MAX745 Datasheet, PDF (1/8 Pages) Maxim Integrated Products – Switch-Mode Lithium-Ion Battery-Charger

19-1182; Rev 2; 12/98
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Switch-Mode Lithium-Ion
Battery-Charger
General Description ____________________________Features
The MAX745 provides all functions necessary for
charging lithium-ion battery packs. It provides a regu-
lated charging current of up to 4A without getting hot,
and a regulated voltage with only ±0.75% total error at
the battery terminals. It uses low-cost, 1% resistors to
set the output voltage, and a low-cost N-channel MOS-
FET as the power switch.
The MAX745 regulates the voltage set point and charg-
ing current using two loops that work together to transi-
tion smoothly between voltage and current regulation.
The per-cell battery voltage regulation limit is set
between 4.0V and 4.4V using standard 1% resistors,
and then the number of cells is set from 1 to 4 by pin-
strapping. Total output voltage error is less than ±0.75%.
For a similar device with an SMBus™ microcontroller
interface and the ability to charge NiCd and NiMH cells,
refer to the MAX1647 and MAX1648. For a low-cost
lithium-ion charger using a linear-regulator control
scheme, refer to the MAX846A.
o Charges 1 to 4 Lithium-Ion Battery Cells
o ±0.75% Voltage-Regulation Accuracy
Using 1% Resistors
o Provides up to 4A without Excessive Heating
o 90% Efficient
o Uses Low-Cost Set Resistors and
N-Channel Switch
o Up to 24V Input
o Up to 18V Maximum Battery Voltage
o 300kHz PWM Operation: Low-Noise,
Small Components
o Stand-Alone Operation; No Microcontroller
Needed
________________________Applications
Lithium-Ion Battery Packs
Desktop Cradle Chargers
PART
MAX745C/D
Ordering Information
TEMP. RANGE
0°C to +70°C
PIN-PACKAGE
Dice*
Cellular Phones
Notebook Computers
Hand-Held Instruments
MAX745EAP
-40°C to +85°C 20 SSOP
Pin Configuration appears on last page.
*Dice are tested at T_A = +25°C.
___________________________________________________Typical Operating Circuit
V_IN
(UP TO 24V)
DCIN
VL
CELL
CELL0
BST
COUNT
SELECT
CELL1
DHI
MAX745
N
ON
LX
OFF
THM/SHDN
REF
DLO
N
SETI
VADJ
CS
SET PER
CELL VOLTAGE
WITH 1% RESISTORS
STATUS
BATT
CCV CCI GND IBAT PGND
I_CHARGE
R_SENSE
VOUT
1–4 Li+ CELLS
(UP TO 18V)
SMBus is a trademark of Intel Corp.
________________________________________________________________ Maxim Integrated Products 1
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