MAX17047G+T10 ,ModelGauge m3 Fuel GaugeApplicationsPackage or Tiny 0.4mm Pitch 9-Bump WLP Package2.5G/3G/4G Wireless Portable Game Players ..
MAX1705 ,1 to 3 Cell, High Current, Low-Noise, Step-Up DC-DC Converters with Linear RegulatorApplications __________Typical Operating CircuitDigital Cordless Phones PCS PhonesPersonal Communic ..
MAX17058G+T10 ,1-Cell/2-Cell Li+ ModelGauge ICsFeatures and BenefitsThe MAX17058/MAX17059 ICs are tiny fuel gauges S MAX17058: 1 Cell, MAX17059: 2 ..
MAX1705EEE ,1- to 3-Cell / High-Current / Low-Noise / Step-Up DC-DC Converters with Linear RegulatorELECTRICAL CHARACTERISTICS(V = V = V = 3.6V, CLK/SEL = FB = LBN = LBO = ONA = ONB = TRACK = GND, RE ..
MAX1705EEE ,1- to 3-Cell / High-Current / Low-Noise / Step-Up DC-DC Converters with Linear RegulatorApplications __________Typical Operating CircuitDigital Cordless Phones PCS PhonesPersonal Communic ..
MAX1705EEE ,1- to 3-Cell / High-Current / Low-Noise / Step-Up DC-DC Converters with Linear Regulatorapplications. They use a syn-chronous rectifier pulse-width-modulation (PWM) boost' Step-Up Output ..
MAX4524CUB ,Low-Voltage / Single-Supply Multiplexer and SwitchFeaturesThe MAX4524/MAX4525 are low-voltage, single-supply' Tiny 10-Pin µMAX PackageCMOS analog swi ..
MAX4524CUB ,Low-Voltage / Single-Supply Multiplexer and SwitchMAX4524/MAX452519-1332; Rev 0; 1/98Low-Voltage, Single-Supply Multiplexer and Switch ______________ ..
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MAX4524CUB+T ,Low-Voltage, Single-Supply Multiplexer and SwitchELECTRICAL CHARACTERISTICS—Single +5V Supply(V+ = 4.5V to 5.5V, GND = 0V, V = 2.4V, V = 0.8V, T = T ..
MAX4524CUB-T ,Low-Voltage, Single-Supply Multiplexer and SwitchApplicationsMAX4524EUB -40°C to +85°C 10 µMAX —Battery-Operated Equipment 10 TDFN-EP**MAX4524ETB -4 ..
MAX4524EUB ,Low-Voltage / Single-Supply Multiplexer and SwitchMAX4524/MAX452519-1332; Rev 0; 1/98Low-Voltage, Single-Supply Multiplexer and Switch ______________ ..
MAX17047G+T10
ModelGauge m3 Fuel Gauge
MAX17047/MAX17050
ModelGauge m3 Fuel Gauge
Simplified Operating Circuit
Ordering Information appears at end of data sheet.
For related parts and recommended products to use with this part,
refer to: www.maximintegrated.com/MAX17047.related
General Description
The MAX17047/MAX17050 incorporate the Maxim
ModelGauge™ m3 algorithm that combines the excellent
short-term accuracy and linearity of a coulomb counter
with the excellent long-term stability of a voltage-based fuel
gauge, along with temperature compensation to provide
industry-leading fuel-gauge accuracy. ModelGauge m3
cancels offset accumulation error in the coulomb counter,
while providing better short-term accuracy than any purely
voltage-based fuel gauge. Additionally, the ModelGauge
m3 algorithm does not suffer from abrupt corrections that
normally occur in coulomb-counter algorithms, since tiny
continual corrections are distributed over time.
The device automatically compensates for aging, tem-
perature, and discharge rate and provides accurate state
of charge (SOC) in mAh or %, as well as time-to-empty
over a wide range of operating conditions. The device
provides two methods for reporting the age of the bat-
tery: reduction in capacity and cycle odometer.
The device provides precision measurements of current,
voltage, and temperature. Temperature of the battery
pack is measured using an external thermistor supported
by ratiometric measurements on an auxiliary input. A
2-wire (I2C) interface provides access to data and control
registers. The MAX17047 is available in a lead(Pb)-free,
3mm x 3mm, 10-pin TDFN package. The MAX17050 is
available in a 0.4mm pitch 9-bump WLP package.
Applications
Features
S Accurate Battery-Capacity and Time-To-Empty
Estimation Temperature, Age, and Rate Compensated Does Not Require Empty, Full, or Idle States to Maintain Accuracy
S Precision Measurement System No Calibration Required
S ModelGauge m3 Algorithm Long-Term Influence by Voltage Fuel Gauge Cancels Coulomb-Counter Drift Short-Term Influence by Coulomb Counter Provides Excellent Linearity Adapts to Cell Characteristics
S External Temperature-Measurement Network Actively Switched Thermistor Resistive Divider Reduces Current Consumption
S Low Quiescent Current 25µA Active, < 0.5µA Shutdown
S Alert Indicator for SOC, Voltage, Temperature, and
Battery Removal/Insertion Events
S AtRate Estimation of Remaining Capacity
S 2-Wire (I2C) Interface
S Tiny, Lead(Pb)-Free, 3mm x 3mm, 10-Pin TDFN
Package or Tiny 0.4mm Pitch 9-Bump WLP Package2.5G/3G/4G Wireless
Handsets
Smartphones/PDAs
Tablets and Handheld
Computers
Portable Game Players
e-Readers
Digital Still and Video
Cameras
Portable Medical Equipment
0.1µF0.1µFOPTIONAL
10nF
OPTIONAL
10kI
PK-
PK+
OPTIONAL
10kI
NTC
THERMISTOR10mI
RSNS
CSP
REG
AINSCL
THRM
VBATT
VTT
(MAX17047 ONLY)
CSNEP
SDA
ALRT
MAX17047
MAX17050
PROTECTION
SYSTEMBATTERY PACK
HOST
MAX17047/MAX17050
ModelGauge m3 Fuel Gauge
VBATT, SDA, SCL, ALRT to CSP .............................-0.3V to +6V
REG to CSP ..........................................................-0.3V to +2.2V
VTT to CSP ...............................................................-0.3V to +6V
THRM, AIN to CSP .....................................-0.3V to (VTT + 0.3V)
CSN to CSP ................................................................-2V to +2V
Continuous Sink Current (VTT) ...........................................20mA
Continuous Sink Current (SCL, SDA, ALRT) ......................20mA
Continuous Power Dissipation (TA = +70NC)TDFN (derate 24.4mW/NC above +70NC) ...............1951.2mWWLP (derate 11.9mW/NC above +70NC)...................952.0mW
Operating Temperature Range ..........................-40NC to +85NC
Junction Temperature .....................................................+150NC
Storage Temperature Range ............................-55NC to +125NC
Lead Temperature (soldering 10s) .................................+300NC
Soldering Temperature (reflow) ......................................+260NC
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(VBATT = 2.5V to 4.5V, TA = -20NC to +70NC, unless otherwise noted. Typical values are at TA = +25NC.) (Note 2)
TDFN
Junction-to-Ambient Thermal Resistance (qJA) ..........41°C/W
Junction-to-Case Thermal Resistance (qJC) .................9°C/W
WLP
Junction-to-Ambient Thermal Resistance (qJA) ..........84°C/W
Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-layer
board. For detailed information on package thermal considerations, refer to www.maximintegrated.com/thermal-tutorial.
PACKAGE THERMAL CHARACTERISTICS(Note 1)
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional opera-
tion 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.
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITS
Supply VoltageVBATT(Note 3)2.54.5V
Supply CurrentIDD0Shutdown mode, TA P +50NC0.52FAIDD1Active mode, average current2542
REG Regulation VoltageVREG1.51.9V
Measurement Error, VBATTVGERRTA = +25NC-7.5+7.5mV-20+20
Measurement Resolution, VBATTVLSb0.625mV
VBATT Measurement RangeVFS2.54.98V
Input Resistance CSN, AIN15MI
Ratiometric Measurement
Accuracy, AINTGERR-0.5+0.5%
Ratiometric Measurement
Resolution, AINTLSb0.0244% Full
Scale
Current Register ResolutionILSb1.5625FV
Current Full-Scale MagnitudeIFSQ51.2mV
Current Offset ErrorIOERRQ1.5FV
Current Gain ErrorIGERR-1+1% of
Reading
Time-Base AccuracytERR
VDD = 3.6V at TA = +25NC-1+1TA = 0NC to +50NC-2.5+2.5
TA = -20NC to +70NC-3.5+3.5
MAX17047/MAX17050
ModelGauge m3 Fuel Gauge
ELECTRICAL CHARACTERISTICS (continued)
(VBATT = 2.5V to 4.5V, TA = -20NC to +70NC, unless otherwise noted. Typical values are at TA = +25NC.) (Note 2)
ELECTRICAL CHARACTERISTICS (2-WIRE INTERFACE)
(2.5V P VBATT P 4.5V, TA = -20NC to +70NC.) (Note 2)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITS
THRM Output DriveIOUT = 0.5mAVTT - 0.1V
THRM Precharge TimetPRE8.48ms
SDA, SCL, ALRT
Input Logic HighVIH1.5V
SDA, SCL, ALRT Input Logic LowVIL 0.5V
SDA, ALRT Output Logic LowVOLIOL = 4mA 0.4V
SDA, ALRT Pulldown CurrentIPDActive mode, VSDA = 0.4V, VALRT = 0.4V0.050.20.4FA
ALRT Leakage1FA
THRM Operating Range 2.5VTTV
Battery-Removal Detection
Threshold—VAIN RisingVDETRVTHRM - VAIN40125200mV
Battery-Removal Detection
Threshold—VAIN FallingVDETFVTHRM - VAIN70150230mV
Battery-Removal Detection
Comparator DelaytTOFF
VAIN step from 70% to 100% of VTHRM to
ALRT falling; Alrtp = logic 0;
EnAIN = logic 1; FTHRM = logic 1
100Fs
External AIN CapacitanceRTHM = 10kI NTC100nF
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITS
SCL Clock FrequencyfSCL(Note 4)0400kHz
Bus Free Time Between a STOP
and START ConditiontBUF1.3Fs
Hold Time (Repeated)
START ConditiontHD:STA(Note 5)0.6Fs
Low Period of SCL ClocktLOW1.3Fs
High Period of SCL ClocktHIGH0.6Fs
Setup Time for a Repeated
START ConditiontSU:STA0.6Fs
Data Hold TimetHD:DAT(Notes 6, 7)00.9Fs
Data Setup TimetSU:DAT(Note 6)100ns
Rise Time of Both SDA and SCL
SignalstR20 +
0.1CB300ns
MAX17047/MAX17050
ModelGauge m3 Fuel Gauge
I2C Bus Timing Diagram
Figure 1. I2C Bus Timing Diagram
Note 2: Specifications are 100% tested at TA = +25°C. Limits over the operating range are guaranteed by design and
characterization.
Note 3: All voltages are referenced to CSP.
Note 4: Timing must be fast enough to prevent the device from entering shutdown mode due to bus low for a period > 45s minimum.
Note 5: fSCL must meet the minimum clock low time plus the rise/fall times.
Note 6: The maximum tHD:DAT has only to be met if the device does not stretch the low period (tLOW) of the SCL signal.
Note 7: This device internally provides a hold time of at least 100ns for the SDA signal (referred to the minimum VIH of the SCL
signal) to bridge the undefined region of the falling edge of SCL.
Note 8: Filters on SDA and SCL suppress noise spikes at the input buffers and delay the sampling instant.
Note 9: CB—total capacitance of one bus line in pF.
ELECTRICAL CHARACTERISTICS (2-WIRE INTERFACE) (continued)
(2.5V P VBATT P 4.5V, TA = -20NC to +70NC.) (Note 2)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITS
Fall Time of Both SDA and SCL
SignalstF20 +
0.1CB300ns
Setup Time for STOP ConditiontSU:STO0.6Fs
Spike Pulse Widths
Suppressed by Input FiltertSP(Note 8)050ns
Capacitive Load for Each Bus
LineCB(Note 9)400pF
SCL, SDA Input CapacitanceCBIN60pF
SDA
SCL
tLOW
tHD:STA
tHD:DAT
tSU:STAtSU:STO
tSU:DATtHD:STA
tSPtRtBUF
SSrPS
MAX17047/MAX17050
ModelGauge m3 Fuel Gauge
Typical Operating Characteristics
(TA = +25°C, unless otherwise noted.)
SHUTDOWN CURRENT
vs. SUPPLY VOLTAGE
MAX17047 toc01
VBATT (V)
SHUTDOWN CURRENT (uA)4123
TA = +70°C
TA = +25°C
TA = -20°C
ACTIVE CURRENT vs. SUPPLY VOLTAGE
MAX17047 toc02
VBATT (V)
ACTIVE CURRENT (uA)4321
TA = +25°C
TA = +70°C
TA = -20°C
VOLTAGE ADC ERROR vs. TEMPERATURE
AND SUPPLY VOLTAGE
MAX17047 toc03
VBATT (V)
VOLTAGE ADC ERROR (mV)
TA = -20°C
TA = +70°C
TA = +25°C
CURRENT ADC ERROR
vs. TEMPERATURE
MAX17047 toc04
CURRENT FORCED (A)
CURRENT ADC ERROR (mA)0-1
TA = +25°CTA = +70°C
TA = -20°C
RESPONSE TO TEMPERATURE TRANSIENT
AT CONSTANT-CURRENT LOAD
MAX17047 toc06
SOC (%), TEMPERATURE (°C)21
CELL
(V)
VCELL RISES WITH
TEMPERATURE DURING
CONSTANT LOAD
FUEL GAUGE CHANGES
TRAJECTORY AFTER
TEMPERATURE CHANGE
EMPTY VOLTAGE
SOCREP
SOCAV
TEMPERATURE
AUXILIARY INPUT ADC ERROR
vs. TEMPERATURE
MAX17047 toc05
AIN RATIO TO VTT (%)
AUXILIARY INPUT ADC ERROR (%)8060702030405010
TA = +25°C
TA = -20°C
TA = +70°C
END OF CHARGE DETECTION
MAX17047 toc07
CAPACITY (mAh); CURRENT (mA)42
FULLCAP
CELL
(V)
VALID END-OF-CHARGE
DETECTION EVENT
REMCAPREP
VCELL
NEAR-FULL FALSE
CHARGE TERMINATION
EVENTS REJECTED
CURRENT
MAX17047/MAX17050
ModelGauge m3 Fuel Gauge
Typical Operating Characteristics (continued)
(TA = +25°C, unless otherwise noted.)
COLD DISCHARGE (0°C)
MAX17047 toc08
TIME (Hr)
STATE OF CHARGE (%)642
ERROR (%)
REFERENCE
SOC
SOCREP
ERROR
CHARGE AND DISCHARGE AT +20°C
TIME (Hr)
STATE OF CHARGE (%)
ERROR (%)5
ERROR
MAX17047 toc10
C/2 DISCHARGESOCREP
REFERENCE
SOC
C/4 DISCHARGE
C/7 DISCHARGE
C/9 DISCHARGE
DISCHARGE AT +40°C
MAX17047 toc09
TIME (Hr)
STATE OF CHARGE (%)642
ERROR (%)
C/4 DISCHARGE
C/7 DISCHARGE
C/9 DISCHARGE
REFERENCE
SOC
SOCREP
ERROR
CHARGE AND DISCHARGE IN
ACTUAL SYSTEM
TIME (Hr)
STATE OF CHARGE (%) OR TEMPERATURE (°C)
CELL
(V5
VCELL
REFERENCE SOC (%)
MAX17047 toc11
SOCREP (%)
TEMPERATURE
MAX17047/MAX17050
ModelGauge m3 Fuel Gauge
Pin/Bump Descriptions
Pin/Bump Configurations
PINBUMPNAMEFUNCTIONTDFNWLP—VTT
Supply Input for Thermistor Bias Switch (MAX17047 Only.) VTT is connected internally to VBATT
on the MAX17050. Connect to supply for ratiometric AIN pin-voltage measurements. In most
applications, connect VTT to VBATT.A1AINAuxiliary Voltage Input. Auxiliary voltage input from external thermal-measurement network. AIN
also provides battery insertion/removal detection. Connect to VBATT, if not used.A2SCLSerial Clock Input. 2-wire clock line. Input only.C1SDASerial Data Input/Out. 2-wire data line. Open-drain output driver.A3CSNSense Resistor Connection. System ground connection and sense resistor input.C3CSPChip Ground and Sense Resistor InputB3REGVoltage Regulator Bypass. Connect a 0.1FF capacitor from REG to CSP.B2ALRT
Alert Indication. An open-drain n-channel output used to indicate specified condition thresholds
have been met. A 200kI pullup resistor to power rail is required for use as an output. Alternatively,
ALRT can operate as a shutdown input with the output function disabled.C2THRMThermistor Bias Connection. Supply for thermistor resistor-divider. Connect to the high side of the
thermistor/resistor-divider. THRM connects internally to VTT during temperature measurement. B1VBATTPower-Supply and Battery Voltage-Sense Input. Kelvin connect to positive terminal of battery pack.
Bypass with a 0.1FF capacitor to CSP.—EPExposed Pad (TDFN Only). Connect to CSP.
VBATT
ALRT
REG
VTT
SCL
SDA
MAX17047THRMAINCSPCSN
TDFNTOP VIEW
WLPMAX17050
AIN
VBATT
SDATHRMCSP
ALRTREG
CSNSCL
MAX17047/MAX17050
ModelGauge m3 Fuel Gauge
Block Diagram
Detailed Description
The MAX17047/MAX17050 incorporate the Maxim
ModelGauge m3 algorithm that combines the excellent
short-term accuracy and linearity of a coulomb counter
with the excellent long-term stability of a voltage-based
fuel gauge, along with temperature compensation to pro-
vide industry-leading fuel-gauge accuracy. ModelGauge
m3 cancels offset accumulation error in the coulomb
counter, while providing better short-term accuracy than
any purely voltage-based fuel gauge. Additionally, the
ModelGauge m3 algorithm does not suffer from abrupt
corrections that normally occur in coulomb-counter algo-
rithms, since tiny continual corrections are distributed
over time.
The device automatically compensates for aging, tem-
perature, and discharge rate and provides accurate
state-of-charge (SOC) in mAh or % over a wide range of
operating conditions. The device provides two methods
for reporting the age of the battery: reduction in capacity
and cycle odometer.
The device provides precision measurements of current,
pack is measured using an external thermistor supported
by ratiometric measurements on an auxiliary input. A
2-wire (I2C) interface provides access to data and control
registers. The MAX17047 is available in a 3mm x 3mm,
10-pin TDFN package. The MAX17050 is available in a
0.4mm pitch 9-bump WLP package.
ModelGauge m3 Algorithm
The ModelGauge m3 algorithm combines a high-accura-
cy coulomb counter with a voltage fuel gauge (VFG) as
represented in Figure 2.
Classical coulomb-counter-based fuel gauges have
excellent linearity and short-term performance. However,
they suffer from drift due to the accumulation of the offset
error in the current-sense measurement. Although the
offset error is often very small, it cannot be eliminated,
causes the reported capacity error to increase over
time, and requires periodic corrections. Corrections are
usually performed at full or empty. Some other systems
also use the relaxed battery voltage to perform correc-
tions. These systems determine the SOC based on the
battery voltage after a long time of no current flow. Both
0.1µF
PK-
PK-
CSP
PK-PK-SYSTEM GROUND
PK+
PK+
10nF
0.1µF
10mI
RSNS
32kHz OSCILLATOR
OCV CALCULATION
ModelGauge m3
ALGORITHM2V LDO
VBATT
VBATT
REG
SDA
ALRT
SCL
VTT
(MAX17047 ONLY)
THRM
VTHRM - VDETR/VDETFBATTERY
REMOVAL
REF
DETECT
CSPCSN
AIN
OUT
MUX12-BIT ADCI2C
INTERFACE
REF ADC
MAX17047
MAX17050
MAX17047/MAX17050
ModelGauge m3 Fuel Gauge
observed over time in the actual application, the error in
the system is boundless. The performance of classic
coulomb counters is dominated by the accuracy of such
corrections.
Classical voltage-measurement-based SOC estimation
has poor accuracy due to inadequate cell modeling, but
does not accumulate offset error over time.
The device includes an advanced VFG, which estimates
open-circuit voltage (OCV), even during current flow, and
simulates the nonlinear internal dynamics of a lithium-ion
(Li+) battery to determine the SOC with improved accu-
racy. The model considers the time effects of a battery
caused by the chemical reactions and impedance in the
battery to determine SOC based on table lookup. This
SOC estimation does not accumulate offset error over time.
The ModelGauge m3 algorithm combines a high-accu-
combined result eliminates the weaknesses of both the
coulomb counter and the VFG, while providing the
strengths of both. A mixing algorithm combines the VFG
capacity with the coulomb counter and weighs each
result so that both are used optimally to determine the
battery state. In this way, the VFG capacity result is used
to continuously make small adjustments to the battery
state, canceling the coulomb-counter drift.
The ModelGauge m3 algorithm uses this battery state
information and accounts for temperature, battery cur-
rent, age, and application parameters to determine the
remaining capacity available to the system.
The ModelGauge m3 algorithm continually adapts to the
cell and application through independent learning rou-
tines. As the cell ages, its change in capacity is monitored
and updated and the VFG dynamics adapt based on cell-
Figure 2. ModelGauge m3 Overview
EMPTY
DETECTION
CURRENT
TIMERELAXED
CELL
DETECTION
CAPACITY LEARNmAh PER %
VOLTAGE FUEL GAUGE
CURRENT
TEMPERATURE
COULOMB COUNTERmAh OUTPUT
MIXING ALGORITHMmAh OUTPUT
RemCapMIX
SOCMIX
APPLICATION
EMPTY
COMPENSATION
END-OF-CHARGE
DETECTION
APPLICATION
OUTPUTS:
CELL CHEMISTRY
OUTPUTS:SOCREP
RemCapREP
SOCAV
RemCapAV
TTE
FullCAP
OCV
CYCLES
RCELL
FullCAPNom
AGE
OCV TEMPERATURE-
COMPENSATION LEARN
VOLTAGE
OCV TABLE LOOKUP% REMAINING OUTPUT
OCV CALCULATIONOCV OUTPUT
MAX17047/MAX17050
ModelGauge m3 Fuel Gauge
OCV Estimation and Coulomb-Count Mixing
The core of the ModelGauge m3 algorithm is a mixing
algorithm that combines the OCV state estimation with
the coulomb counter. After power-on reset of the IC,
coulomb-count accuracy is unknown. The OCV state
estimation is weighted heavily compared to the coulomb-
count output. As the cell progresses through cycles in
the application, coulomb-counter accuracy improves
and the mixing algorithm alters the weighting so that
the coulomb-counter result is dominant. From this point
forward, the IC switches to servo mixing. Servo mixing
provides a fixed magnitude continuous error correction to
the coulomb count, up or down, based on the direction
of error from the OCV estimation. This allows differences
between the coulomb count and OCV estimation to be
corrected quickly. See Figure 3.
The resulting output from the mixing algorithm does
not suffer drift from current measurement offset error
and is more stable than a stand-alone OCV estimation
algorithm; see Figure 4. Initial accuracy depends on the
relaxation state of the cell. The highest initial accuracy is
achieved with a fully relaxed cell.
Fuel-Gauge Empty Compensation
As the temperature and discharge rate of an applica-
tion changes, the amount of charge available to the
applica tion also changes. The ModelGauge m3 algo-
rithm dis tinguishes between remaining capacity of the
cell (RemCapMIX) and remaining capacity of the appli-
cation (RemCapAV) and reports both results to the user.
Fuel-Gauge Learning and Age Support
The device periodically makes internal adjustments
to cell characterization and application information to
remove initial error and maintain accuracy as the cell
ages. These adjustments always occur as small under-
corrections to prevent instability of the system and
prevent any noticeable jumps in the fuel-gauge outputs.
Learning occurs automatically without any input from the
host. To maintain learned accuracy through power loss,
the host must periodically save learned information and
then restore after power is returned. See the Power-Up
and Power-On Reset section for details:Full Capacity Available to Application (FullCAP).
This is the total capacity available to the application
at full. FullCAP is updated near the end of charging
when termination is detected. See the End-of-Charge
Detection section.
Figure 3. ModelGauge m3 OCV and Coulomb-Count Mixing
CELL CYCLES
OCV AND COULOMB-COUNT
MIXING RATIO
100%
COULOMB-COUNT INFLUENCESERVO MIXING
OCV
INFLUENCE
TIME
STATE-OF-CHARGE ERROR
(SHADED AREA)
ModelGauge m3
OCV + COULOMB-COUNT MIXING
MAXIMUM ERROR RANGE
MAXIMUM COULOMB-COUNTER ERROR
TYPICAL OCV ESTIMATION
ERROR AS CELL IS CYCLED
MAX17047/MAX17050
ModelGauge m3 Fuel GaugeCell Capacity (FullCapNom). This is the total cell
capacity at full, according to the VFG. This includes
some capacity that is not available to the application
at high loads and/or low temperature. The device
periodically compares percent change based on OCV
measurement vs. coulomb-count change as the cell
charges and discharges. This information allows the
device to maintain an accurate estimation of the cell’s
capacity in mAh as the cell ages.Voltage Fuel-Gauge Adaptation. The device
observes the battery’s relaxation response and
adjusts the dynamics of the VFG. This adaptation
adjusts the RCOMP0 register during qualified cell
relaxation events.Empty Learning. The device updates internal
data whenever cell empty is detected (VCELL <
V_empty) to account for cell age or other cell devia-
tions from the characterization information. This main-
tains SOC accuracy as the battery ages.
Determining Fuel-Gauge Accuracy
To determine the true accuracy of a fuel gauge, as expe-
rienced by end users, the battery should be exercised
in a dynamic manner. The end-user accuracy cannot be
understood with only simple cycles.
To challenge a correction-based fuel gauge, such as
a coulomb counter, test the battery with partial loading
sessions. For example, a typical user may operate the
device for 10min and then stop use for an hour or more.
A robust test method includes these kinds of sessions
many times at various loads, temperatures, and duration.
Refer to Application Note 4799: Cell Characterization
Procedure for a ModelGauge m3 Fuel Gauge.
Initial Accuracy
The device uses the first voltage reading after power-up
or after cell insertion to determine the starting output of
the fuel gauge. It is assumed that the cell is fully relaxed
prior to this reading; however, this is not always the
case. If the cell was recently charged or discharged, the
voltage measured by the device may not represent the
true state of charge of the cell, resulting in initial error in
the fuel gauge outputs. In most cases, this error is minor
and is quickly removed by the fuel gauge algorithm dur-
ing normal operation.
Typical Operating Circuit
The device is designed to mount outside the cell pack
that it monitors. Voltage of the battery pack is measured
directly at the pack terminals by the VBATT and CSP
connections. Current is measured by an external sense
resistor placed between the CSP and CSN pins. An
external resistor-divider network allows the device to
measure temperature of the cell pack by monitoring the
AIN pin. The THRM pin provides a strong pullup for the
resistor-divider that is internally disabled when tempera-
ture is not being measured.
Communication to the host occurs over a standard I2C
interface. SCL is an input from the host, and SDA is an
open-drain I/O pin that requires an external pullup. The
ALRT pin is an output that can be used as an external
interrupt to the host processor if certain application con-
ditions are detected. ALRT can also function as an input,
allowing the host to shut down the device. This pin is
also open drain and requires an external pullup resistor.
Figure 5 is the typical operating circuit.
Multicell Circuit
The MAX17047 can be used in multicell pack applica-
tions. A resistor-divider network divides the pack voltage
down so that the IC monitors the equivalent voltage of a
single cell. The MAX9910 buffers the divider output so
that loading by the MAX17047 does not affect accuracy.
VTT must be connected to a regulated supply in the sys-
tem to prevent overloading the MAX9910. Contact the
factory for a MAX17050 multicell application circuit. See
Figure 6.
Thermistor Sharing Circuit
The MAX17047 can share the cell thermistor circuit
with the system charger. In this circuit, there is a single
thermistor inside the cell pack and a single bias resistor
external to the cell pack. The device shares the same
external bias as the charger circuit and measurement
point on the thermistor. In this configuration, each device
can measure temperature individually or simultaneously
without interference. Alternatively, if the bias voltage in
the charger circuit is not available to the device, a sepa-
rate bias voltage on the VTT pin can be used. For proper
operation, the separate bias voltage must be larger than
the minimum operating voltage of the device, but no
larger than one diode drop above the charger circuit
bias voltage. The MAX17050 cannot be operated in his
configuration. See Figure 7.
MAX17047/MAX17050
ModelGauge m3 Fuel Gauge
Figure 5. Typical Operating Circuit
Figure 6. Multicell Application Circuit
0.1µF0.1µFOPTIONAL
10nF
OPTIONAL
10kI
PK-
PK+
OPTIONAL
10kI
NTC
THERMISTOR10mI
RSNS
CSP
REG
AINSCL
THRM
VBATT
VTT
(MAX17047 ONLY)
CSNEP
SDA
ALRT
MAX17047
MAX17050
OPTIONAL
200kI
OPTIONAL
5kI
SYSTEMBATTERY PACK
HOSTPROTECTION IC
THERMISTOR
MEASUREMENT OPTIONAL
MAX170473.3nF
4.5V-5.5V
REGULATOR
SYSTEM
MAX9910
0.1µF
OPTIONAL
10kI
OPTIONAL
200kI
SYSTEM
GROUND
10mI
OPTIONAL
5kI
OPTIONAL
10nF
THRM
ALRT
VTT
AINCSPEP
0.1µF
VBATT
PK-
PK-
PK+
1MI
N-1
PK-
100I
47kI
SDA
SCL
CSN
BATTERY PACK
CELL N
CELL 1
OPTIONAL
10k NTC
THERMISTOR
PROTECTOR
HOST
MAX17047/MAX17050
ModelGauge m3 Fuel Gauge
Figure 7. Operating Circuits that Share Pack Thermistor with System Charger
Recommended Layout
Proper circuit layout (see Figure 8) is essential for
measurement accuracy when using the MAX17047/
MAX17050 ModelGauge m3 ICs. The recommended
layout guidelines are as follows:
1) Mount RSNS as close as possible to PACK-. The
device shares both voltage and current measure-
ments on the CSP pin. Therefore, it is important to limit
the amount of trace resistance between the current-
sensing resistor and PACK-.
2) VBATT trace should make a Kelvin connection to
PACK+. The device shares the VBATT pin for both
voltage measurement and IC power. Limiting the
voltage loss through this trace is important to voltage-
measurement accuracy. PCB resistance that cannot
be removed can be compensated for during charac-
terization of the application cell.
3) CSN and CSP traces should make Kelvin connections
to RSNS. The device measures current differentially
through the CSN and CSP pins. Any shared high-
current paths on these traces will affect current-
measurement gain accuracy. PCB resistance that
cannot be removed can be compensated for during
characterization of the application cell.
4) VBATT capacitor trace loop area should be minimized.
The device shares the VBATT pin for both voltage mea-
surement and IC power. Limiting noise at the VBATT
pin is important to current-measurement accuracy.
5) REG capacitor trace loop area should be minimized.
The helps filter any noise from the internal regulated
supply.
6) There are no limitations on any other IC connection.
Connections to THRM, ALRT, SDA, SCL, VTT, and
AIN, as well as any external components mounted to
these pins, have no special layout requirements.
MAX17047
VOLTAGE BASED
ON EXISTING
CHARGER REQUIREMENTS
VBIAS
VSYSTEM
VBATT
THERMISTOR
INSIDE
CELL PACK
MAX17047 + CHARGER
WITH EXTERNAL BIAS
PK-PK-
CHARGER WITH
VTT + THRM
AVAILABLE
VTT
THRM
CSPAIN
MAX17047
VBIAS
2.8V < VBIAS < VINTERNAL + 0.6V
VSYSTEM
VBATT
THERMISTOR
INSIDE
CELL PACK
MAX17047 + CHARGER
WITH INTERNAL BIAS
CHARGER WITH
INTERNAL
BIAS
VTT
THRM
CSPAIN
VINTERNAL
ON DURING
CHARGE
OFF DURING
DISCHARGE
MAX17047/MAX17050
ModelGauge m3 Fuel Gauge
ModelGauge m3 Registers
To calculate accurate results, ModelGauge m3 requires
information about the cell, the application, and real-time
information measured by the device. Figure 9 shows all
inputs and outputs to the algorithm grouped by category.
Analog input registers are the real-time measurements
of voltage, temperature, and current performed by the
device. Application-specific registers are programmed
by the customer to reflect the operation of the applica-
tion. The Cell Characterization Information registers
hold characterization data that models the behavior of
the cell over the operating range of the application. The
Algorithm Configuration registers allow the host to adjust
performance of the device for its application. The Save
and Restore registers allow an application to maintain
accuracy of the algorithm after the device has been
power cycled. The following sections describe each
register in detail.
ModelGauge Algorithm
Output Registers
The following registers hold the output results from the
ModelGauge m3 algorithm.
SOCMIX Register (0Dh)
The SOCMIX register holds the calculated present state
of charge of the cell before any empty compensation
adjustments are performed. The register value is stored
as a percentage with a resolution of 0.0039% per LSb.
If an 8-bit state-of-charge value is desired, the host can
discard the lower byte and use only the upper byte of the
register with a resolution of 1.0%. Figure 10 shows the
SOCMIX register format.
Figure 8. Proper Board Layout
MAX17050
POSITIVE
POWER BUS
POSITIVE
POWER BUS
NEGATIVE
POWER BUS
NEGATIVE
POWER BUS
SDAVBATTAIN
THRMALRTSCL
CSPREGCSN
PACK+PACK+
VBATT
VTT
AIN
SCL
SDA
CSN
THRM
ALRT
REGREG
CSP
CREG
RSNSRSNS
CVBATTCVBATT
PACK-PACK-
CREG
MAX17047
MAX17047/MAX17050
ModelGauge m3 Fuel Gauge
Figure 9. ModelGauge m3 Register Map
Figure 10. SOCMIX Register Format (Output)
ModelGauge ALGORITHMVCELL
CURRENT
TEMPERATURE
AverageVCELL
AverageCurrent
AverageTemperature
FilterCFG
LearnCFG
RelaxCFG
MiscCFG
AtRate
ALGORITHM
CONFIGURATION
FullCapNom
Iavg_empty
CELL
CHARACTERIZATION
INFORMATION
RCOMP0
TempCo
TempNom
TempLim
V_empty
CHARACTERIZATION
TABLE
FCTC
QResidual Table
ANALOG
INPUTS
DesignCap
ICHGTerm
FullSOCThr
V_empty
APPLICATION
SPECIFIC
FullCAP
FullCapNom
FSTAT
RemCapMIX
SOCREP
RemCapREP
SOCAV
RemCapAV
TTE
AGE
CYCLES
OCV
SOCMIX
ModelGauge
ALGORITHM
OUTPUTS
CYCLES
RCOMP0
TempCo
dQacc
dPacc
FullCAP
SAVE AND
RESTORE
INFORMATION
QResidual Table
MSB—ADDRESS 0DhLSB—ADDRESS 0Dh262524232221202-12-22-32-42-52-62-72-8
MSbLSbMSbLSb
2-8 UNITS: 0.0039%
20 UNITS: 1.0%
MAX17047/MAX17050
ModelGauge m3 Fuel Gauge
RemCapMIX Register (0Fh)
The RemCapMIX register holds the calculated remain-
ing capacity of the cell before any empty compensation
adjustments are performed. The value is stored in terms
of FVh and must be divided by the application sense-
resistor value to determine remaining capacity in mAh.
Figure 11 shows the RemCapMIX register format.
SOCREP Register (06h)
SOCREP is a filtered version of the SOCAV register that
prevents large jumps in the reported value caused by
changes in the application such as abrupt changes in
load current. The register value is stored as a percent-
age with a resolution of 0.0039% per LSb. If an 8-bit SOC
value is desired, the host can discard the lower byte and
use only the upper byte of the register with a resolution
of 1.0%. Figure 12 shows the SOCREP register format.
RemCapREP Register (05h)
RemCapREP is a filtered version of the RemCapAV register
that prevents large jumps in the reported value caused by
changes in the application such as abrupt changes in load
current. The value is stored in terms of FVh and must be
divided by the application sense-resistor value to determine
remaining capacity in mAh. During application idle periods
where the AverageCurrent Register value is less than Q6
LSbs, RemCapREP does not change. The measured cur-
rent during this period is still accumulated into RemCapMIX
and is slowly reflected in RemCapREP once cell loading or
charging occurs. Figure 13 shows the RemCapREP register
format.
Figure 11. RemCapMIX Register Format (Output)
Figure 12. SOCREP Register Format (Output)
Figure 13. RemCapREP Register Format (Output)
MSB—ADDRESS 0FhLSB—ADDRESS 0Fh
MSbLSbMSbLSb
20 UNITS: 5.0FVh/RSENSE
(0.5mAh WHEN RSENSE = 0.010I)
MSB—ADDRESS 06hLSB—ADDRESS 06h262524232221202-12-22-32-42-52-62-72-8
MSbLSbMSbLSb
2-8 UNITS: 0.0039%
20 UNITS: 1.0%
MSB—ADDRESS 05hLSB—ADDRESS 05h
MSbLSbMSbLSb
20 UNITS: 5.0FVh/RSENSE
(0.5mAh WHEN RSENSE = 0.010I)
MAX17047/MAX17050
ModelGauge m3 Fuel Gauge
SOCAV Register (0Eh)
The SOCAV register holds the calculated present state
of charge of the cell based on all inputs from the
ModelGauge m3 algorithm including empty compensa-
tion. The register value is stored as a percentage with a
resolution of 0.0039% per LSb. If an 8-bit state-of-charge
value is desired, the host can discard the lower byte and
use only the upper byte of the register with a resolution of
1.0%. The SOCAV register value is an unfiltered calcula-
tion. Jumps in the value can be caused by changes in
the application such as abrupt changes in load current.
Figure 14 shows the SOCAV register format.
RemCapAV Register (1Fh)
The RemCapAV register holds the calculated remain-
ing capacity of the cell based on all inputs from the
ModelGauge m3 algorithm including empty compen-
sation. The value is stored in terms of FVh and must
be divided by the application sense-resistor value to
determine the remaining capacity in mAh. The register
value is an unfiltered calculation. Jumps in the value can
be caused by changes in the application such as abrupt
changes in load current. Figure 15 shows the RemCapAV
register format.
SOCVF Register (FFh)
The SOCVF register holds the calculated present SOC of
the battery according to the voltage fuel gauge. The reg-
ister value is stored as a percentage with a resolution of
0.0039% per LSb. If an 8-bit SOC value is desired, the host
can discard the lower byte and use only the upper byte of
the register with a resolution of 1.0%. Figure 16 shows the
SOCVF register format.
TTE Register (11h)
The TTE register holds the estimated time to empty for
the application under present conditions. The TTE value
is determined by dividing the RemCapAV register by the
AverageCurrent register. The result is stored in the TTE
register with a resolution of 5.625s per LSb.
Figure 14. SOCAV Register Format (Output)
Figure 15. RemCapAV Register Format (Output)
MSB—ADDRESS 0EhLSB—ADDRESS 0Eh262524232221202-12-22-32-42-52-62-72-8
MSbLSbMSbLSb
2-8 UNITS: 0.0039%
20 UNITS: 1.0%
MSB—ADDRESS 1FhLSB—ADDRESS 1Fh
MSbLSbMSbLSb
20 UNITS: 5.0FVh/RSENSE
(0.5mAh WHEN RSENSE = 0.010I)
MSB—ADDRESS FFhLSB—ADDRESS FFh262524232221202-12-22-32-42-52-62-72-8
MSbLSbMSbLSb
2-8 UNITS: 0.0039%
20 UNITS: 1.0%
MAX17047/MAX17050
ModelGauge m3 Fuel Gauge
Figure 17. TTE Register Format (Output)
Figure 18. Age Register Format (Output)
Alternatively, the TTE register can be used to estimate time
to empty for any given current load. Whenever the AtRate
register is programmed to a negative number, representing
a discharge current, the TTE register displays the estimated
time to empty for the application based on the AtRate regis-
ter value. Figure 17 shows the TTE register format.
Age Register (07h)
The Age register contains a calculated percentage value
of the application’s present cell capacity compared to its
expected capacity. The result can be used by the host to
gauge the cell’s health as compared to a new cell of the
same type. The result is displayed as a percentage value
from 0 to 256% with a 0.0039% LSb. Figure 18 shows the
Age register format. The equation for the register output is:
Age Register = 100% O (FullCAP Register/
DesignCap Register)
Cycles Register (17h)
The Cycles register accumulates total percent change in
the cell during both charging and discharging. The result
is stored as a total count of full charge/discharge cycles.
For example, a full charge/discharge cycle results in
the Cycles register incrementing by 100%. The Cycles
register has a full range of 0 to 65535% with a 1% LSb.
This register is reset to 0% at power-up. To maintain the
lifetime cycle count of the cell, this register must be peri-
odically saved by the host and rewritten to the device at
power-up. See the Save and Restore Registers section
for details. See Figure 19 for the Cycles register format.
VFOCV Register (FBh)
The VFOCV register contains the raw open-circuit volt-
age output of the voltage fuel gauge. This value is used
in other internal calculations and can be read for debug
purposes. The result is a 12-bit value ranging from 2.5V
to 5.119V where 1 LSb is 1.25mV. The bottom 4 bits of
this register are don’t care bits. See Figure 20 for the
VFOCV register format.
MSB—ADDRESS 11hLSB—ADDRESS 11h
MSbLSbMSbLSb
20 UNITS: 3.0min
MSB—ADDRESS 07hLSB—ADDRESS 07h262524232221202-12-22-32-42-52-62-72-8
MSbLSbMSbLSb
20 UNITS: 1.0%
2-8 UNITS: 0.0039%
MSB—ADDRESS 17hLSB—ADDRESS 17h
MSbLSbMSbLSb
20 UNITS: 1.0%
MAX17047/MAX17050
ModelGauge m3 Fuel Gauge
FullCAP Register (10h)
This register holds the ModelGauge m3 algorithm calcu-
lated full capacity of the cell under best-case conditions
(light load, hot). A new full-capacity value is calculated
after the end of every charge cycle in the application. The
value is stored in terms of FVh and must be divided by
the application sense-resistor value to determine capac-
ity in mAh. Figure 21 is the FullCAP register format. See
the End-of-Charge Detection section.
FullCapNom Register (23h)
This register holds the calculated full capacity of the cell,
not including temperature and charger tolerance. New
full capacity values are calculated periodically by the IC
during operation. The value is stored in terms of FVh and
must be divided by the application sense resistor value
to determine capacity in mAh. This register is used to
calculate the outputs of the ModelGauge m3 algorithm
and is available to the user only for debug. Figure 22 is
the FullCapNom register format.
Figure 20. VFOCV Register Format (Output)
Figure 21. FullCAP Register Format (Output)
Figure 22. FullCapNom Register Format (Output)
MSB—ADDRESS FBhLSB—ADDRESS FBh
21121029282726252423222120XXXX
MSbLSbMSbLSb
20 UNITS: 1.25mV
X = DON’T CARE
MSB—ADDRESS 10hLSB—ADDRESS 10h
MSbLSbMSbLSb
20 UNITS: 5.0FVh/RSENSE
(0.5mAh WHEN RSENSE = 0.010I)
MSB—ADDRESS 23hLSB—ADDRESS 23h
MSbLSbMSbLSb
20 UNITS: 5.0FVh/RSENSE
(0.5mAh WHEN RSENSE = 0.010I)
MAX17047/MAX17050
ModelGauge m3 Fuel Gauge
QH Register (4Dh)
The QH register displays the raw coulomb count gener-
ated by the device. This register is used internally as an
input to the mixing algorithm. Monitoring changes in QH
over time can be useful for debugging device operation.
The QH register is set to 0000h at power-up. The QH reg-
ister format is shown in Figure 23.
Application-Specific Registers
The following registers define the behavior of the applica-
tion. They must be programmed by the user before the
ModelGauge m3 algorithm is accurate. Any changes to
these register values require recharacterization of the cell.
DesignCap Register (18h)
The DesignCap register holds the expected capacity of
the cell. This value is used to determine age and health
of the cell by comparing against the calculated pres-
ent capacity stored in the FullCAP register. DesignCap
has an LSb equal to 5.0FVh and a full range of 0 to
327.68mVh. The user should multiply the mAh capac-
ity of the cell by the sense resistor value to determine
the FVh value to store in the DesignCap register. The
DesignCap register format is shown in Figure 24.
FullSOCThr Register (13h)
The FullSOCThr register gates detection of end-of-
charge. SOCVF must be larger than the FullSOCThr
value before ICHGTerm is compared to the
AverageCurrent register value. The recommended
FullSOCThr register setting for most applications is 95%.
See the ICHGTerm register description for details. The
FullSOCThr register is 70% at power-up. Figure 25 is the
FullSOCThr register format.
Figure 23. QH Register Format (Output)
Figure 24. DesignCap Register Format (Input)
Figure 25. FullSOCThr Register Format (Input)
MSB—ADDRESS 23hLSB—ADDRESS 23h
MSbLSbMSbLSb
20 UNITS: 5.0FVh/RSENSE
(0.5mAh WHEN RSENSE = 0.010I)
MSB—Address 4DhLSB—ADDRESS 4Dh
MSbLSbMSbLSb
20 UNITS: 5.0FVh/RSENSE
(0.5mAh WHEN RSENSE = 0.010I)
MSB—ADDRESS 18hLSB—ADDRESS 18h262524232221202-12-22-32-42-52-62-72-8
MSbLSbMSbLSb
2-8 UNITS: 0.0039%
20 UNITS: 1.0%
MAX17047/MAX17050
ModelGauge m3 Fuel Gauge
End-of-Charge Detection
The device detects the end of a charge cycle when
the application current falls into the band set by the
ICHGTerm register value. By monitoring both the Current
and AverageCurrent registers, the device can reject false
end-of-charge events such as application load spikes
or early charge-source removal. See the End-of-Charge
Detection graph in the Typical Operating Characteristics
and Figure 26.
Figure 26. False End-of-Charge Events
AVERAGE CURRENT
CURRENT
0mA
AVERAGE CURRENT
CURRENT
1.25 x ICHGTerm
0.125 x ICHGTerm
1.25 x ICHGTerm
0.125 x ICHGTerm
0mA
CHARGING
CHARGING
DISCHARGING
DISCHARGING
HIGH-CURRENT LOAD SPIKES DO NOT GENERATE END-OF-CHARGE
DETECTION BECAUSE CURRENT AND AVERAGE CURRENT READINGS
DO NOT FALL INTO THE DETECTION AREA AT THE SAME TIME.
EARLY CHARGER REMOVAL DOES NOT GENERATE END-OF-CHARGE
DETECTION BECAUSE CURRENT AND AVERAGE CURRENT READINGS
DO NOT FALL INTO THE DETECTION AREA AT THE SAME TIME.
MAX17047/MAX17050
ModelGauge m3 Fuel Gauge
When a proper end-of-charge event is detected, the
device learns a new FullCAP register value based on
the RemCapREP output. If the old FullCAP value was too
high, it is adjusted downward after the last valid end-
of-charge detection. If the old FullCAP was too low, it is
adjusted upward to match RemCapREP. This prevents
the calculated state of charge from ever reporting a value
greater than 100%. See Figure 27.
ICHGTerm Register (1Eh)
The ICHGTerm register allows the device to detect when
a charge cycle of the cell has completed. The host
should set the ICHGTerm register value equal to the
exact charge termination current used in the application.
The device detects end of charge if all the following con-
ditions are met:
SOCVF > FullSOCThrAND ICHGTerm x 0.125 < Current < ICHGTerm x 1.25AND ICHGTerm x 0.125 < AverageCurrent <
ICHGTerm x 1.25
Values are stored in FV. Multiply the termination current
by the sense resistor to determine the desired register
value. This register has the same range and resolution
as the Current register. Figure 28 shows the ICHGTerm
register format. ICHGTerm defaults to 150mA (03C0h) at
power-up.
Figure 27. FullCAP Learning at End of Charge
AVERAGE CURRENT
CURRENT
0mA
AVERAGE CURRENT
CURRENT
1.25 x ICHGTerm
0.125 x ICHGTerm
1.25 x ICHGTerm
0.125 x ICHGTerm
0mA
CHARGING
CHARGING
DISCHARGING
DISCHARGING
HIGH-CURRENT LOAD SPIKES DO NOT GENERATE END-OF-CHARGE
DETECTION BECAUSE CURRENT AND AVERAGE CURRENT READINGS
DO NOT FALL INTO THE DETECTION AREA AT THE SAME TIME.
EARLY CHARGER REMOVAL DOES NOT GENERATE END-OF-CHARGE
DETECTION BECAUSE CURRENT AND AVERAGE CURRENT READINGS
DO NOT FALL INTO THE DETECTION AREA AT THE SAME TIME.
MAX17047/MAX17050
ModelGauge m3 Fuel Gauge
V_empty Register (3Ah)
The V_empty register sets thresholds related to empty
detection during operation. Figure 29 is the V_empty
register format.
VE8:VE0—Empty Voltage. Sets the voltage level for
detecting empty. A 10mV resolution gives a 0 to 5.11V
range. This value is written to 3.12V at power-up.
VR6:VR0—Recovery Voltage. Sets the voltage level for
clearing empty detection. Once the cell voltage rises
above this point, empty voltage detection is reenabled.
A 40mV resolution gives a 0 to 5.08V range. This value is
written to 3.68V at power-up.
Cell Characterization
Information Registers
Proper cell characterization is required to achieve accu-
racy. The following registers (Table 1) hold information
that must be generated through a cell-characterization
procedure. Maxim provides a cell-characterization ser-
vice. Contact the factory for details.
Figure 28. ICHGTerm Register Format (Input)
Figure 29. V_empty Register Format (Input)
Table 1. Cell Characterization Information
Registers
REGISTERADDRESS
Characterization Table (48 words)80h to AFh
FullCap10h
DesignCap18h
ICHGTerm1Eh
FullCapNom23h
RCOMP038h
lavg_empty36h
TempCo39h
QResidual 0012h
QResidual 1022h
QResidual 2032h
QResidual 3042h
MSB—ADDRESS 1EhLSB—ADDRESS 1Eh21421321221121029282726252423222120
MSbLSbMSbLSb
UNITS: 1.5625FV/RSENSE
MSB—ADDRESS 3AhLSB—ADDRESS 3Ah
VE8VE8VE6VE5VE4VE3VE2VE1VE0VR6VR5VR4VR3VR2VR1VR0
MSbLSbMSbLSb
VR0 UNITS: 40mV
VE0 UNITS: 10mV
MAX17047/MAX17050
ModelGauge m3 Fuel Gauge
Algorithm Configuration Registers
The following registers allow operation of the ModelGauge
m3 algorithm to be adjusted for the application. It is recom-
mended that the default values for these registers be used.
FilterCFG Register (29h)
The FilterCFG register sets the averaging time period for
all A/D readings, for mixing OCV results and coulomb-
count results. It is recommended that these values are
not changed unless absolutely required by the applica-
tion. Figure 30 shows the FilterCFG register format:
CURR3:CURR0—Sets the time constant for the
AverageCurrent register. The default POR value of 4h gives
a time constant of 11.25 seconds. The equation setting the
period is:
AverageCurrent time constant = 175.8ms O 2(2+CURR)
VOLT2:VOLT0—Sets the time constant for the
AverageVCELL register. The default POR value of 2h gives
a time constant of 45.0s. The equation setting the period is:
AverageVCELL time constant = 175.8ms O 2(6+VOLT)
MIX3:MIX0—Sets the time constant for the mixing algo-
rithm. The default POR value of Dh gives a time constant
of 12.8 hours. The equation setting the period is:
Mixing Period = 175.8ms O 2(5+MIX)
TEMP2:TEMP0—Sets the time constant for the
AverageTemperature register. The default POR value of
1h gives a time constant of 12min. The equation setting
the period is:
AvergeTemperature time constant = 175.8ms x 2(8 + TEMP)
X—Reserved. Do not modify.
RelaxCFG Register (2Ah)
The RelaxCFG register defines how the device detects
if the cell is in a relaxed state. See Figure 32. For a cell
to be considered relaxed, current flow through the cell
must be kept at a minimum while the change in the cell’s
voltage over time, dV/dt, shows little or no change. If
AverageCurrent remains below the Load threshold while
VCELL changes less than the dV threshold over two
consecutive periods of dt, the cell is considered relaxed.
Figure 31 shows the RelaxCFG register format:
Load6:Load0—Sets the threshold, which the
AverageCurrent register is compared against. The
AverageCurrent register must remain below this thresh-
old value for the cell to be considered unloaded. Load is
an unsigned 7-bit value where 1 LSb = 50FV. The default
value is 800FV.
Figure 31. RelaxCFG Register Format (Input)
Figure 30. FilterCFG Register Format (Input)
MSB—ADDRESS 2AhLSB—ADDRESS 2Ah
Load6Load5Load4Load3Load2Load1Load0dV4dV3dV2dV1dV0dt3dt2dt1dt0
MSbLSbMSbLSb
LOAD0 UNITS: 50FV/RSENSE
(5.0mAh WHEN RSENSE = 0.010I)
MSB—ADDRESS 29hLSB—ADDRESS 29hXTEMP
TEMP
TEMP MIX3MIX2MIX1MIX0VOLT2VOLT1VOLT0CURR
CURR
CURR
CURR
MSbLSbMSbLSb
