MAX17043G+T Maxim Integrated Products, MAX17043G+T Datasheet - Page 6

• Manufacturer Part Number: MAX17043G+T
• Description: IC 2-WIRE FG MODEL GAUGE LO BATT
• Manufacturer: Maxim Integrated Products
• Series: ModelGauge™r

Specifications of MAX17043G+T

• Function: Fuel, Gas Gauge/Monitor
• Battery Type: Lithium-Ion (Li-Ion)
• Voltage - Supply: 2.5 V ~ 4.5 V
• Operating Temperature: -20°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 8-TDFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 90-2771G+BTR

Compact, Low-Cost 1S/2S Fuel Gauges
with Low-Battery Alert
Figure 1. 2-Wire Bus Timing Diagram
Figure 1 shows the 2-wire bus timing diagram, and
Figure 2 is the MAX17043/MAX17044 block diagram.
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 considers 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
Figure 2. Block Diagram
6
CELL
ModelGauge Theory of Operation
GND
V
_______________________________________________________________________________________
SDA
SCL
DD
t
F
S
ADC (V
REFERENCE
VOLTAGE
BIAS
CELL
GROUND
t
LOW
t
HD:STA
)
IC
Detailed Description
MAX17043
MAX17044
t
R
t
HD:DAT
(SOC, RATE)
INTERFACE
TIME BASE
MACHINE
t
(32kHz)
2-WIRE
SU:DAT
STATE
t
F
CTG
QSTRT
ALRT
SDA
SCL
t
SU:STA
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 variants across temperature
and age. The MAX17043/MAX17044 have a preloaded
ROM table that provides very good performance for
most chemistries.
The classical coulomb-counter-based fuel gauges suf-
fer 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 periodic corrections. The corrections are usu-
ally performed on a predefined SOC level near full or
empty. Some other systems use the relaxed battery
voltage to perform corrections. These systems deter-
mine 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 experienced 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.
Sr
t
HD:STA
Fuel-Gauge Performance
t
SU:STO
t
SP
t
R
P
t
BUF
S