EVALUATION KIT AVAILABLE MAX1758 Stand-Alone, Switch-Mode Li+ Battery Charger with Internal 28V Switch General Description Features The MAX1758 is a switch-mode lithium-ion (Li+) battery Stand-Alone Charger for Up to 4 Li+ Batteries charger that charges one-to-four cells. It provides a reg- 0.8% Battery Regulation Voltage Accuracy ulated charging current accurate to 10% and a regu- lated voltage with only a 0.8% total voltage error at the Low-Dropout 98% Duty Cycle battery terminals. The internal high-side switch delivers Safely Precharges Near-Dead Cells a programmable current of up to 1.5A to charge the bat- Continuous Voltage and Temperature Monitoring tery. The built-in safety timer automatically terminates charging once the adjustable time limit has been 0.1A Shutdown Battery Current reached. Input Voltage Up to 28V The MAX1758 regulates the voltage set point and Up to 1.5A Programmable Charge Current charging current using two loops that work together to transition smoothly between voltage and current regula- Safety Timer Prevents Overcharging tion. An additional control loop monitors the total cur- Input Current Limiting rent drawn from the input source (charging + system), and automatically reduces battery-charging current, Space-Saving 28-Pin SSOP preventing overload of the input supply and allowing 300kHz PWM Oscillator Reduces Noise the use of a low-cost wall adapter. The per-cell battery regulation voltage is set between Ordering Information 4.0V and 4.4V using standard 1% resistors. The num- ber of cells is set from 1-to-4 by pin strapping. Battery PART TEMP. RANGE PIN-PACKAGE temperature is monitored by an external thermistor to prevent charging outside the acceptable temperature MAX1758EAI -40C to +85C 28 SSOP range. The MAX1758 is available in a space-saving 28-pin Typical Operating Circuit SSOP package. Use the MAX1758EVKIT to help reduce design time. For a stand-alone charger with a 14V V switch, refer to the MAX1757 data sheet. For a charger IN 6V TO 28V controller capable of up to 4A charging current, refer to DCIN CSSP SYSTEM the MAX1737 data sheet. CSSN LOAD REF HSD Applications MAX1758 LX Li+ Battery Packs Hand-Held Instruments ISETOUT BST Notebook Computers Desktop Cradle Chargers VL Pin Configuration ISETIN PGND TOP VIEW CELL CS VL 1 28 DCIN VADJ ISETIN 2 27 CSSP BATT ISETOUT 3 26 CSSN THM THM 4 25 CCV REF 5 24 CCI CCS Li+ BATTERY MAX1758 THERM 1 TO 4 CELLS GND 6 23 CCS CCI VADJ 7 22 BST BATT 8 21 CS HSD 9 20 LX CCV FASTCHG HSD 10 19 LX TIMER1 FULLCHG CELL 11 18 PGND TIMER1 12 17 SHDN TIMER2 FAULT TIMER2 13 16 FULLCHG ON OFF SHDN FAULT 14 15 FASTCHG GND SSOP For pricing, delivery, and ordering information, please contact Maxim Direct 19-1752 Rev 1 1/01 at 1-888-629-4642, or visit Maxims website at www.maximintegrated.com.MAX1758 Stand-Alone, Switch-Mode Li+ Battery Charger with Internal 28V Switch ABSOLUTE MAXIMUM RATINGS DCIN, CSSP, CSSN, HSD to GND..........................-0.3V to +30V CS to BATT Current ............................................................3.5A CSSP to CSSN.......................................................-0.6V to +0.6V PGND to GND .......................................................-0.3V to +0.3V BST to GND............................................................-0.3V to +36V VL Source Current...............................................................50mA BST to LX..................................................................-0.3V to +6V Continuous Power Dissipation (T = +70C) A LX to PGND ..............................................-0.6V to (V + 0.3V) 28-Pin SSOP (derate 9.5mW/C above +70C) ...........762mW HSD VL, SHDN, ISETIN, ISETOUT, REF, VADJ, CELL, TIMER1, Operating Temperature Range ...........................-40C to +85C TIMER2, CCI, CCS, CCV, THM to GND ................-0.3V to +6V Junction Temperature......................................................+150C FASTCHG, FULLCHG, FAULT to GND ..................-0.3V to +30V Storage Temperature.........................................-65C to +150C BATT, CS to GND...................................................-0.3V to +20V 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 (Circuit of Figure 1, V = V = V = V = 18V, V = V , V = GND, V = V = 4.2V, V = V / 2, DCIN HSD CSSP CSSN SHDN VL CELL BATT CS VADJ REF V = V = V , R = 10k, T = 0C to +85C, unless otherwise noted. Typical values are at T = +25C.) ISETIN ISETOUT REF THM A A PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS SUPPLY AND REFERENCE DCIN Input Voltage Range 628 V DCIN Quiescent Supply Current 6V < V < 28V 57 mA DCIN DCIN to BATT Dropout Falling edge 0.075 0.125 0.175 V Threshold, DCIN Falling DCIN to BATT Dropout Rising edge 0.20 0.30 0.40 V Threshold, DCIN Rising VL Output Voltage 6V < V < 28V 5.10 5.40 5.70 V DCIN VL Output Load Regulation I = 0 to 15mA 44 65 mV VL REF Output Voltage V 6V < V < 28V 4.179 4.20 4.221 V REF DCIN REF Line Regulation 6V < V < 28V 26 mV DCIN REF Load Regulation I = 0 to 1mA 614 mV REF SWITCHING REGULATOR PWM Oscillator Frequency f Nondropout f 270 300 330 kHz OSC OSC LX Maximum Duty Cycle In-dropout, f / 4 97 98 % OSC CSSN/CSSP Off-State Leakage V = V = V = 28V, V = GND 210 A CSSN CSSP DCIN SHDN V = PGND, V = V = 28V, LX HSD DCIN HSD Off-State Leakage 0.1 10 A V = GND SHDN LX Off-State Leakage V = V = V =28V, V = GND 0.1 10 A LX HSD DCIN SHDN HSD to LX On-Resistance V = V + 4.5V 260 450 m BST LX LX to PGND On-Resistance See PWM Controller section 12 CS to BATT Current-Sensing Internal resistor between CS and BATT, R 110 170 m CS Resistance 1.5A RMS operating V = GND, V = 19V 0.1 5 A SHDN BATT BATT, CS Input Current CELL = REF, V = 15V, any charging state 280 540 A BATT V = 18V, done state 150 270 A BATT 2 Maxim Integrated