IN IN Input Current, Fast-Charge I V = 4.0V, V = 4.0V 50 500 A IN BATT IN State IN Input Current, Done State I V = 4.25V, V = 22V 700 1200 A IN BATT IN Timer Accuracy -10 +10 % CHG Output Leakage Current V = 22V, CHG = high -1 +1 A CHG CHG Output Sink Current V = 1.0V, CHG = low 4 5 6 mA CHG 2 MAX1879