MAXIM INTEGRATED PRODUCTS Stand-Alone, Switch-Mode Li+ Battery Charger with Internal 28V Switch Owner's Manual

19-1752; Rev 1; 1/01

EVALUATION KIT AVAILABLE

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-

tery. The built-in safety timer automatically terminates Continuous Voltage and Temperature Monitoring

charging once the adjustable time limit has been

0.1µA Shutdown Battery Current

reached.

Input Voltage Up to 28V

The MAX1758 regulates the voltage set point and

charging current using two loops that work together to Up to 1.5A Programmable Charge Current

transition smoothly between voltage and current regula-

Safety Timer Prevents Overcharging

tion. An additional control loop monitors the total cur-

rent drawn from the input source (charging + system), Input Current Limiting

and automatically reduces battery-charging current,

Space-Saving 28-Pin SSOP

preventing overload of the input supply and allowing

300k Hz PWM Oscillator Reduces Noise

the use of a low-cost wall adapter. The per-cell battery regulation voltage is set between

4.0V and 4.4V using standard 1% resistors. The num- Ordering Information

ber of cells is set from 1-to-4 by pin strapping. Battery

temperature is monitored by an external thermistor to PART PIN-PACKAGETEMP. RANGE

prevent charging outside the acceptable temperature -40°C to +85°CMAX1758EAI 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

switch, refer to the MAX1757 data sheet. For a charger VIN 6V TO 28V

controller capable of up to 4A charging current, refer to

DCIN CSSP

the MAX1737 data sheet. SYSTEM

________________________Applications HSD LX

Li+ Battery Packs Hand-Held Instruments MAX1758

Notebook Computers Desktop Cradle Chargers ISETOUT BST

Pin Configuration

ISETIN

TOP VIEW

CELL CS

VL DCIN

ISETIN CSSP

ISETOUT CSSN

THM CCV THM

REF CCI

CCS Li+ BATTERY

MAX1758 THERM 1 TO 4 CELLS

GND CCS

VADJ BST

BATT CS

HSD LX

CCV FASTCHG

HSD LX

CELL PGND TIMER1 FULLCHG

TIMER1 SHDN

TIMER2 FAULT

TIMER2 FULLCHG

FAULT FASTCHG OFF SHDN

Maxim Integrated Products

For price, delivery, and to place orders, please contact Maxim Distribution at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.