Datasheet

MAX17043/MAX17044
Compact, Low-Cost 1S/2S Fuel Gauges
with Low-Battery Alert
8 _______________________________________________________________________________________
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 reso-
lutions 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 conver-
sion 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
automatically adapts to variation in battery size since
the MAX17043/MAX17044 naturally recognize relative
SOC. Units of % can be directly determined by observ-
ing 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 available to the actual application because
of early termination voltage requirements. When SOC()
= 0, typical applications have no remaining capacity.
The first update occurs 125ms after POR of the IC.
Subsequent updates occur at variable intervals
depending on application conditions. ModelGauge cal-
culations outside 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 opti-
mize IC performance for different lithium chemistries or
different operating temperatures. Contact Maxim for
instructions for optimization. The power-up default
value for CONFIG is 97h.
MSB—ADDRESS 02h LSB—ADDRESS 03h
2
11
2
10
2
9
2
8
2
7
2
6
2
5
2
4
2
3
2
2
2
1
2
0
0 0 0 0
MSB LSB MSB LSB
0: BITS ALWAYS READ LOGIC 0
UNITS: 1.25mV FOR MAX17043
2.50mV FOR MAX17044
Figure 3. VCELL Register Format
MSB—ADDRESS 04h LSB—ADDRESS 05h
2
7
2
6
2
5
2
4
2
3
2
2
2
1
2
0
2
-1
2
-2
2
-3
2
-4
2
-5
2
-6
2
-7
2
-8
MSB LSB MSB LSB
UNITS: 1.0%
Figure 4. SOC Register Format
VALUE COMMAND DESCRIPTION
4000h Quick-Start
See the Quick-Start
description section.
Table 2. MODE Register Commands