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MAX8731ETI
Schematic [ru]
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Maxim MAX8731ETI Schematic [ru]

General Description
The MAX8731 is an SMBus™ programmable multichem­istry 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 pro­vide high accuracy with 10mΩ sense resistors.
The MAX8731 current-sense amplifiers provide high accuracy (3% at 3.5A) and also provide fast cycle-by­cycle 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 avail­able in lead-free packages.
Applications
Notebook Computers Tablet PCs Medical Devices Portable Equipment with Rechargeable Batteries
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
MAX8731
SMBus Level 2 Battery Charger with
Remote Sense
________________________________________________________________ Maxim Integrated Products 1
Ordering Information
Typical Operating Circuit
19-3923; Rev 0; 1/06
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.
SMBus is a trademark of Intel Corp.
+Indicates lead-free packaging.
EVALUATION KIT
AVAILABLE
Pin Configuration
TOP VIEW
DCIN
DHI
BST
V
CSSN
CSSP
22
LX
23
24
25
26
CC
27
28
12
PGND
DLO
CSIP
LDO
2021 19 17 16 15
*EXPOSED PADDLE
GND
ACIN
THIN QFN
5mm x 5mm
CSIN
18
MAX8731
4567
3
CCI
REF
CCS
FBSB
CCV
FBSA
DAC
14
BATSEL
ACOK
13
12
GND
V
11
DD
10
SCL
SDA
9
8
IINP
PART TEMP RANGE PIN-PACKAGE
MAX8731ETI+ -40°C to +85°C 28 Thin QFN (5mm x 5mm)
OPTIONAL
HOST
SCL SDA VDD
CSSP CSSN
ACIN DCIN ACOK
REF
GND
BATSEL SCL
SDA
V
DD
GND
IINP CCV
DAC
MAX8731
CCS
DHI
DLO
PGND
BST CSIP
CSIN
FBSA
FBSB
LDO
V
CCI
LX
CC
N
N
EXTERNAL
LOAD
SELECTOR
BATSEL
BATTERY A
BATTERY B
SMBus Level 2 Battery Charger with Remote Sense
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(V
DCIN
= VLX= V
CSSP
= V
CSSN
= 19V, V
BST
- VLX= 4.5V, V
FBSA
= V
FBSB
= V
CSIP
= V
CSIN
= 16.8V, BATSEL = GND = PGND = 0,
C
LDO
= 1µF, VCC= LDO, C
REF
= 1µF, C
DAC
= 0.1µF, VDD= 3.3V, ACIN = 2.5V; pins CCI, CCV, and CCS are compensated per
Figure 1; T
A
= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.)
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
DCIN, CSSN, CSIN, FBSA, FBSB to GND..............-0.3V to +28V
CSSP to CSSN, CSIP to CSIN, PGND to GND ......-0.3V to +0.3V
BST to GND ............................................................-0.3V to +32V
BST to LX..................................................................-0.3V to +6V
DHI to LX.................................................-0.3V to +(V
BST
+ 0.3)V
DLO to PGND..........................................-0.3V to +(LDO + 0.3)V
LX to GND .................................................................-6V to +28V
CCI, CCS, CCV, DAC, REF,
IINP to GND...........................................-0.3V to (V
VCC
+ 0.3)V
V
DD
, SCL, SDA, BATSEL, ACIN, ACOK, VCCto GND,
LDO to PGND ......................................................-0.3V to +6V
Continuous Power Dissipation (T
A
= +70°C)
28-Pin Thin QFN
(derate 20.8mW/°C above +70°C)........................1666.7 mW
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature......................................................+150°C
Storage Temperature Range .............................-60°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
MAX8731
PARAMETER CONDITIONS MIN TYP MAX UNITS
CHARGE-VOLTAGE REGULATION
ChargingVoltage() = 0x41A0
ChargingVoltage() = 0x3130
Battery Full-Charge Voltage and
Accuracy
ChargingVoltage() = 0x20D0
ChargingVoltage() = 0x1060
Battery Undervoltage-Lockout
Trip Point for Trickle Charge
2.5 V
CHARGE-CURRENT REGULATION
CSIP to CSIN Full-Scale Current-
Sense Voltage
78.22 80.64 83.06 mV
RS2 (Figure 1) = 10mΩ;
ChargingCurrent() = 0x1f80
Charge Current and Accuracy
RS2 (Figure 1) = 10mΩ;
ChargingCurrent() = 0x0f80
RS2 (Figure 1) = 10mΩ;
ChargingCurrent() = 0x0080 (128mA)
Charge-Current Gain Error Based on ChargeCurrent() = 128mA and 8.064A -2 +2 %
FBSA/FBSB/CSIP/CSIN
Input Voltage Range
0 19 V
16.716 16.8 16.884 V
-0.5 +0.5 %
12.491 12.592 12.693 V
-0.8 +0.8 %
8.333 8.4 8.467 V
-0.8 +0.8 %
4.15 4.192 4.234 V
-1.0 +1.0 %
7.822 8.064 8.306 A
-3 +3 %
3.809 3.968 4.126 A
-4 +4 %
64 400 mA
MAX8731
SMBus Level 2 Battery Charger with
Remote Sense
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(V
DCIN
= VLX= V
CSSP
= V
CSSN
= 19V, V
BST
- VLX= 4.5V, V
FBSA
= V
FBSB
= V
CSIP
= V
CSIN
= 16.8V, BATSEL = GND = PGND = 0,
C
LDO
= 1µF, VCC= LDO, C
REF
= 1µF, C
DAC
= 0.1µF, VDD= 3.3V, ACIN = 2.5V; pins CCI, CCV, and CCS are compensated per
Figure 1; T
A
= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.)
PARAMETER CONDITIONS MIN TYP MAX UNITS
Battery Quiescent Current
Adapter Quiescent Current
INPUT-CURRENT REGULATION CSSP to CSSN Full-Scale
Current-Sense Voltage
Input Current Accuracy
POR Input Current RS1 (Figure 1) = 10mΩ 256 mA Input Current-Limit Gain Error -2 +2 % Input Current-Limit Offset CSSP/CSSN Input Voltage Range 8 26 V IINP Transconductance V IINP Offset Based on V
IINP Accuracy
IINP Output Voltage Range 0 3.5 V SUPPLY AND LINEAR REGULATOR DCIN, Input Voltage Range 8.0 26.0 V
DCIN Undervoltage-Lockout
Trip Point
Power-Fail Threshold
Adapter present, not charging, I
V
Ad ap ter ab sent, I
+ I
I
DCIN
I
CSSP
I
CSSN
V
RS1 (Figure 1) = 10mΩ, InputCurrent() = 11004mA or
3584mA
= VLX = V
FBS_
, V
C S S N
FBS _
+
+
= 19V 106.7 110 113.3 mV
FBS_
CSIN
C S I P
= V
LX
V
Adapter
charging
V
Adapter
V
Battery
V
Adapter
V
Battery
= V
+ I = V
= 26V, V
= 19V,
= 16.8V
= 8V,
= 4V
CSIP
C S I N
C S I N
= 19V
+ I
= V
Battery
LX
CSIP
+ I
C S I P
+ I
CSIN
FBS A
= 19V , V
= 16.8V, not
+ I
FBS B
+ ILX + I
+ I
= 0V
D C I N
FBS,
C S S P
2 5
+1
200 500 µA
Charging 0.4 1 mA Not charging 200 500 µA Charging 0.4 1 mA Not charging 200 500 µA
-3 +3 %
RS1 (Figure 1) = 10mΩ, InputCurrent() = 2048mA -5 +5 %
Based on InputCurrent() = 1024mA and 11004mA
CSSP - CSSN
V
CSSP - CSSN
V
CSSP - CSSN
V
CSSP - CSSN
= 110mV 2.85 3.0 3.15 mA/V
CSSP - CSSN
= 110mV -5 +5 = 55mV or 35mV -4 +4 = 20mV -10 +10
= 110mV and 20mV -1.5 +1.5 mV
-1 +1 mV
DCIN falling 7 7.4 DCIN rising 7.5 7.85 V
- V
CSSP
V
CSSP
falling 9 15 21
CSIN
- V
rising 160 210 271
CSIN
µA
%
V
mV
MAX8731
SMBus Level 2 Battery Charger with Remote Sense
4 _______________________________________________________________________________________
ELECTRICAL CHARACTERISTICS (continued)
(V
DCIN
= VLX= V
CSSP
= V
CSSN
= 19V, V
BST
- VLX= 4.5V, V
FBSA
= V
FBSB
= V
CSIP
= V
CSIN
= 16.8V, BATSEL = GND = PGND = 0,
C
LDO
= 1µF, VCC= LDO, C
REF
= 1µF, C
DAC
= 0.1µF, VDD= 3.3V, ACIN = 2.5V; pins CCI, CCV, and CCS are compensated per
Figure 1; T
A
= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.)
PARAMETER CONDITIONS MIN TYP MAX UNITS
LDO Output Voltage 8.0V < V LDO Load Regulation 0 < I LDO Undervoltage-Lockout Threshold V V
Range 2.7 5.5 V
DD
V
UVLO Rising 2.5 2.7 V
DD
V
UVLO Hysteresis 100 mV
DD
V
Quiescent Current DCIN < 6V, VDD = 5.5V, SCL = SDA = 5.5V 16 27 µA
DD
REFERENCE REF Output Voltage 0 < I REF Undervoltage-Lockout Trip Point REF falling 3.1 3.9 V ACOK ACOK Sink Current V ACOK Leakage Current V ACIN ACIN Threshold 2.007 2.048 2.089 V ACIN Threshold Hysteresis 10 20 30 mV ACIN Input Bias Current -1 +1 µA REMOTE-SENSE INPUTS FBS_ Range V FBS_ Gain ∆V CSIN-FBS_ Clamp Voltage 225 250 275 mV FBS_ Bias Current Charger switching, FBS_ selected 14 µA FBS_ Bias Current Charger not switching or FBS_ not selected -2 +2 µA SWITCHING REGULATOR
Off-Time
BST Supply Current DHI high 500 800 µA LX Input Bias Current V
Maximum Discontinuous-Mode Peak
Current (I
MIN
)
DHI On-Resistance Low I DHI On-Resistance High I DLO On-Resistance High I DLO On-Resistance Low I
< 28V, no load 5.25 5.4 5.55 V
DCIN
< 30mA 34 100 mV
LDO
= 8.0V, V
DCIN
REF
= 0.4V, ACIN = 1.5V 1 mA
ACOK
= 5.5V, ACIN = 2.5V 1 µA
ACOK
- V
CSIN
/ ∆(V
CSIN
V
= 16.0V, V
CSIN
V
= 16.0V, V
CSIN
= 28V, V
DCIN
LDO
< 500µA 4.071 4.096 4.120 V
FBS
CSIN
CSIN
falling 3.20 4 5.15 V
0 200 mV
- V
) 0.95 1.00 1.05 V/V
FBS_
= 19V 360 400 440
CSSP
= 17V 260 300 360
CSSP
= VLX
= 20V, DHI low
2 µA
0.5 A
= -10mA 1 3 Ω
DHI
= 10mA 3 5 Ω
DHI
= 10mA 3 5 Ω
DLO
= -10mA 1 3 Ω
DLO
ns
ELECTRICAL CHARACTERISTICS (continued)
(V
DCIN
= VLX= V
CSSP
= V
CSSN
= 19V, V
BST
- VLX= 4.5V, V
FBSA
= V
FBSB
= V
CSIP
= V
CSIN
= 16.8V, BATSEL = GND = PGND = 0,
C
LDO
= 1µF, VCC= LDO, C
REF
= 1µF, C
DAC
= 0.1µF, VDD= 3.3V, ACIN = 2.5V; pins CCI, CCV, and CCS are compensated per
Figure 1; T
A
= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.)
MAX8731
SMBus Level 2 Battery Charger with
Remote Sense
_______________________________________________________________________________________ 5
ERROR AMPLIFIERS
GMV Amplifier Transconductance C har g i ng V ol tag e( ) = 16.8V , V
GMI Amplifier Transconductance ChargingCurrent() = 3968mA, V
GMS Amplifier Transconductance InputCurrent() = 3968mA, V
CCI/CCS/CCV Clamp Voltage
LOGIC LEVELS
SDA/SCL Input Low Voltage VDD = 2.7V to 5.5V 0.8
SDA/SCL Input High Voltage VDD = 2.7V to 5.5V 2.1
SDA/SCL Input Bias Current VDD = 2.7V to 5.5V -1 +1
BATSEL Input Low Voltage 0.8
BATSEL Input High Voltage 2.1
BATSEL Input Bias Current -1 +1
SDA, Output Sink Current V
SMBus TIMING SPECIFICATIONS (VDD = 2.7V to 5.5V) (see Figures 4 and 5)
SMBus Frequency f
Bus Free Time t
Start Condition Hold Time from SCL
Start Condition Setup Time from SCL
Stop Condition Setup Time from SCL
SDA Hold Time from SCL t
SDA Setup Time from SCL t
SCL Low Timeout t
SCL Low Period T
SCL High Period T
Maximum Charging Period Without a ChargeVoltage() or ChargeCurrent() Command
PARAMETER CONDITIONS
PARAMETERS SYMBOL CONDITIONS MIN TYP MAX UNITS
0.25V < V
(SDA)
t
t
t
TIMEOUT
< 2.0V
CCI/S/V
= 0.4V 6
SMB
BUF
HD:STA
SU:STA
SU:STO
HD:DAT
SU:DAT
(Note 1) 25 35
LOW
HIGH
FBS_
CSSP
= 16.8V
- V
CSIP
- V
CSSN
= 39.68mV
CSIN
= 79.36mV
MIN TYP MAX UNITS
0.0625 0.125 0.2500 mA/V
0.5
0.5
120
10 100
4.7
4
4.7
4
300
250
4.7
4
140 175 210
1
1
250
2.0
2.0
600
mA/V
mA/V
mV
V
V
µA
V
V
µA
mA
kHz
µs
µs
µs
µs
ns
ns
ms
µs
µs
s
MAX8731
SMBus Level 2 Battery Charger with Remote Sense
6 _______________________________________________________________________________________
ELECTRICAL CHARACTERISTICS
(V
DCIN
= VLX= V
CSSP
= V
CSSN
= 19V, V
BST
- V
LX
= 4.5V, V
FBSA
= V
FBSB
= V
CSIP
= V
CSIN
= 16.8V, BATSEL = GND = PGND = 0,
C
LDO
= 1µF, VCC= LDO, C
REF
= 1µF, C
DAC
= 0.1µF , VDD= 3.3V, ACIN = 2.5V; pins CCI, CCV, and CCS are compensated per
Figure 1; T
A
= -40°C to +85°C, unless otherwise noted.) (Note 2)
PARAMETER CONDITIONS
MIN
TYP
MAX
UNITS
CHARGE-VOLTAGE REGULATION
V
ChargingVoltage() = 0x41A0
-1 +1 % V
ChargingVoltage() = 0x3130
-1 +1 % V
ChargingVoltage() = 0x20D0
-1 +1 % V
Battery Full-Charge Voltage and
Accuracy
ChargingVoltage() = 0x1060
%
CHARGE-CURRENT REGULATION CSIP to CSIN Full-Scale Current-
Sense Voltage
mV
A
RS2 (Figure 1) = 10mΩ;
ChargingCurrent()= 0x1f80
-3 +3 % A
RS2 (Figure 1) = 10mΩ;
ChargingCurrent() = 0x0f80
-4 +4 %
Charge Current and Accuracy
RS2 (Figure 1) =10mΩ;
ChargingCurrent() = 0x0080
30
mA
Charge-Current Gain Error Based on ChargeCurrent() = 128mA and 8.064A -2 +2 % FBSA/FBSB/CSIP/CSIN Input
Voltage Range
0 19 V
Adapter present, not charging, I
CSIP
+ I
CSIN
+ ILX + I
FBS
,
V
FBS_
= VLX = V
CSIN
= V
CSIP
= 19V
5
Battery Quiescent Current
Adapter absent, I
CSIP
+ I
CSIN
+ ILX + I
FBSA
+ I
FBSB
+
I
CSSP
+ I
CSSN
, V
FBS_
= VLX = V
CSIN
= V
CSIP
= 19V,
V
DCIN
= 0V
1
µA
µA
Charging 1 mA
V
Adapter
= 19V,
V
Battery
= 16.8V
Not charging
µA
Charging 1 mA
Adapter Quiescent Current
I
DCIN
+
I
CSSP
+
I
CSSN
V
Adapter
= 8V,
V
Battery
= 4V
Not charging
µA
16.632
12.466
8.316
4.129
-1.5
78.22
7.822
3.809
V
A d a p t er
= 26V , V
= 16.8V , not char g i ng
B at te r y
16.968
12.717
8.484
4.255 +1.5
83.05
8.305
4.126
400
500
500
500
MAX8731
SMBus Level 2 Battery Charger with
Remote Sense
_______________________________________________________________________________________ 7
ELECTRICAL CHARACTERISTICS (continued)
(V
DCIN
= VLX= V
CSSP
= V
CSSN
= 19V, V
BST
- V
LX
= 4.5V, V
FBSA
= V
FBSB
= V
CSIP
= V
CSIN
= 16.8V, BATSEL = GND = PGND = 0,
C
LDO
= 1µF, VCC= LDO, C
REF
= 1µF, C
DAC
= 0.1µF , VDD= 3.3V, ACIN = 2.5V; pins CCI, CCV, and CCS are compensated per
Figure 1; T
A
= -40°C to +85°C, unless otherwise noted.) (Note 2)
PARAMETER CONDITIONS
UNITS
INPUT-CURRENT REGULATION
CSSP to CSSN Full-Scale
Current-Sense Voltage
V
FBS_
= 19V
mV
RS1 (Figure 1) = 10mΩ;
InputCurrent() = 11004mA or 3584mA
-6 +6
Input Current Accuracy
RS1 (Figure 1) = 10mΩ;
InputCurrent() = 2048mA
-5 +5
%
Input Current-Limit Gain Error Based on InputCurrent() = 1024mA and 11004mA -5 +5 % Input Current-Limit Offset Based on InputCurrent() = 1024mA and 11004mA -1 +1 mV
8 26 V
IINP Transconductance V
CSSP - CSSN
= 110mV 2.7 3.3
mA/V
IINP Offset Based on V
CSSP - CSSN
= 110mV and 20mV
mV
V
CSSP - CSSN
= 110mV -5 +5
V
CSSP - CSSN
= 55mV or 35mV -4 +4 IINP Accuracy
V
CSSP - CSSN
= 20mV -10
%
IINP Output Voltage Range 0 3.5 V SUPPLY AND LINEAR REGULATOR DCIN, Input Voltage Range 8.0
V
DCIN falling 7
DCIN Undervoltage-Lockout
Trip Point
DCIN rising
V
V
CSSP
- V
CSIN
falling 9 21
POWER_FAIL Threshold
V
CSSP
- V
CSIN
rising
mV
LDO Output Voltage 8.0V < V
DCIN
< 28V, no load
V
LDO Load Regulation 0 < I
LDO
< 30mA
mV
LDO Undervoltage-Lockout
Threshold
V
DCIN
= 8.0V, V
LDO
falling
V
V
DD
Range 2.7 5.5 V
V
DD
UVLO Rising 2.7 V
V
DD
Quiescent Current DCIN < 6V, VDD = 5.5V, SCL = SDA = 5.5V 27 µA
REFERENCE REF Output Voltage 0 < I
REF
< 500µA
V
REF Undervoltage-Lockout
Trip Point
REF falling 3.9 V
ACOK ACOK Sink Current V
ACOK
= 0.4V, ACIN = 1.5V 1 mA
MIN TYP MAX
CSSP/CSSN Input Voltage Range
103.3
-1.5
116.6
+1.5
+10
26.0
7.85
271
5.55 100
5.15
160
5.25
3.20
4.053
4.139
MAX8731
SMBus Level 2 Battery Charger with Remote Sense
8 _______________________________________________________________________________________
ELECTRICAL CHARACTERISTICS (continued)
(V
DCIN
= VLX= V
CSSP
= V
CSSN
= 19V, V
BST
- V
LX
= 4.5V, V
FBSA
= V
FBSB
= V
CSIP
= V
CSIN
= 16.8V, BATSEL = GND = PGND = 0,
C
LDO
= 1µF, VCC= LDO, C
REF
= 1µF, C
DAC
= 0.1µF , VDD= 3.3V, ACIN = 2.5V; pins CCI, CCV, and CCS are compensated per
Figure 1; T
A
= -40°C to +85°C, unless otherwise noted.) (Note 2)
PARAMETER CONDITIONS
UNITS
ACIN ACIN Threshold
V ACIN Threshold Hysteresis 10 30 mV REMOTE-SENSE INPUTS FBS_ Range V
CSIN
- V
FBS
0
mV
FBS_ Gain ∆V
CSIN
/ ∆(V
CSIN
- V
FBS_
) 0.9 1.1 V/V
CSIN-FBS_ Clamp Voltage
mV FBS_ Bias Current Charger switching, FBS_ selected 14 µA SWITCHING REGULATOR
V
CSIN
= 16.0V, V
CSSP
= 19V
Off-Time
V
CSIN
= 16.0V, V
CSSP
= 17V
ns
BST Supply Current DHI high
µA
DHI On-Resistance Low I
DHI
= -10mA 3 Ω
DHI On-Resistance High I
DHI
= 10mA 5 Ω
DLO On-Resistance High I
DLO
= 10mA 5 Ω
DLO On-Resistance Low I
DLO
= -10mA 3 Ω
ERROR AMPLIFIERS
C har g i ng V ol tag e( ) = 16.8V , V
FBS_
= 16.8V
mA/V
ChargingCurrent() = 3968mA, V
CSIP
- V
CSIN
= 39.68mV 0.5 2.0
mA/V
InputCurrent() = 3968mA, V
CSSP
- V
CSSN
= 79.36mV 0.5 2.0
mA/V
CCI/CCS/CCV Clamp Voltage 0.25V < V
CCI/S/V
< 2.0V
mV LOGIC LEVELS
SDA/SCL Input Low Voltage VDD = 2.7V to 5.5V 0.8 V
SDA/SCL Input High Voltage VDD = 2.7V to 5.5V 2.3 V BATSEL Input Low Voltage 0.8 V BATSEL Input High Voltage 2.3 V
SDA, Output Sink Current V
(SDA)
= 0.4V 6 mA
MIN TYP MAX
2.007
220
360 260
GMV Amplifier Transconductance GMI Amplifier Transconductance GMS Amplifier Transconductance
0.0625
150
2.089
200
280
440 350 800
0.2500
600
MAX8731
SMBus Level 2 Battery Charger with
Remote Sense
_______________________________________________________________________________________ 9
ELECTRICAL CHARACTERISTICS (continued)
(V
DCIN
= V
LX
= V
CSSP
= V
CSSN
= 19V, V
BST
- VLX= 4.5V, V
FBSA
= V
FBSB
= V
CSIP
= V
CSIN
= 16.8V, BATSEL = GND = PGND = 0,
C
LDO
= 1µF, VCC= LDO, C
REF
= 1µF, C
DAC
= 0.1µF , VDD= 3.3V, ACIN = 2.5V; pins CCI, CCV, and CCS are compensated
per Figure 1; T
A
= -40°C to +85°C, unless otherwise noted.) (Note 2)
SMB TIMING SPECIFICATION (VDD = 2.7V to 5.5V) (see Figures 4 and 5)
PARAMETERS
CONDITIONS
UNITS
SMBus Frequency f
SMB
10
kHz
Bus Free Time t
BUF
4.7 µs
Start Condition Hold Time from SCL
4 µs
Start Condition Setup Time from SCL
t
SU:STA
4.7 µs
Stop Condition Setup Time from SCL
4 µs
SDA Hold Time from SCL
ns
SDA Setup Time from SCL
ns
SCL Low Timeout
(Note 1) 25 35 ms
SCL Low Period T
LOW
4.7 µs
SCL High Period T
HIGH
4 µs
Maximum Charging Period Without a ChargeVoltage() or ChargeCurrent() Command
s
Note 1: Devices participating in a transfer will timeout when any clock low exceeds the 25ms minimum timeout period. Devices that
have detected a timeout condition must reset the communication no later than the 35ms maximum timeout period. Both a master and a slave must adhere to the maximum value specified as it incorporates the cumulative stretch limit for both a master (10ms) and a slave (25ms).
Note 2: Specifications to -40°C are guaranteed by design, not production tested.
SYMBOL
t
HD:STA
t
SU:STO
t
HD:DAT
t
SU:DAT
t
TIMEOUT
MIN TYP MAX
100
300
250
140 210
MAX8731
SMBus Level 2 Battery Charger with Remote Sense
10 ______________________________________________________________________________________
Typical Operating Characteristics
(Circuit of Figure 1, adapter = 19.5V, ChargeVoltage() = 16.8V, ChargeCurrent() = 3.854A, InputCurrent() = 3.584A, TA = +25°C, unless otherwise noted.)
INPUT CURRENT-LIMIT ERROR
vs. INPUT CURRENT-LIMIT SETTING
INPUT CURRENT-LIMIT SETTING (A)
INPUT CURRENT-LIMIT ERROR (%)
MAX8731 toc01
0246810
-6
-2
-4
0
2
4
6
MAXIMUM
MINIMUM
TYPICAL
INPUT CURRENT-LIMIT ERROR
vs. SYSTEM CURRENT
SYSTEM CURRENT (A)
INPUT CURRENT-LIMIT ERROR (%)
MAX8731 toc02
01234
-0.4
-0.2
0
0.2
0.4
INPUT CURRENT LIMIT = 2.048A
INPUT CURRENT LIMIT = 3.584A
INPUT CURRENT LIMIT = 4.096A
INPUT CURRENT-LIMIT ERROR
vs. SYSTEM CURRENT
SYSTEM CURRENT (A)
INPUT CURRENT-LIMIT ERROR (%)
MAX8731 toc03
01234
-1.0
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1.0
V
BATT
= 8.4V
V
BATT
= 16.8V
V
BATT
= 12.6V
INPUT CURRENT LIMIT = 3.584A
IINP ERROR vs. SYSTEM CURRENT
SYSTEM CURRENT (A)
IINP ERROR (%)
MAX8731 toc04
01.00.5 2.01.5 2.5 3.0 3.5 4.0
-1.0
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1.0
INPUT CURRENT LIMIT = 2.048A
INPUT CURRENT LIMIT = 3.584A
INPUT CURRENT LIMIT = 4.096A
OPERATING AT INPUT CURRENT LIMIT
IINP ERROR vs. SYSTEM CURRENT
SYSTEM CURRENT (A)
IINP ERROR (%)
MAX8731 toc05
01234
0
0.5
1.0
1.5
2.0
2.5
V
BATT
= 8.4V
V
BATT
= 12.6V
V
BATT
= 16.8V
INPUT CURRENT LIMIT = 3.584A
IINP ERROR vs. INPUT CURRENT
INPUT CURRENT (A)
IINP ERROR (%)
MAX8731 toc06
0123456
-10
-6
-8
-2
2
6
-4
0
4
8
10
MAXIMUM
MINIMUM
TYPICAL
NOT SWITCHING
CHARGE-CURRENT ERROR vs.
CHARGE CURRENT-LIMIT SETTING
CHARGE-CURRENT SETTING (A)
CHARGE-CURRENT LIMIT ERROR (%)
MAX8731 toc07
024 86
-10
-6
-8
-2
2
6
-4
0
4
8
10
MAXIMUM
MINIMUM
TYPICAL
CHARGE-CURRENT ERROR
vs. BATTERY VOLTAGE
BATTERY VOLTAGE (V)
CHARGE-CURRENT ERROR (%)
MAX8731 toc08
3 6 9 12 15 18
-4
-2
0
2
4
3.072A
3.968A
8.064A
TRICKLE-CHARGE CURRENT ERROR
vs. BATTERY VOLTAGE
BATTERY VOLTAGE (V)
TRICKLE-CHARGE CURRENT ERROR (%)
MAX8731 toc09
0 3 6 9 12 15 18
-30
-25
-20
-15
-10
-5
0
ChargeCurrent( ) = 128mA
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