MAX1757 Datasheet, PDF (1/17 Pages) Maxim Integrated Products – Stand-Alone, Switch-Mode Li Battery Charger with Internal 14V Switch

19-1754; Rev 0; 6/00
EVAALVUAAILTAIOBNLEKIT
Stand-Alone, Switch-Mode
Li+ Battery Charger with Internal 14V Switch
General Description
The MAX1757 is a switch-mode lithium-ion (Li+) battery
charger that charges one to three cells. It provides a
regulated charging current accurate to ±10% and a
regulated 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 battery. The built-in safety timer automatical-
ly terminates charging once the adjustable time limit
has been reached.
The MAX1757 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 by automatically reducing battery-charging current
prevents overload of the input supply, 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 3 by pin strapping. Battery
temperature is monitored by an external thermistor to
prevent charging outside the acceptable temperature
range.
The MAX1757 is available in a space-saving 28-pin
SSOP package. Use the MAX1757EVKIT to help reduce
design time. For a stand-alone charger with a 28V
switch, refer to the MAX1758 data sheet. For a charger
controller capable of up to 4A charging current, refer to
the MAX1737 data sheet.
________________________Applications
Li+ Battery Packs
Notebook Computers
Hand-Held Instruments
PDAs
Desktop Cradle Chargers
Pin Configuration
TOP VIEW
Features
o Stand-Alone Charger for Up to 3 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 14V
o Up to 1.5A Programmable Charge Current
o Input Current Limiting
o Space-Saving 28-Pin SSOP
o 300kHz PWM Oscillator Reduces Noise
Ordering Information
PART
MAX1757EAI
TEMP. RANGE
-40°C to +85°C
PIN-PACKAGE
28 SSOP
Typical Operating Circuit
VIN
6V to 14V
DCIN
REF
CSSP
CSSN
HSD
LX
MAX1757
ISETOUT
BST
VL
ISETIN
CELL
PGND
CS
SYSTEM
LOAD
VL 1
ISETTIN 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
MAX1757
SSOP
28 DCIN
27 CSSP
26 CSSN
25 CCV
24 CCI
23 CCS
22 BST
21 CS
20 LX
19 LX
18 PGND
17 SHDN
16 FULLCHG
15 FASTCHG
VADJ
BATT
THM
CCS
CCI
ON
OFF
CCV
FASTCHG
TIMER1
FULLCHG
TIMER2
FAULT
SHDN
GND
THERM
Li+ BATTERY
1 TO 3 CELLS
________________________________________________________________ Maxim Integrated Products 1
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