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MAX17047

ModelGauge m3 Fuel Gauge

�� Maxim Integrated Products 1

Simplified Operating Circuit

19-6008; Rev 0; 9/11

Ordering Information appears at end of data sheet.

For related parts and recommended products to use with this part,

refer to: www.maxim-ic.com/MAX17047.related

ModelGauge is a trademark of Maxim Integrated Products, Inc.

General Description

The MAX17047 incorporates 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 % 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,

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 (I

C) interface provides access to data and control

registers. The IC is available in a lead(Pb)-free, 3mm x

3mm, 10-pin TDFN package.

Applications

Features

S Accurate Battery-Capacity 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 (I

C) Interface

S Tiny, Lead(Pb)-Free, 3mm x 3mm, 10-Pin TDFN

Package

2.5G/3G/4G Wireless

Handsets

Smartphones/PDAs

Tablets and Handheld

Computers

Portable Game Players

e-Readers

Digital Still and Video

Cameras

Portable Medical Equipment

0.1µF0.1µF

OPTIONAL

10nF

OPTIONAL

10kI

PK-

PK+

OPTIONAL

10kI

NTC

THERMISTOR

10mI

RSNS

CSP

REG

AIN SCL

THRM

BATT

CSNEP

SDA

ALRT

MAX17047

PROTECTION

SYSTEM

BATTERY PACK

HOST

µP

For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,

or visit Maxim’s website at www.maxim-ic.com.

Summary of content (46 pages)

PAGE 1
9-6008; Rev 0; 9/11 MAX17047 ModelGauge m3 Fuel Gauge General Description The MAX17047 incorporates 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 industryleading fuel-gauge accuracy.
PAGE 2
MAX17047 ModelGauge m3 Fuel Gauge ABSOLUTE MAXIMUM RATINGS 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)....................
PAGE 3
MAX17047 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.
PAGE 4
MAX17047 ModelGauge m3 Fuel Gauge I2C Bus Timing Diagram SDA tF tLOW tR tSP tF tSU:DAT tR tBUF tHD:STA SCL tHD:STA tSU:STA tHD:DAT S tSU:STO P Sr S Figure 1. I2C Bus Timing Diagram Typical Operating Characteristics (TA = +25°C, unless otherwise noted.) 0.4 0.3 0.2 TA = -20°C 20 10 0 0 2 3 VBATT (V) 4 5 TA = -20°C 15 5 1 MAX17047 toc02 25 0.1 0 TA = +25°C 10 8 VOLTAGE ADC ERROR (mV) TA = +25°C 0.
PAGE 5
MAX17047 ModelGauge m3 Fuel Gauge Typical Operating Characteristics (continued) (TA = +25°C, unless otherwise noted.) AUXILIARY INPUT ADC ERROR vs. TEMPERATURE CURRENT ADC ERROR vs. TEMPERATURE TA = -20°C 5 0 -5 TA = +25°C MAX17047 toc05 0.80 AUXILIARY INPUT ADC ERROR (%) 10 TA = +70°C -10 0.60 0.40 TA = +70°C 0.20 0 TA = -20°C TA = +25°C -0.20 -0.40 -0.60 -0.80 -1.
PAGE 6
MAX17047 ModelGauge m3 Fuel Gauge Typical Operating Characteristics (continued) (TA = +25°C, unless otherwise noted.
PAGE 7
MAX17047 ModelGauge m3 Fuel Gauge Pin Configuration TOP VIEW VTT 1 AIN 2 SCL 3 SDA 4 CSN 5 + MAX17047 EP 10 VBATT 9 THRM 8 ALRT 7 REG 6 CSP TDFN Pin Description PIN NAME FUNCTION 1 VTT Supply Input for Thermistor Bias Switch. Connect to supply for ratiometric AIN pin-voltage measurements. In most applications, connect VTT to VBATT. 2 AIN Auxiliary Voltage Input. Auxiliary voltage input from external thermal-measurement network.
PAGE 8
MAX17047 ModelGauge m3 Fuel Gauge Block Diagram VBATT 0.1µF 32kHz OSCILLATOR ModelGauge m3 ALGORITHM 2V LDO PK- 0.
PAGE 9
MAX17047 ModelGauge m3 Fuel Gauge VOLTAGE FUEL GUAGE VOLTAGE RELAXED CELL DETECTION OCV TEMPERATURECOMPENSATION LEARN OCV CALCULATION OCV OUTPUT OCV TABLE LOOKUP % REMAINING OUTPUT COULOMB COUNTER mAh OUTPUT CURRENT TIME CAPACITY LEARN mAh PER % MIXING ALGORITHM mAh OUTPUT EMPTY DETECTION CURRENT TEMPERATURE RemCapMIX SOCMIX APPLICATION EMPTY COMPENSATION APPLICATION OUTPUTS: END-OF-CHARGE DETECTION SOCREP RemCapREP SOCAV RemCapAV TTE FullCAP CELL CHEMISTRY OUTPUTS: OCV CYCLES RCELL FullCAPNom
PAGE 10
MAX17047 ModelGauge m3 Fuel Gauge OCV Estimation and Coulomb-Count Mixing 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.
PAGE 11
MAX17047 ModelGauge m3 Fuel Gauge • Cell 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.
PAGE 12
MAX17047 ModelGauge m3 Fuel Gauge SYSTEM BATTERY PACK PK+ VBATT OPTIONAL 200kI VTT ALRT THRM THERMISTOR MEASUREMENT OPTIONAL OPTIONAL 10kI SDA MAX17047 AIN T OPTIONAL 5kI HOST µP SCL REG PROTECTION IC OPTIONAL 10kI NTC THERMISTOR OPTIONAL 10nF CSP 0.1µF EP CSN 0.1µF 10mI RSNS PK- Figure 5. Typical Operating Circuit VBIAS 2.8V < VBIAS < VINTERNAL + 0.
PAGE 13
MAX17047 ModelGauge m3 Fuel Gauge Recommended Layout Proper circuit layout (see Figure 7) is essential for measurement accuracy when using the MAX17047 ModelGauge m3 IC. The recommended layout guidelines are as follows: 1) Mount RSNS as close as possible to PACK-. The device shares both voltage and current measurements on the CSP pin. Therefore, it is important to limit the amount of trace resistance between the currentsensing resistor and PACK-. 2) VBATT trace should make a Kelvin connection to PACK+.
PAGE 14
MAX17047 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 8 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.
PAGE 15
MAX17047 ModelGauge m3 Fuel Gauge 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.
PAGE 16
MAX17047 ModelGauge m3 Fuel Gauge 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.
PAGE 17
MAX17047 ModelGauge m3 Fuel Gauge SOCVF Register (FFh) The SOCVF register holds the calculated present SOC of the battery according to the voltage fuel gauge. The register 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 15 shows the SOCVF register format.
PAGE 18
MAX17047 ModelGauge m3 Fuel Gauge 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.
PAGE 19
MAX17047 ModelGauge m3 Fuel Gauge 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.
PAGE 20
MAX17047 ModelGauge m3 Fuel Gauge FullSOCThr Register (13h) The FullSOCThr register gates detection of end-ofcharge. SOCVF must be larger than the FullSOCThr value before ICHGTerm is compared to the Average Current 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 24 is the FullSOCThr register format.
PAGE 21
MAX17047 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 26. AVERAGE CURRENT CURRENT CHARGING 1.25 x ICHGTerm 0.
PAGE 22
MAX17047 ModelGauge m3 Fuel Gauge ICHGTerm Register (1Eh) V_empty Register (3Ah) 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 conditions are met: The V_empty register sets thresholds related to empty detection during operation. Figure 28 is the V_empty register format.
PAGE 23
MAX17047 ModelGauge m3 Fuel Gauge Cell Characterization Information Registers Proper cell characterization is required to achieve accuracy. The following registers (Table 1) hold information that must be generated through a cell-characterization procedure. Maxim provides a cell-characterization service. Contact the factory for details. Algorithm Configuration Registers The following registers allow operation of the ModelGauge m3 algorithm to be adjusted for the application.
PAGE 24
MAX17047 ModelGauge m3 Fuel Gauge RelaxCFG Register (2Ah) an unsigned 7-bit value where 1 LSb = 50FV. The default value is 800FV. The RelaxCFG register defines how the device detects if the cell is in a relaxed state. See Figure 31. 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.
PAGE 25
MAX17047 ModelGauge m3 Fuel Gauge LearnCFG Register (28h) MiscCFG Register (2Bh) The LearnCFG register controls all functions relating to adaptation during operation. The LearnCFG register default values should not be changed unless specifically required by the application. Figure 32 is the LearnCFG register format: The MiscCFG control register enables various other functions of the device. The MiscCFG register default values should not be changed unless specifically required by the application.
PAGE 26
MAX17047 ModelGauge m3 Fuel Gauge MR4:MR0—Mixing Rate. This value sets the strength of the servo mixing rate after the final mixing state has been reached (> 2.08 complete cycles). The units are MR0 = 6.25FV, giving a range up to 19.375mA with a standard 0.010I sense resistor. Setting this value to 00000b disables servo mixing and the IC continues with timeconstant mixing indefinitely. The default setting is 25FV or 2.5mA with a standard sense resistor. enBi1—Enable reset on battery-insertion detection.
PAGE 27
MAX17047 ModelGauge m3 Fuel Gauge Power-Up and Power-On Reset Any power-on reset (POR) of the device resets all memory locations to their default POR value. This removes any custom cell characterization and application data, affects ALRT interrupt and shutdown mode settings, and resets all learned adjustments made by the fuel gauge.
PAGE 28
MAX17047 ModelGauge m3 Fuel Gauge Note that some registers are application outputs, some registers are for internal calculations, and some are characterization setup registers. Registers that are not internal are described in their own sections. These values should be stored by the application at periodic intervals.
PAGE 29
MAX17047 ModelGauge m3 Fuel Gauge CELL INSERTION FROM POWERED STATE (FTHRM = 0) VBATT UP TO 1.4s AIN 270ms A/D READINGS 175ms OUTPUT REGISTERS CELL INSERTION CELL INSERTION DETECTED A/D MEASUREMENTS COMPLETE SOC VALUES UPDATED CELL INSERTION FROM POWERED STATE (FTHRM = 1) VBATT UP TO 175ms AIN 270ms A/D READINGS 175ms OUTPUT REGISTERS CELL INSERTION CELL INSERTION DETECTED A/D MEASUREMENTS COMPLETE SOC VALUES UPDATED Figure 37.
PAGE 30
MAX17047 ModelGauge m3 Fuel Gauge Modes of Operation The device operates in one of two power modes: active and shutdown. While in active mode, the device operates as a high-precision battery monitor with temperature, voltage, auxiliary inputs, current, and accumulated current measurements acquired continuously, and the resulting values updated in the measurement registers. READ and WRITE access is allowed only in active mode.
PAGE 31
MAX17047 ModelGauge m3 Fuel Gauge ALRT Function The Alert Threshold registers allow interrupts to be generated by detecting a high or low voltage, a high or low temperature, or a high or low SOC. Interrupts are generated on the ALRT pin open-drain output driver. An external pullup is required to generate a logic-high signal. Note that if the pin is configured to be logic-low when inactive, the external pullup increases current drain.
PAGE 32
MAX17047 ModelGauge m3 Fuel Gauge SALRT Threshold Register (03h) The SALRT Threshold register (Figure 42) sets upper and lower limits that generate an ALRT pin interrupt if exceeded by the selected SOCREP, SOCAV, SOCMIX, or SOCVF register values. See the SACFG bits in the MiscCFG register description for details. The upper 8 bits set the maximum value and the lower 8 bits set the minimum value.
PAGE 33
MAX17047 ModelGauge m3 Fuel Gauge Note that if this bit is set to 1, the Bei, Ber, and Aen bits should be set to 0 to prevent an alert condition from causing the device to enter shutdown mode. I2CSH—I2C Shutdown. Set to logic 1 to force the device to enter shutdown mode if both SDA and SCL are held low for more than timeout of the SHDNTIMER register. This also configures the device to wake up on a rising edge of either SDA or SCL. Set to 1 at power-up.
PAGE 34
MAX17047 ModelGauge m3 Fuel Gauge THR2:THR0—Sets the shutdown timeout period from a minimum of 45s to a maximum of 1.6h. The default POR value of 7h gives a shutdown delay of 1.6h. The equation setting the period is: Shutdown Timeout Period = 175.8ms O 2(8+THR) Status Register (00h) The Status register maintains all flags related to alert thresholds and battery insertion or removal. Figure 46 shows the Status register format. POR—Power-On Reset.
PAGE 35
MAX17047 ModelGauge m3 Fuel Gauge Version Register (21h) above the maximum register value are reported as the maximum value. The lower 3 bits of the VCELL register are don’t care bits. Figure 48 shows the VCELL register format. Voltage Measurement The AverageVCELL register reports an average of VCELL register readings over a configurable 12s to 24min time period. See the FilterCFG register description for details on setting the time filter.
PAGE 36
MAX17047 ModelGauge m3 Fuel Gauge values. If VCELL is larger than the maximum or less than the minimum, the corresponding value is replaced with the new reading. At power-up, the MaxVCELL value is set to 00h (the minimum) and the MinVCELL value is set to FFh (the maximum). Therefore, both values are changed to the VCELL register reading after the first update. Host software can reset this register by writing it to its powerup value of 00FFh.
PAGE 37
MAX17047 ModelGauge m3 Fuel Gauge AverageCurrent Register (0Bh) The AverageCurrent register reports an average of current-register readings over a configurable 0.7s to 6.4h time period. See the FilterCFG register description for details on setting the time filter. The resulting average is placed in the AverageCurrent register with an LSb value of 1.5625FV/RSENSE. The first Current register reading after device power-up sets the starting point of the AverageCurrent filter.
PAGE 38
MAX17047 ModelGauge m3 Fuel Gauge For easiest software compatibility between systems, confiigure CGAIN to keep current LSB resolution at 0.15625mA. This preserves resolution of current readings and capacities. Both these registers are signed two’s complement. The default values of 4000h for CGAIN and 0000h for COFF preserve factory calibration and unit values (1.5625FV). Figure 54 shows the CGAIN register format and Figure 55 shows the COFF register format.
PAGE 39
MAX17047 ModelGauge m3 Fuel Gauge When Tex = 1 in the CONFIG register, the device does not update the Temperature register based on results from the AIN pin A/D. Instead, host software must periodically write the Temperature register with the known application temperature to keep the fuel gauge accurate. AIN Register (27h) While in active mode and Ten = 1 in the CONFIG register, the device periodically measures the voltage between pins AIN and CSP and compares the result to the voltage of the THRM pin.
PAGE 40
MAX17047 ModelGauge m3 Fuel Gauge the maximum or less than the minimum, the corresponding values are replaced with the new reading. At powerup, the MaxTemperature value is set to 80h (minimum) and the MinTemperature value is set to 7Fh (maximum). Therefore, both values are changed to the Temperature register reading after the first update. Host software can reset this register by writing it to its power-up value of 807Fh.
PAGE 41
MAX17047 ModelGauge m3 Fuel Gauge Figure 61 S MSB—ADDRESS 2Dh 26 26 25 24 23 LSB—ADDRESS 2Dh 22 MSb 21 20 LSb MSb 2-1 2-2 2-3 2-4 2-5 2-6 2-7 LSb 2-7 UNITS: +0.0078NC Figure 61. TOFF Register Format (Input) Table 5.
PAGE 42
MAX17047 ModelGauge m3 Fuel Gauge Table 5.
PAGE 43
MAX17047 ModelGauge m3 Fuel Gauge 2-Wire Bus System The 2-wire bus system supports operation as a slaveonly device in a single or multislave, and single or multimaster system. Up to 128 slave devices may share the bus by uniquely setting the 7-bit slave address. The 2-wire interface consists of a serial data line (SDA) and serial clock line (SCL). SDA and SCL provide bidirectional communication between the MAX17047 slave device and a master device at speeds up to 400kHz.
PAGE 44
MAX17047 ModelGauge m3 Fuel Gauge monitoring the acknowledge bit for presence of the device. More complex formats such as the write Data, read Data, and Function command protocols write data, read data, and execute device-specific operations, respectively. All bytes in each command format require the slave or the host system to return an Acknowledge bit before continuing with the next byte. Each function command definition outlines the required transaction format. Table 6 applies to the transaction formats.
PAGE 45
MAX17047 ModelGauge m3 Fuel Gauge Ordering Information PART TEMP RANGE PIN-PACKAGE MAX17047G+ -40°C to +85°C 10 TDFN-EP* MAX17047G+T10 -40°C to +85°C 10 TDFN-EP* +Denotes a lead(Pb)-free/RoHS-compliant package. T = Tape and reel. *EP = Exposed pad. Package Information For the latest package outline information and land patterns (footprints), go to www.maxim-ic.com/packages. Note that a “+”, “#”, or “-” in the package code indicates RoHS status only.
PAGE 46
MAX17047 ModelGauge m3 Fuel Gauge Revision History REVISION NUMBER REVISION DATE 0 9/11 DESCRIPTION Initial release PAGES CHANGED — Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits) shown in the Electrical Characteristics table are guaranteed.