19-1752; Rev 1; 1/01
Stand-Alone, Switch-Mode
Li+ Battery Charger with Internal 28V Switch
General Description
The MAX1758 is a switch-mode lithium-ion (Li+) battery
charger that charges one-to-four cells. It provides a reg-
ulated charging current accurate to ±10% and a regu-
lated voltage with only a ±0.8% total voltage error at the
battery terminals. The internal high-side switch delivers
a programmable current of up to 1.5A to charge the bat-
tery. The built-in safety timer automatically terminates
charging once the adjustable time limit has been
reached.
The MAX1758 regulates the voltage set point and
charging current using two loops that work together to
transition smoothly between voltage and current regula-
tion. An additional control loop monitors the total cur-
rent drawn from the input source (charging + system),
and automatically reduces battery-charging current,
preventing overload of the input supply and allowing
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-
ber of cells is set from 1-to-4 by pin strapping. Battery
temperature is monitored by an external thermistor to
prevent charging outside the acceptable temperature
range.
The MAX1758 is available in a space-saving 28-pin
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
controller capable of up to 4A charging current, refer to
the MAX1737 data sheet.
KIT
ATION
EVALU
BLE
AVAILA
Features
o
Stand-Alone Charger for Up to 4 Li+ Batteries
o
±0.8% Battery Regulation Voltage Accuracy
o
Low-Dropout 98% Duty Cycle
o
Safely Precharges Near-Dead Cells
o
Continuous Voltage and Temperature Monitoring
o
0.1µA Shutdown Battery Current
o
Input Voltage Up to 28V
o
Up to 1.5A Programmable Charge Current
o
Safety Timer Prevents Overcharging
o
Input Current Limiting
o
Space-Saving 28-Pin SSOP
o
300kHz PWM Oscillator Reduces Noise
MAX1758
Ordering Information
PART
MAX1758EAI
TEMP. RANGE
-40°C to +85°C
PIN-PACKAGE
28 SSOP
Typical Operating Circuit
V
IN
6V TO 28V
DCIN
REF
CSSP
CSSN
HSD
LX
MAX1758
ISETOUT
BST
VL
ISETIN
SYSTEM
LOAD
________________________Applications
Li+ Battery Packs
Notebook Computers
Hand-Held Instruments
Desktop Cradle Chargers
Pin Configuration
TOP VIEW
CELL
PGND
CS
VL 1
ISETIN 2
ISETOUT 3
THM 4
REF 5
GND 6
VADJ 7
BATT 8
HSD 9
HSD 10
CELL 11
TIMER1 12
TIMER2 13
FAULT 14
28 DCIN
27 CSSP
26 CSSN
25 CCV
24 CCI
VADJ
BATT
THM
CCS
THERM
CCI
Li+ BATTERY
1 TO 4 CELLS
MAX1758
23 CCS
22 BST
21 CS
20 LX
CCV
FASTCHG
19 LX
18 PGND
17 SHDN
TIMER2
FAULT
TIMER1
FULLCHG
16 FULLCHG
15 FASTCHG
ON
OFF
SHDN
GND
SSOP
________________________________________________________________
Maxim Integrated Products
1
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.
MAXIM [ MAXIM INTEGRATED PRODUCTS ]
