MAX8731 Datasheet, PDF (1/32 Pages) Maxim Integrated Products – SMBus Level 2 Battery Charger with Remote Sense

19-3923; Rev 0; 1/06
EVAALVUAAILTAIOBNLEKIT
SMBus Level 2 Battery Charger with
Remote Sense
General Description
The MAX8731 is an SMBus™ programmable multichem-
istry battery charger. The MAX8731 uses a minimal
command set to easily program the charge voltage,
charge current, and adapter current limit.
The MAX8731 charges one to four Li+ series cells and
delivers up to 8A charge current. The MAX8731 drives
n-channel MOSFETs for improved efficiency and
reduced cost. Low-offset current-sense amplifiers pro-
vide high accuracy with 10mΩ sense resistors.
The MAX8731 current-sense amplifiers provide high
accuracy (3% at 3.5A) and also provide fast cycle-by-
cycle current-mode control to protect against battery
short circuit and system load transients.
The charger employs dual remote-sense, which reduces
charge time by measuring the feedback voltage directly
at the battery, improving accuracy of initial transition into
constant-voltage mode. The MAX8731 provides 0.5%
battery voltage accuracy directly at the battery terminal.
The MAX8731 provides a digital output that indicates the
presence of the AC adapter, as well as an analog output
that indicates the adapter current within 4% accuracy.
The MAX8731 is available in a small 5mm x 5mm,
28-pin, thin (0.8mm) QFN package. An evaluation kit is
available to reduce design time. The MAX8731 is avail-
able in lead-free packages.
SMBus is a trademark of Intel Corp.
Applications
Notebook Computers
Tablet PCs
Medical Devices
Portable Equipment with Rechargeable Batteries
Pin Configuration
TOP VIEW
21 20 19 18 17 16 15
DCIN 22
LX 23
DHI 24
BST 25
V_CC 26
CSSN 27
CSSP 28
MAX8731
*EXPOSED PADDLE
14 BATSEL
13 ACOK
12 GND
11 VDD
10 SCL
9 SDA
8 IINP
1 234567
THIN QFN
5mm x 5mm
Features
♦ 0.5% Battery Voltage Accuracy
♦ 3% Input Current-Limit Accuracy
♦ 3% Charge-Current Accuracy
♦ SMBus 2-Wire Serial Interface
♦ Cycle-by-Cycle Current Limit
Battery Short-Circuit Protection
Fast Response for Pulse Charging
Fast System-Load-Transient Response
♦ Dual-Remote-Sense Inputs
♦ Monitor Outputs for
Adapter Current (4% Accuracy)
AC Adapter Detection
♦ 11-Bit Battery Voltage Setting
♦ 6-Bit Charge-Current/Input-Current Setting
♦ 8A (max) Battery Charger Current
♦ 11A (max) Input Current
♦ +8V to +26V Input Voltage Range
♦ Charges Li+, NiMH, and NiCd Battery Chemistries
Ordering Information
PART
TEMP RANGE
MAX8731ETI+ -40°C to +85°C
+Indicates lead-free packaging.
PIN-PACKAGE
28 Thin QFN (5mm x 5mm)
Typical Operating Circuit
OPTIONAL
HOST
SCL
SDA
VDD
CSSP
ACIN
DCIN
ACOK
CSSN
DHI
LX
MAX8731 DLO
REF
PGND
BST
CSIP
GND
CSIN
FBSA
BATSEL
SCL
SDA
FBSB
VDD
GND
LDO
VCC
IINP
CCV
DAC CCS CCI
EXTERNAL
LOAD
N
N
SELECTOR
BATSEL
BATTERY
A
BATTERY
B
________________________________________________________________ Maxim Integrated Products 1
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