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8731AE Schematic ( PDF Datasheet ) - Maxim Integrated Products

Teilenummer 8731AE
Beschreibung MAX8731A
Hersteller Maxim Integrated Products
Logo Maxim Integrated Products Logo 




Gesamt 32 Seiten
8731AE Datasheet, Funktion
19-0756; Rev 0; 1/07
EVAALVUAAILTAIOBNLEKIT
SMBus Level 2 Battery Charger
with Remote Sense
General Description
The MAX8731A is an SMBus™ programmable multi-
chemistry battery charger. The MAX8731A uses a mini-
mal command set to easily program the charge voltage,
charge current, and adapter current limit.
The MAX8731A charges one to four Li+ series cells and
delivers up to 8A charge current. The MAX8731A drives
n-channel MOSFETs for improved efficiency and
reduced cost. Low-offset current-sense amplifiers pro-
vide high accuracy with 10mΩ sense resistors.
The MAX8731A 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 MAX8731A provides 0.5%
battery voltage accuracy directly at the battery terminal.
The MAX8731A provides a digital output that indicates
the presence of the AC adapter, as well as an analog out-
put that indicates the adapter current within 4% accuracy.
The MAX8731A 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 MAX8731A is avail-
able in a lead-free package.
SMBus is a trademark of Intel Corp.
Applications
Notebook Computers
Tablet PCs
www.DataMSheedeitc4aUl.cDomevices
Portable Equipment with Rechargeable Batteries
Pin Configuration
TOP VIEW
21 20 19 18 17 16 15
DCIN 22
LX 23
DHI 24
BST 25
VCC 26
CSSN 27
CSSP 28
MAX8731A
*EXPOSED PADDLE
14 BATSEL
13 ACOK
12 GND
11 VDD
10 SCL
9 SDA
8 IINP
1 234567
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
PIN-
PACKAGE
PKG
CODE
MAX8731AETI+
-40°C to +85°C
28 Thin QFN
(5mm x 5mm)
T2855-6
+Indicates a lead-free package.
Typical Operating Circuit
OPTIONAL
HOST
SCL
SDA
VDD
CSSP
ACIN
DCIN
ACOK
CSSN
DHI
LX
MAX8731A DLO
REF PGND
BST
CSIP
GND CSIN
BATSEL
SCL
SDA
VDD
FBSA
FBSB
GND LDO
VCC
IINP CCV
DAC CCS CCI
EXTERNAL LOAD
N
N
SELECTOR
BATSEL
BATTERY
A
BATTERY
B
THIN QFN
5mm x 5mm
________________________________________________________________ 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.






8731AE Datasheet, Funktion
SMBus Level 2 Battery Charger
with Remote Sense
ELECTRICAL CHARACTERISTICS
(VDCIN = VLX = VCSSP = VCSSN = 19V, VBST - VLX = 4.5V, VFBSA = VFBSB = VCSIP = VCSIN = 16.8V, BATSEL = GND = PGND = 0,
CLDO = 1µF, VCC = LDO, CREF = 1µF, CDAC = 0.1µF , VDD = 3.3V, ACIN = 2.5V; pins CCI, CCV, and CCS are compensated per
Figure 1; TA = -40°C to +85°C, unless otherwise noted.) (Note 2)
PARAMETER
CHARGE-VOLTAGE REGULATION
CONDITIONS
ChargingVoltage() = 0x41A0
Battery Full-Charge Voltage and
Accuracy
ChargingVoltage() = 0x3130
ChargingVoltage() = 0x20D0
ChargingVoltage() = 0x1060
CHARGE-CURRENT REGULATION
MIN TYP MAX UNITS
16.632
-1
12.466
-1
8.316
-1
4.129
-1.5
16.968
+1
12.717
+1
8.484
+1
4.255
+1.5
V
%
V
%
V
%
V
%
CSIP-to-CSIN Full-Scale Current-
Sense Voltage
78.22
83.05 mV
Charge Current and Accuracy
RS2, Figure 1 = 10mΩ;
ChargingCurrent()= 0x1f80
RS2, Figure 1 = 10mΩ;
ChargingCurrent() = 0x0f80
7.822
-3
3.809
-4
8.305
+3
4.126
+4
A
%
A
%
RS2, Figure 1 =10mΩ;
ChargingCurrent() = 0x0080
30 400 mA
Charge-Current Gain Error
Based on ChargeCurrent() = 128mA and 8.064A
-2
+2 %
FBSA/FBSB/CSIP/CSIN Input-
Voltage Range
0 19 V
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Battery Quiescent Current
Adapter present, not charging, ICSIP + ICSIN + ILX + IFBS,
VFBS_ = VLX = VCSIN = VCSIP = 19V
Adapter absent, ICSIP + ICSIN + ILX + IFBSA + IFBSB +
ICSSP + ICSSN, VFBS_= VLX = VCSIN = VCSIP = 19V,
VDCIN = 0V
5
µA
1
Adapter Quiescent Current
IDCIN +
ICSSP +
ICSSN
VAdapter = 26V, VBattery = 16.8V, not charging
VAdapter = 19V,
VBattery = 16.8V
Charging
Not charging
VAdapter = 8V,
VBattery = 4V
Charging
Not charging
500 µA
1 mA
500 µA
1 mA
500 µA
6 _______________________________________________________________________________________

6 Page









8731AE pdf, datenblatt
SMBus Level 2 Battery Charger
with Remote Sense
Typical Operating Characteristics (continued)
(Circuit of Figure 1, adapter = 19.5V, ChargeVoltage() = 16.8V, ChargeCurrent() = 3.854A, InputCurrent() = 3.584A, TA = +25°C,
unless otherwise noted.)
LDO LINE REGULATION
0
-1
-2
-3
-4
-5 NOT SWITCHING
-6
8
13 18
VDCIN (V)
23
0.20
0.15
0.10
0.05
0
-0.05
-0.10
-0.15
-0.20
0
REF LOAD REGULATION
NOT SWITCHING
0.2 0.4 0.6 0.8 1.0
IREF (mA)
REF ERROR vs. TEMPERATURE
0.3
0.2
0.1
0
-0.1
-0.2
-0.3
-40 -20
0 20 40 60
TEMPERATURE (°C)
80
SWITCHING FREQUENCY
450
400
350
300
250
www.DataSheet4U.com 200
150
0
5 10 15
VADAPTER - VBATTERY (V)
ADAPTER CURRENT
vs. ADAPTER VOLTAGE
3.0
SWITCHING, NO LOAD
2.5
20
2.0
ChargeVoltage( ) = 4.192V
1.5
1.0 NOT SWITCHING
0.5
BATTERY-CHARGE CURVE
5 MAX8731A toc20 13.0
2.8Ah x 3S3P BATTERY
4
BATTERY VOLTAGE
12.5
12.0
3
11.5
2
11.0
1 CHARGE CURRENT 10.5
0 10.0
0123456
TIME (h)
BATTERY-LEAKAGE CURRENT
vs. BATTERY VOLTAGE
2.5
ADAPTER PRESENT OR ABSENT
2.0
1.5
1.0
0.5
0
0 5 10 15 20 25 30
ADAPTER VOLTAGE (V)
0
0 5 10 15 20
BATTERY VOLTAGE (V)
12 ______________________________________________________________________________________

12 Page





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