19-1626; Rev 4; 9/07
KIT
ATION
EVALU
BLE
AVAILA
Stand-Alone Switch-Mode
Lithium-Ion Battery-Charger Controller
General Description
Features
♦
Stand-Alone Charger for Up to Four Li+ Cells
♦
±0.8% Accurate Battery Regulation Voltage
♦
Low Dropout: 98% Duty Cycle
♦
Safely Precharges Near-Dead Cells
♦
Continuous Voltage and Temperature Monitoring
♦
<1µA Shutdown Battery Current
♦
Input Voltage Up to +28V
♦
Safety Timer Prevents Overcharging
♦
Input Current Limiting
♦
Space-Saving 28-Pin QSOP
♦
300kHz PWM Oscillator Reduces Noise
♦
90% Conversion Efficiency
MAX1737
The MAX1737 is a switch-mode lithium-ion (Li+) battery
charger that charges one to four cells. It provides a
regulated charging current and a regulated voltage
with only a ±0.8% total voltage error at the battery ter-
minals. The external N-channel switch and synchronous
rectifier provide high efficiency over a wide input volt-
age range. A built-in safety timer automatically termi-
nates charging once the adjustable time limit has been
reached.
The MAX1737 regulates the voltage set point and charg-
ing current using two loops that work together to transi-
tion smoothly between voltage and current regulation. An
additional control loop monitors the total current drawn
from the input source to prevent overload of the input
supply, allowing the use of a low-cost wall adapter.
The per-cell battery voltage regulation limit is set
between +4.0V and +4.4V and can be set from one to
four by pin strapping. Battery temperature is monitored
by an external thermistor to prevent charging if the bat-
tery temperature is outside the acceptable range.
The MAX1737 is available in a space-saving 28-pin
QSOP package. Use the evaluation kit (MAX1737EVKIT)
to help reduce design time.
Ordering Information
PART
MAX1737EEI
TEMP RANGE
-40°C to +85°C
PIN-PACKAGE
28 QSOP
Applications
Notebook Computers
Hand-Held Instruments
Li+ Battery Packs
Desktop Cradle Chargers
INPUT SUPPLY
Typical Operating Circuit
DCIN
VL
CSSP
CSSN
DHI
Pin Configuration
TOP VIEW
VL 1
ISETIN 2
ISETOUT 3
THM 4
REF 5
GND 6
BATT 7
VADJ 8
CCV 9
CCS 10
CCI 11
CELL 12
TIMER1 13
TIMER2 14
28 DCIN
27 CSSP
26 CSSN
25 DHI
24 LX
REF
ISETIN
ISETOUT
CELL
VADJ
MAX1737
SYSTEM
LOAD
LX
BST
VLO
DLO
PGND
CS
R
S
BATT
Li+
BATTERY
1 TO 4
CELLS
MAX1737
23 BST
22 VLO
21 DLO
20 PGND
19 CS
18 SHDN
17 FULLCHG
16 FASTCHG
15 FAULT
ON
OFF
SHDN
GND
CCV
CCI
TIMER1
TIMER2
CCS
THM
FASTCHG
FULLCHG
FAULT
QSOP
________________________________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim's website at www.maxim-ic.com.
MAXIM [ MAXIM INTEGRATED PRODUCTS ]
