19-1752; Rev 1; 1/01
Stand-Alone, Switch-Mode
Li+ Battery Charger with Internal 28V Switch
General Description
Features
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 1ꢀ0 and a regu-
lated voltage with only a ꢀ.80 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.
ꢀ Stand-Alone Charger for Up to 4 Li+ Batteries
ꢀ ±±0.8 Batterꢀ ꢁegꢂlation ꢃoltage Aꢄꢄꢂraꢄꢀ
ꢀ Low-Dropoꢂt 9.8 Dꢂtꢀ Cꢀꢄle
ꢀ Safelꢀ Preꢄharges Near-Dead Cells
ꢀ Continꢂoꢂs ꢃoltage and Temperatꢂre Monitoring
ꢀ ±01µA Shꢂtdown Batterꢀ Cꢂrrent
ꢀ Inpꢂt ꢃoltage Up to 2.ꢃ
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.
ꢀ Up to 105A Programmable Charge Cꢂrrent
ꢀ Safetꢀ Timer Prevents Overꢄharging
ꢀ Inpꢂt Cꢂrrent Limiting
ꢀ Spaꢄe-Saving 2.-Pin SSOP
ꢀ 3±±kHz PWM Osꢄillator ꢁedꢂꢄes Noise
The per-cell battery regulation voltage is set between
4.ꢀV and 4.4V using standard 10 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.
Ordering Information
PAꢁT
TEMP0 ꢁANGE
PIN-PACKAGE
MAX1758EAI
-4ꢀ°C to +85°C
28 SSOP
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.
Typical Operating Circuit
V
IN
6V TO 28V
DCIN
CSSP
CSSN
SYSTEM
LOAD
REF
HSD
LX
________________________Applications
Li+ Battery Packs
Hand-Held Instruments
MAX1758
ISETOUT
BST
VL
Notebook Computers
Desktop Cradle Chargers
Pin Configuration
ISETIN
CELL
PGND
CS
TOP VIEW
VL
ISETIN
ISETOUT
THM
1
2
3
4
5
6
7
8
9
28 DCIN
27 CSSP
26 CSSN
25 CCV
24 CCI
VADJ
BATT
THM
REF
CCS
CCI
Li+ BATTERY
1 TO 4 CELLS
MAX1758
THERM
GND
23 CCS
VADJ
BATT
22 BST
21 CS
HSD
20 LX
CCV
FASTCHG
FULLCHG
FAULT
HSD 10
CELL 11
19 LX
TIMER1
TIMER2
SHDN
18 PGND
17 SHDN
16 FULLCHG
15 FASTCHG
TIMER1 12
TIMER2 13
FAULT 14
ON
OFF
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.