19-2061; Rev 0; 5/01
AILABLE
ION KIT AV
EVALUAT
Simple, Efficient, 1-Cell Li+ Pulse Charger
General Description
The MAX1879 single-cell lithium-ion (Li+) battery charger
utilizes an efficient pulse-charging architecture to minimize
power dissipation in portable devices. This architecture
combines the efficiency of switch-mode chargers with the
simplicity and low cost of linear chargers. This simple
device, in conjunction with a current-limited wall cube and
a PMOS transistor, allows safe and fast charging of a sin-
gle Li+ cell.
The MAX1879 initiates charging in one of three ways: bat-
tery insertion, charger power-up, or toggling the THERM
pin. Key safety features include continuous voltage and
temperature monitoring, a preset charger time-out, and an
8mA precharge current mode to charge near-dead cells.
Automatic detection of input power removal shuts down
the device, minimizing current drain from the battery. An
overall system accuracy of 0.75% ensures that the cell
capacity is fully utilized without cycle life degradation.
The MAX1879 is offered in a space-saving 8-pin µMAX
package. An evaluation kit (MAX1879EVKIT) is available
to help reduce design time.
o
Simple Design Minimizes Heat
o
Low Component Count, No Inductor
o
Battery-Full Indicator
o
0.75% Accurate Battery Regulation
o
1.5µA (max) Battery Current Drain with Wall Cube
Removed
o
Restart Charging at 4.0V
o
Continuous Overvoltage and Overtemperature
Protection
o
Safely Precharges Near-Dead Cells
o
Automatic Power-Down when Power Source is
Removed
o
Charges 1 Cell from as Low as 4.5V
o
Pin-Compatible Upgrade to MAX1679
Features
MAX1879
Applications
Single-Cell Li+ Powered Portables
Self-Charging Battery Packs
PDAs
Cell Phones
Cradle Chargers
PART
MAX1879EUA
Ordering Information
TEMP. RANGE
-40°C to +85°C
PIN-PACKAGE
8-µMAX
Pin Configuration
TOP VIEW
CURRENT-
LIMITED
AC WALL
ADAPTER
LED
Typical Operating Circuit
IN
GATE
CHG
1
2
8
7
BATT
THERM
GND
ADJ
MAX1879
3
6
5
TSEL
4
IN
CHG
GATE
BATT
1-CELL
Li+
BATTERY
MAX1879
PULSE WIDTH
SELECT INPUT
TSEL
THERM
THERMISTOR
GND
ADJ
µMAX
________________________________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
MAXIM [ MAXIM INTEGRATED PRODUCTS ]
