General Description
The MAX17043/MAX17044 are ultra-compact, low-cost,
host-side fuel-gauge systems for lithium-ion (Li+) batter-
ies in handheld and portable equipment. The MAX17043
is configured to operate with a single lithium cell and the
MAX17044 is configured for a dual-cell 2S pack.
The MAX17043/MAX17044 use a sophisticated Li+ bat-
tery-modeling scheme, called ModelGauge™ to track
the battery’s relative state-of-charge (SOC) continuously
over a widely varying charge/discharge profile. Unlike
traditional fuel gauges, the ModelGauge algorithm elimi-
nates the need for battery relearn cycles and an external
current-sense resistor. Temperature compensation is pos-
sible in the application with minimal interaction between a
μC and the device.
The IC can be located on the system side, reducing cost
and supply chain constraints on the battery. Measurement
and estimated capacity data sets are accessed through
an I2C interface. The MAX17043/MAX17044 are avail-
able in either a 0.4mm pitch 9-bump UCSP™ or 2mm x
3mm, 8-pin TDFN lead-free package.
Applications
●Smartphones, Tablets
●Health and Fitness Monitors
●Digital Still, Video, and Action Cameras
●Medical Devices
●Handheld Computers and Terminals
●Wireless Speakers
Features
●Host-Side or Battery-Side Fuel Gauging
• 1 Cell (MAX17043)
• 2 Cell (MAX17044)
●Precision Voltage Measurement
• ±12.5mV Accuracy to 5.00V (MAX17043)
• ±30mV Accuracy to 10.00V (MAX17044)
●Accurate Relative Capacity (RSOC) Calculated from
ModelGauge Algorithm
●No Offset Accumulation on Measurement
●No Full-to-Empty Battery Relearning Necessary
●No Sense Resistor Required
●External Alarm/Interrupt for Low-Battery Warning
●2-Wire Interface
●Low Power Consumption
●Tiny, Lead(Pb)-Free, 8-Pin, 2mm x 3mm TDFN
Package or Tiny 0.4mm Pitch 9-Bump UCSP Package
19-4811; Rev 7; 1/17
ModelGauge is a trademark of Maxim Integrated Products, Inc.
UCSP is a trademark of Maxim Integrated Products, Inc.
Visit www.maximintegrated.com/products/patents for product
patent marking information.
+Denotes a lead(Pb)-free/RoHS-compliant package.
T = Tape and reel.
*EP = Exposed pad.
PART TEMP RANGE PIN-PACKAGE
MAX17043G+U -20°C to +70°C 8 TDFN-EP*
MAX17043G+T -20°C to +70°C 8 TDFN-EP*
MAX17043X+ -20°C to +70°C 9 UCSP
MAX17043X+T10 -20°C to +70°C 9 UCSP
MAX17044G+U -20°C to +70°C 8 TDFN-EP*
MAX17044G+T -20°C to +70°C 8 TDFN-EP*
MAX17044X+ -20°C to +70°C 9 UCSP
MAX17044X+T10 -20°C to +70°C 9 UCSP
Li+
PROTECTION
CIRCUIT
MAX17043
MAX17044
CELL
1µF
1kΩ
10nF
150Ω
GND EP
CTG
SCL
SDA
QSTRT
VDD
ALRT
SYSTEM
µP
I2C BUS
MASTER
INTERRUPT
4.7kΩ
MAX17043/MAX17044 1-Cell/2-Cell Fuel Gauge with
ModelGauge and Low-Battery Alert
Simple Fuel-Gauge Circuit Diagram
Ordering Information
EVALUATION KIT AVAILABLE
Voltage on CTG Pin Relative to VGND....................-0.3V to +12V
Voltage on CELL Pin Relative to VGND..................-0.3V to +12V
Voltage on All Other Pins Relative to VGND..............-0.3V to +6V
Operating Temperature Range..............................-40°C to +85°C
Storage Temperature Range
(TA = 0°C to +70°C (Note 10)).......................-55°C to +125°C
Lead Temperature (TDFN soldering only, 10s) ...............+300°C
Soldering Temperature (reflow) .......................................+260°C
(2.5V ≤ VDD ≤ 4.5V, TA = -20°C to +70°C, unless otherwise noted.)
(2.5V ≤ VDD ≤ 4.5V, TA = -20°C to +70°C, unless otherwise noted. Contact Maxim for VDD greater than 4.5V.)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Supply Voltage VDD (Note 1) +2.5 +4.5 V
Data I/O Pins
SCL, SDA,
QSTRT,
ALRT
(Note 1) -0.3 +5.5 V
MAX17043 CELL Pin VCELL (Note 1) -0.3 +5.0 V
MAX17044 CELL Pin VCELL (Note 1) -0.3 +10.0 V
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Active Current IACTIVE 50 75 µA
Sleep-Mode Current (Note 2) ISLEEP
VDD = 2.0V 0.5 1.0 µA
1 3
Time-Base Accuracy tERR
VDD = 3.6V at +25°C -1 +1
%TA = 0°C to +70°C (Note 10) -2 +2
TA = -20°C to +70°C -3 +3
MAX17043 Voltage-
Measurement Error
VGERR
TA = +25°C, VIN = VDD -12.5 +12.5 mV
-30 +30
MAX17044 Voltage-
Measurement Error
TA = +25°C, 5.0V < VIN < 9.0V -30 +30 mV
5.0 < VIN < 9.0 -60 +60
CELL Pin Input Impedance RCELL 15 MΩ
Input Logic-High:
SCL, SDA, QSTRT VIH (Note 1) 1.4 V
Input Logic-Low:
SCL, SDA, QSTRT VIL (Note 1) 0.5 V
Output Logic-Low: SDA VOL IOL = 4mA (Note 1) 0.4 V
Output Logic-Low: ALRT VOL-ALRT IOL-ALRT = 2mA (Note 1) 0.4 V
Pulldown Current: SCL, SDA IPD VDD = 4.5V, VPIN = 0.4V 0.2 µA
Input Capacitance: SCL, SDA CBUS 50 pF
Bus Low Timeout tSLEEP (Note 3) 1.75 2.5 s
Mode Transition tTRAN (Note 4) 1 ms
MAX17043/MAX17044 1-Cell/2-Cell Fuel Gauge with
ModelGauge and Low-Battery Alert
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Absolute Maximum Ratings
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.
Electrical Characteristics Recommended DC Operating Conditions
DC Electrical Characteristics
(2.5V ≤ VDD ≤ 4.5V, TA = -20°C to +70°C, unless otherwise noted.)
Note 1: All voltages are referenced to GND.
Note 2: SDA, SCL = GND; QSTRT, ALRT idle.
Note 3: The MAX17043/MAX17044 enter Sleep mode 1.75s to 2.5s after (SCL < VIL) AND (SDA < VIL).
Note 4: Time to enter sleep after Sleep command is sent. Time to exit sleep on rising edge of SCL or SDA.
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 75ns for the SDA signal (referred to the VIHMIN 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.
Note 10: Applies to 8-pin TDFN-EP package type only.
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
SCL Clock Frequency fSCL (Note 5) 0 400 kHz
Bus Free Time Between a STOP
and START Condition tBUF 1.3 µs
Hold Time (Repeated)
START Condition tHD:STA (Note 5) 0.6 µs
Low Period of SCL Clock tLOW 1.3 µs
High Period of SCL Clock tHIGH 0.6 µs
Setup Time for a Repeated
START Condition tSU:STA 0.6 µs
Data Hold Time tHD:DAT (Notes 6, 7) 0 0.9 µs
Data Setup Time tSU:DAT (Note 6) 100 ns
Rise Time of Both SDA
and SCL Signals tR20 +
0.1CB300 ns
Fall Time of Both SDA
and SCL Signals tF20 +
0.1CB300 ns
Setup Time for STOP Condition tSU:STO 0.6 µs
Spike Pulse Widths Suppressed
by Input Filter tSP (Note 8) 0 50 ns
Capacitive Load for Each
Bus Line CB(Note 9) 400 pF
SCL, SDA Input Capacitance CBIN 60 pF
MAX17043/MAX17044 1-Cell/2-Cell Fuel Gauge with
ModelGauge and Low-Battery Alert
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Electrical Characteristics: 2-Wire Interface
* Sample accuracy with custom configuration data programmed into the IC.
QUIESCENT CURRENT
vs. SUPPLY VOLTAGE
MAX17043/4 toc01
VDD (V)
QUIESCENT CURRENT (µA)
32 4 51
20
40
60
80
100
0
0
TA = +70°C
TA = +25°C
TA = -20°C
SIMPLE C/4 RATE CYCLES*
SOC ACCURACY
MAX17043/4 toc03
TIME (hr)
STATE OF CHARGE (%)
SOC ERROR (%)
12106 8 1816 22201442
10
20
30
40
50
60
70
80
90
100
0
-8
-6
-4
-2
0
2
4
6
8
10
-10
0
ERROR (%)
MAX17043/
MAX17044 SOC:
DASHED LINE
REFERENCE SOC:
SOLID LINE
C/2 RATE ZIGZAG PATTERN*
SOC ACCURACY
MAX17043/4 toc05
TIME (hr)
STATE OF CHARGE (%)
SOC ERROR (%)
128 16 22204
10
20
30
40
50
60
70
80
90
100
0
-8
-6
-4
-2
0
2
4
6
8
10
-10
0
ERROR (%)
MAX17043/MAX17044 SOC:
DASHED LINE
REFERENCE SOC:
SOLID LINE
SIMPLE C/2 RATE CYCLES*
SOC ACCURACY
MAX17043/4 toc02
TIME (h)
STATE OF CHARGE (%)
SOC ERROR (%)
12106 842
10
20
30
40
50
60
70
80
90
100
0
-8
-6
-4
-2
0
2
4
6
8
10
-10
0
ERROR (%)
MAX17043/
MAX17044 SOC:
DASHED LINE
REFERENCE SOC:
SOLID LINE
MAX17043 VOLTAGE ADC ERROR
vs. TEMPERATURE
MAX17043/4 toc04
TEMPERATURE (°C)
VOLTAGE ADC ERROR (mV)
3510 60 85-15
-15
-10
-5
0
5
10
15
20
-20
-40
VCELL = 3.0V
VCELL = 4.2V
VCELL = 3.6V
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MAX17043/MAX17044 1-Cell/2-Cell Fuel Gauge with
ModelGauge and Low-Battery Alert
PIN NAME FUNCTION
UCSP TDFN
A1 8 SDA Serial Data Input/Output. Open-drain 2-wire data line. Connect this pin to the DATA signal of the
2-wire interface. This pin has a 0.2µA typical pulldown to sense disconnection.
A2 7 SCL Serial Clock Input. Input only 2-wire clock line. Connect this pin to the CLOCK signal of the 2-wire
interface. This pin has a 0.2µA typical pulldown to sense disconnection.
A3 1 CTG Connect to Ground. Connect to VSS during normal operation.
B1 6 QSTRT Quick-Start Input. Allows reset of the device through hardware. Connect to GND if not used.
B2 N.C. No connect. Do not connect.
B3 2 CELL Battery Voltage Input. The voltage of the cell pack is measured through this pin.
C1 5 ALRT Alert Output. Active-low interrupt signaling low state of charge. Connect to interrupt input of the
system microprocessor.
C2 3 VDD Power-Supply Input. 2.5V to 4.5V input range. Connect to system power through a decoupling
network. Connect a 10nF typical decoupling capacitor close to pin.
C3 4 GND Ground. Connect to the negative power rail of the system.
— — EP Exposed Pad (TDFN only). Connect to ground.
TOP VIEW
(BUMPS ON BOTTOM)
SDA SCL CTG
QSTRT N.C. CELL
ALRT VDD GND
+
UCSP
1 2 3
B
C
A
MAX17043
MAX17044
1
+
3 4
8 6 5
SDA
QSTRT ALRT
2
7
SCL
CTG VDD GNDCELL
TDFN
(2mm x 3mm)
TOP VIEW
MAX17043
MAX17044
MAX17043/MAX17044 1-Cell/2-Cell Fuel Gauge with
ModelGauge and Low-Battery Alert
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Pin Description
Pin Congurations
Detailed Description
Figure 1 shows the 2-wire bus timing diagram, and
Figure 2 is the MAX17043/MAX17044 block diagram.
ModelGauge Theory of Operation
The MAX17043/MAX17044 use a sophisticated battery
model that determines the SOC of a nonlinear Li+ battery.
The model effectively simulates the internal dynamics of a
Li+ battery and determines the SOC. The model consid-
ers the time effects of a battery caused by the chemical
reactions and impedance in the battery. The MAX17043/
MAX17044 SOC calculation does not accumulate error
with time. This is advantageous compared to traditional
coulomb counters, which suffer from SOC drift caused by
current-sense offset and cell self-discharge. This model
provides good performance for many Li+ chemistry vari-
ants across temperature and age. To achieve optimum
performance, the MAX17043/MAX17044 must be pro-
grammed with configuration data custom to the applica-
tion. Contact the factory for details.
Fuel-Gauge Performance
The classical coulomb-counter-based fuel gauges suffer
from accuracy drift due to the accumulation of the offset
error in the current-sense measurement. Although the
error is often very small, the error increases over time in
such systems, cannot be eliminated, and requires peri-
odic corrections. The corrections are usually performed
on a predefined SOC level near full or empty. Some other
systems use the relaxed battery voltage to perform cor-
rections. These systems determine the true SOC based
on the battery voltage after a long time of no activity. Both
have the same limitation: if the correction condition is not
observed over time in the actual application, the error in
the system is boundless. In some systems, a full-charge/
discharge cycle is required to eliminate the drift error. 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. MAX17043/
MAX17044 do not suffer from the drift problem since they
do not rely on the current information.
Figure 2. Block Diagram
Figure 1. 2-Wire Bus Timing Diagram
STATE
MACHINE
(SOC, RATE)
2-WIRE
INTERFACE
IC
GROUND
TIME BASE
(32kHz)
ADC (VCELL)
VOLTAGE
REFERENCE
BIAS
GND
CELL
VDD
SCL
SDA
ALRT
QSTRT
CTG
MAX17043
MAX17044
SDA
SCL
tF
tLOW
tHD:STA
tHD:DAT
tSU:STA tSU:STO
tSU:DAT tHD:STA
tSP tRtBUF
tR
tF
S Sr PS
MAX17043/MAX17044 1-Cell/2-Cell Fuel Gauge with
ModelGauge and Low-Battery Alert
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IC Power-Up
When the battery is first inserted into the system, there is
no previous knowledge about the battery’s SOC. The IC
assumes that the battery has been in a relaxed state for
the previous 30min. The first A/D voltage measurement is
translated into a best “first guess” for the SOC. Initial error
caused by the battery not being in a relaxed state fades
over time, regardless of cell loading following this initial
conversion. Because the SOC determination is conver-
gent rather than divergent (as in a coulomb counter), this
initial error does not have a longlasting impact.
Quick-Start
A quick-start allows the MAX17043/MAX17044 to restart
fuel-gauge calculations in the same manner as initial pow-
er-up of the IC. For example, if an application’s power-up
sequence is exceedingly noisy such that excess error
is introduced into the IC’s “first guess” of SOC, the host
can issue a quick-start to reduce the error. A quick-start
is initiated by a rising edge on the QSTRT pin, or through
software by writing 4000h to the MODE register.
ALERT Interrupt
The MAX17043/MAX17044 have an interrupt feature that
alerts a host microprocessor whenever the cell’s state of
charge, as defined by the SOC register, falls below a pre-
defined alert threshold set at address 0Dh of the CONFIG
register.
When an alert is triggered, the IC drives the ALRT pin to
logic-low and sets the ALRT bit in the CONFIG register
to logic 1. The ALRT pin remains logic-low until the host
software writes the ALRT bit to logic 0 to clear the inter-
rupt. Clearing the ALRT bit while SOC is below the alert
threshold does not generate another interrupt. The SOC
register must first rise above and then fall below the alert
threshold value before another interrupt is generated.
Note that the alert function is not disabled at IC powerup.
If the first SOC calculation is below the threshold setting,
an interrupt is generated. Entering Sleep mode does not
clear the interrupt.
Sleep Mode
Holding both SDA and SCL logic-low forces the MAX17043/
MAX17044 into Sleep mode. While in Sleep mode, all IC
operations are halted and power drain of the IC is greatly
reduced. After exiting Sleep mode, fuel-gauge operation
continues from the point it was halted. SDA and SCL must
be held low for at least 2.5s to guarantee transition into
Sleep mode. Afterwards, a rising edge on either SDA or
SCL immediately transitions the IC out of Sleep mode.
Alternatively, Sleep mode can be entered by setting the
SLEEP bit in the CONFIG register to logic 1 through I2C
communication. If the SLEEP bit is set to logic 1, the only
way to exit Sleep mode is to write SLEEP to logic 0 or
power-on reset the IC.
Power-On Reset (POR)
Writing a value of 0054h to the COMMAND register
causes the MAX17043/MAX17044 to completely reset as
if power had been removed. The reset occurs when the
last bit has been clocked in. The IC does not respond with
an I2C ACK after this command sequence.
Registers
All host interaction with the MAX17043/MAX17044 is han-
dled by writing to and reading from register locations. The
MAX17043/MAX17044 have six 16-bit registers: SOC,
VCELL, MODE, VERSION, CONFIG, and COMMAND.
Register reads and writes are only valid if all 16 bits are
transferred. Any write command that is terminated early
is ignored. The function of each register is described
as follows. All remaining address locations not listed in
Table 1 are reserved. Data read from reserved locations
is undefined.
Table 1. Register Summary
ADDRESS
(HEX) REGISTER DESCRIPTION READ/
WRITE
DEFAULT
(HEX)
02h–03h VCELL Reports 12-bit A/D measurement of battery voltage. R —
04h–05h SOC Reports 16-bit SOC result calculated by ModelGauge algorithm. R —
06h–07h MODE Sends special commands to the IC. W —
08h–09h VERSION Returns IC version. R —
0Ch–0Dh CONFIG Battery compensation. Adjusts IC performance based on
application conditions. R/W 971Ch
FEh–FFh COMMAND Sends special commands to the IC. W —
MAX17043/MAX17044 1-Cell/2-Cell Fuel Gauge with
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VCELL Register
Battery voltage is measured at the CELL pin input
with respect to GND over a 0 to 5.00V range for the
MAX17043 and 0 to 10.00V for the MAX17044 with
resolutions of 1.25mV and 2.50mV, respectively. The A/D
calculates the average cell voltage for a period of 125ms
after IC POR and then for a period of 500ms for every
cycle afterwards. The VCELL register requires 500ms to
update after exiting Sleep mode. The result is placed in
the VCELL register at the end of each conversion period.
Figure 3 shows the VCELL register format.
SOC Register
The SOC register is a read-only register that displays
the state of charge of the cell as calculated by the
ModelGauge algorithm. The result is displayed as a
percentage of the cell’s full capacity. This register auto-
matically adapts to variation in battery size since the
MAX17043/MAX17044 naturally recognize relative SOC.
Units of % can be directly determined by observing only
the high byte of the SOC register. The low byte provides
additional resolution in units 1/256%. The reported SOC
also includes residual capacity, which might not be avail-
able to the actual application because of early termination
voltage requirements. When SOC() = 0, typical applica-
tions have no remaining capacity.
The first update occurs within 250ms after POR of the IC.
Subsequent updates occur at variable intervals depending
on application conditions. ModelGauge calculations out-
side the register are clamped at minimum and maximum
register limits. Figure 4 shows the SOC register format.
MODE Register
The MODE register allows the host processor to send
special commands to the IC (Table 2). Valid MODE reg-
ister write values are listed as follows. All other MODE
register values are reserved.
VERSION Register
The VERSION register is a read-only register that con-
tains a value indicating the production version of the
MAX17043/MAX17044.
CONFIG Register
The CONFIG register compensates the ModelGauge
algorithm, controls the alert interrupt feature, and forces
the IC into Sleep mode through software. The format of
CONFIG is shown in Figure 5.
CONFIG
CONFIG is an 8-bit value that can be adjusted to optimize
IC performance for different lithium chemistries or differ-
ent operating temperatures. Contact Maxim for instruc-
tions for optimization. The power-up default value for
CONFIG is 97h.
Figure 3. VCELL Register Format
Figure 4. SOC Register Format
Table 2. MODE Register Commands
VALUE COMMAND DESCRIPTION
4000h Quick-Start See the Quick-Start
description section.
MSB—ADDRESS 02h LSB—ADDRESS 03h
211 210 292827262524232221200 0 0 0
MSB LSB MSB LSB
0: BITS ALWAYS READ LOGIC 0 UNITS: 1.25mV FOR MAX17043
2.50mV FOR MAX17044
MSB—ADDRESS 04h LSB—ADDRESS 05h
27262524232221202-1 2-2 2-3 2-4 2-5 2-6 2-7 2-8
MSB LSB MSB LSB
UNITS: 1.0%
MAX17043/MAX17044 1-Cell/2-Cell Fuel Gauge with
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SLEEP (Sleep Bit)
Writing SLEEP to logic 1 forces the ICs into Sleep mode.
Writing SLEEP to logic 0 forces the ICs to exit Sleep
mode. The power-up default value for SLEEP is logic 0.
X (Don’t Care)
This bit reads as either a logic 0 or logic 1. This bit cannot
be written.
ALRT (ALERT Flag)
This bit is set by the IC when the SOC register value
falls below the alert threshold setting and an interrupt is
generated. This bit can only be cleared by software. The
power-up default value for ALRT is logic 0.
ATHD (Alert Threshold)
The alert threshold is a 5-bit value that sets the state of
charge level where an interrupt is generated on the ALRT
pin. The alert threshold has an LSb weight of 1% and can
be programmed from 1% up to 32%. The threshold value
is stored in two’s-complement form (00000 = 32%, 00001
= 31%, 00010 = 30%, 11111 = 1%). The power-up default
value for ATHD is 4% or 1Ch.
COMMAND Register
The COMMAND register allows the host processor to
send special commands to the IC. Valid COMMAND
register write values are listed as follows. All other
COMMAND register values are reserved. Table 3 shows
COMMAND register commands.
Application Examples
The MAX17043/MAX17044 have a variety of configura-
tions, depending on the application. Table 4 shows the
most common system configurations and the proper pin
connections for each.
Figure 5. CONFIG Register Format
Table 3. COMMAND Register Commands
Table 4. Possible Application Configurations
VALUE COMMAND DESCRIPTION
0054h POR See the Power-On Reset
(POR) section.
SYSTEM CONFIGURATION IC VDD ALRT QSTRT
1S Pack-Side Location MAX17043 Power directly from battery Leave unconnected Connect to GND
1S Host-Side Location MAX17043 Power directly from battery Leave unconnected Connect to GND
1S Host-Side Location,
Low Cell Interrupt MAX17043 Power directly from battery Connect to system
interrupt Connect to GND
1S Host-Side Location,
Hardware Quick-Start MAX17043 Power directly from battery Leave unconnected Connect to rising-edge
reset signal
2S Pack-Side Location MAX17044 Power from +2.5V to +4.5V
LDO in pack Leave unconnected Connect to GND
2S Host-Side Location MAX17044 Power from +2.5V to +4.5V
LDO or PMIC Leave unconnected Connect to GND
2S Host-Side Location,
Low Cell Interrupt MAX17044 Power from +2.5V to +4.5V
LDO or PMIC
Connect to system
interrupt Connect to GND
2S Host-Side Location,
Hardware Quick-Start MAX17044 Power from +2.5V to +4.5V
LDO or PMIC Leave unconnected Connect to rising-edge
reset signal
MSB—ADDRESS 0Ch LSB—ADDRESS 0Dh
RCOMP
27
RCOMP
26
RCOMP
25
RCOMP
24
RCOMP
23
RCOMP
22
RCOMP
21
RCOMP
20
SLEEP X ALRT ATHD
24
ATHD
23
ATHD
22
ATHD
21
ATHD
20
MSB LSB MSB LSB
ATHD UNITS: 1 LSB = 2’S COMPLEMENT 1%
ATHD RANGE: 11111b = 1%
00000b = 32%
MAX17043/MAX17044 1-Cell/2-Cell Fuel Gauge with
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Figure 6 shows an example application for a 1S cell pack.
The MAX17043 is mounted on the system side and pow-
ered directly from the cell pack. The external RC networks
on VDD and CELL provide noise filtering of the IC power
supply and A/D measurement. In this example, the ALRT
pin is connected to the microprocessor’s interrupt input
to allow the MAX17043 to signal when the battery is low.
The QSTRT pin is unused in this application, so it is tied
to GND.
Figure 7 shows a MAX17044 example application using
a 2S cell pack. The MAX17044 is mounted on the sys-
tem side and powered from a 3.3V supply generated
by the system. The CELL pin is still connected directly
to PACK+ through an external noise filter. The ALRT
pin is left unconnected because the interrupt feature is
not used in this application. After power is supplied, the
system watchdog generates a low-to-high transition on
the QSTRT pin to signal the MAX17044 to perform a
quick-start.
Figure 6. MAX17043 Application Example with Alert Interrupt
Figure 7. MAX17044 Application Example with Hardware Reset
PACK-
PACK+
PROTECTION IC
(Li+/POLYMER)
SYSTEM GND
SYSTEM VDD
BATTERY SYSTEM
MAX17043
CELL
EP
1µF
1kΩ
10nF
150Ω
GND
CTG
SCL
SDA
QSTRT
VDD
ALRT
SYSTEM µP
I2C BUS
MASTER
INTERRUPT
INPUT
4.7kΩ
PACK-
PACK+
PROTECTION IC
(Li+/POLYMER)
SYSTEM GND
SYSTEM VDD
BATTERY SYSTEM
MAX17044
CELL
1µF
1kΩ
GND
CTG SCL
SDA
QSTRT
VDD
SYSTEM PMIC
SYSTEM µP
I2C BUS
MASTER
3.3V OUTPUT
WATCHDOG
ALRT
EP
MAX17043/MAX17044 1-Cell/2-Cell Fuel Gauge with
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2-Wire Bus System
The 2-wire bus system supports operation as a slave-only
device in a single or multislave, and single or multimaster
system. Slave devices can share the bus by uniquely
setting the 7-bit slave address. The 2-wire interface
consists of a serial-data line (SDA) and serialclock line
(SCL). SDA and SCL provide bidirectional communication
between the MAX17043/MAX17044 slave device and a
master device at speeds up to 400kHz. The MAX17043/
MAX17044s’ SDA pin operates bidirectionally; that is,
when the MAX17043/MAX17044 receive data, SDA oper-
ates as an input, and when the MAX17043/MAX17044
return data, SDA operates as an open-drain output,
with the host system providing a resistive pullup. The
MAX17043/MAX17044 always operate as a slave device,
receiving and transmitting data under the control of a
master device. The master initiates all transactions on the
bus and generates the SCL signal, as well as the START
and STOP bits, which begin and end each transaction.
Bit Transfer
One data bit is transferred during each SCL clock cycle,
with the cycle defined by SCL transitioning low-to-high
and then high-to-low. The SDA logic level must remain
stable during the high period of the SCL clock pulse.
Any change in SDA when SCL is high is interpreted as a
START or STOP control signal.
Bus Idle
The bus is defined to be idle, or not busy, when no master
device has control. Both SDA and SCL remain high when
the bus is idle. The STOP condition is the proper method
to return the bus to the idle state.
START and STOP Conditions
The master initiates transactions with a START condition
(S) by forcing a high-to-low transition on SDA while SCL
is high. The master terminates a transaction with a STOP
condition (P), a low-to-high transition on SDA while SCL
is high. A Repeated START condition (Sr) can be used in
place of a STOP then START sequence to terminate one
transaction and begin another without returning the bus to
the idle state. In multimaster systems, a Repeated START
allows the master to retain control of the bus. The START
and STOP conditions are the only bus activities in which
the SDA transitions when SCL is high.
Acknowledge Bits
Each byte of a data transfer is acknowledged with an
acknowledge bit (A) or a no-acknowledge bit (N). Both
the master and the MAX17043 slave generate acknowl-
edge bits. To generate an acknowledge, the receiving
device must pull SDA low before the rising edge of the
acknowledge-related clock pulse (ninth pulse) and keep it
low until SCL returns low. To generate a no-acknowledge
(also called NAK), the receiver releases SDA before the
rising edge of the acknowledge-related clock pulse and
leaves SDA high until SCL returns low. Monitoring the
acknowledge bits allows for detection of unsuccessful
data transfers. An unsuccessful data transfer can occur
if a receiving device is busy or if a system fault has
occurred. In the event of an unsuccessful data transfer,
the bus master should reattempt communication.
Data Order
A byte of data consists of 8 bits ordered most significant
bit (MSb) first. The least significant bit (LSb) of each
byte is followed by the acknowledge bit. The MAX17043/
MAX17044 registers composed of multibyte values are
ordered MSb first. The MSb of multibyte registers is
stored on even data-memory addresses.
Slave Address
A bus master initiates communication with a slave device
by issuing a START condition followed by a slave address
(SAddr) and the read/write (R/W) bit. When the bus is
idle, the MAX17043/MAX17044 continuously monitor for
a START condition followed by its slave address. When
the MAX17043/MAX17044 receive a slave address that
matches the value in the slave address register, they
respond with an acknowledge bit during the clock period
following the R/W bit. The 7-bit slave address is fixed to
6Ch (write)/6Dh (read):
MAX17043/MAX17044
SLAVE ADDRESS 0110110
Read/Write Bit
The R/W bit following the slave address determines the
data direction of subsequent bytes in the transfer. R/W = 0
selects a write transaction, with the following bytes being
written by the master to the slave. R/W = 1 selects a read
transaction, with the following bytes being read from the
slave by the master. (Table 5).
MAX17043/MAX17044 1-Cell/2-Cell Fuel Gauge with
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Bus Timing
The MAX17043/MAX17044 are compatible with any bus
timing up to 400kHz. No special configuration is required
to operate at any speed.
2-Wire Command Protocols
The command protocols involve several transaction for-
mats. The simplest format consists of the master writing
the START bit, slave address, R/W bit, and then monitor-
ing the acknowledge bit for presence of the MAX17043/
MAX17044. More complex formats, such as the Write
Data and Read Data, read data and execute device-
specific operations. All bytes in each command format
require the slave or host to return an acknowledge bit
before continuing with the next byte. Table 5 shows the
key that applies to the transaction formats.
Basic Transaction Formats
Write: S. SAddr W. A. MAddr. A. Data0. A. Data1. A. P
A write transaction transfers 2 or more data bytes to the
MAX17043/MAX17044. The data transfer begins at the
memory address supplied in the MAddr byte. Control of
the SDA signal is retained by the master throughout the
transaction, except for the acknowledge cycles:
Read: S. SAddr W. A. MAddr. A. Sr. SAddr R. A. Data0. A. Data1. N. P
Write Portion Read Portion
A read transaction transfers 2 or more bytes from the
MAX17043/MAX17044. Read transactions are composed
of two parts, a write portion followed by a read portion,
and are therefore inherently longer than a write transac-
tion. The write portion communicates the starting point
for the read operation. The read portion follows immedi-
ately, beginning with a Repeated START, slave address
with R/W set to a 1. Control of SDA is assumed by the
MAX17043/MAX17044, beginning with the slave address
acknowledge cycle. Control of the SDA signal is retained
by the MAX17043/MAX17044 throughout the transaction,
except for the acknowledge cycles. The master indicates
the end of a read transaction by responding to the last
byte it requires with a no acknowledge. This signals the
MAX17043/MAX17044 that control of SDA is to remain
with the master following the acknowledge clock.
Write Data Protocol
The write data protocol is used to write to register to
the MAX17043/MAX17044 starting at memory address
MAddr. Data0 represents the data written to MAddr, Data1
represents the data written to MAddr + 1, and DataN
represents the last data byte, written to MAddr + N. The
master indicates the end of a write transaction by send-
ing a STOP or Repeated START after receiving the last
acknowledge bit:
SAddr W. A. MAddr. A. Data0. A. Data1. A... DataN. A.
The MSB of the data to be stored at address MAddr can
be written immediately after the MAddr byte is acknowl-
edged. Because the address is automatically incremented
after the LSB of each byte is received by the MAX17043/
MAX17044, the MSB of the data at address MAddr + 1
can be written immediately after the acknowledgment of
the data at address MAddr. If the bus master continues an
autoincremented write transaction beyond address 4Fh,
the MAX17043/MAX17044 ignore the data. A valid write
must include both register bytes. Data is also ignored
on writes to read-only addresses. Incomplete bytes and
bytes that are not acknowledged by the MAX17043/
MAX17044 are not written to memory.
Table 5. 2-Wire Protocol Key
KEY DESCRIPTION KEY DESCRIPTION
S START bit Sr Repeated START
SAddr Slave address (7 bit) W R/W bit = 0
MAddr Memory address byte P STOP bit
Data Data byte written by master Data Data byte returned by slave
A Acknowledge bit—master A Acknowledge bit—slave
N No acknowledge—master N No acknowledge—slave
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Read Data Protocol
The read data protocol is used to read to register from the
MAX17043/MAX17044 starting at the memory address
specified by MAddr. Both register bytes must be read
in the same transaction for the register data to be valid.
Data0 represents the data byte in memory location
MAddr, Data1 represents the data from MAddr + 1, and
DataN represents the last byte read by the master:
S. SAddr W. A. MAddr. A. Sr. SAddr R. A.
Data0. A. Data1. A... DataN. N. P
Data is returned beginning with the MSB of the data in
MAddr. Because the address is automatically increment-
ed after the LSB of each byte is returned, the MSB of the
data at address MAddr + 1 is available to the host imme-
diately after the acknowledgment of the data at address
MAddr. If the bus master continues to read beyond
address FFh, the MAX17043/MAX17044 output data val-
ues of FFh. Addresses labeled Reserved in the memory
map return undefined data. The bus master terminates
the read transaction at any byte boundary by issuing a no
acknowledge followed by a STOP or Repeated START.
PACKAGE TYPE PACKAGE CODE OUTLINE NO. LAND PATTERN NO.
8 TDFN T823+1 21-0174 90-0091
9 UCSP W91C1+1 21-0459 Refer to
Application Note 1891
MAX17043/MAX17044 1-Cell/2-Cell Fuel Gauge with
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Package Information
For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages. Note that a “+”,
“#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing
pertains to the package regardless of RoHS status.
REVISION
NUMBER
REVISION
DATE DESCRIPTION PAGES
CHANGED
0 9/09 Initial release —
1 4/10
Updated soldering temperature information; updated CTG pin voltage range to from 0.3V
to +12V to -0.3V to +12V in Absolute Maximum Ratings section; removed future asterisks
in ordering table; changed update time for SOC and VCELL; changed registers from
110ms/440ms to 125ms/500ms
1, 2, 8
2 9/10 Added description and ordering information for UCSP package type 1, 2, 3, 5,
13, 14
3 10/10 Updated Ordering Information table 1, 2, 13,14
4 8/11 Corrected time from start up until SOC valid; added text indicating accurate results require
custom conguration for each application 4, 6, 8, 14
5 6/12 Corrected soldering temperature in Absolute Maximum Ratings 2
6 8/12 Changed Soft POR command from 5400h to 0054h to avoid possible memory corruption 7, 9, 14
7 1/17 Updated front page title and applications 1
Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses
are implied. Maxim Integrated reserves the right to change the circuitry and specications without notice at any time. The parametric values (min and max limits)
shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc. © 2017 Maxim Integrated Products, Inc.
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14
MAX17043/MAX17044 1-Cell/2-Cell Fuel Gauge with
ModelGauge and Low-Battery Alert
Revision History
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