MAX17047/MAX17050
ModelGauge m3 Fuel Gauge
update. Host software can reset this register by writing it
to its power-up value of 807Fh. The maximum and mini-
mum voltages are each stored as two’s-complement 8-bit
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 descrip-
tion for details on setting the time filter. The resulting
average is placed in the AverageCurrent register with
values with 0.4mV/R
resolution. Figure 54 shows
SENSE
the MaxMinCurrent register format.
CGAIN Register (2Eh)/COFF Register (2Fh)
The CGAIN and COFF registers adjust the gain and off-
set of the current measurement result. The current mea-
surement A/D is factory trimmed to data-sheet accuracy
without the need for the user to make further adjustments.
The default power-up settings for CGAIN and COFF
apply no adjustments to the Current register reading. For
specific application requirements, the CGAIN and COFF
registers can be used to adjust readings as follows:
an LSb value of 1.5625FV/R
. The first Current
SENSE
register reading after device power-up sets the start-
ing point of the AverageCurrent filter. The last value
of the AverageCurrent register is maintained when the
device enters shutdown mode. Figure 53 shows the
AverageCurrent register format.
MaxMinCurrent Register (1Ch)
The MaxMinCurrent register maintains the maximum and
minimum Current register values since the last fuel gauge
reset or until cleared by host software. Each time the
Current register updates, it is compared against these
values. If the reading is larger than the maximum or less
than the minimum, the corresponding value is replaced
with the new reading. At power-up, the MaxCurrent value
is set to 80h (the minimum) and the MinCurrent value is
set to 7Fh (the maximum). Therefore, both values are
changed to the Current register reading after the first
Current Register = Current A/D Reading O
(CGAIN Register/16384) + (2 O COFF Register)
For easiest software compatibility between systems,
configure CGAIN to keep current LSb resolution at
0.15625mA. A minimum sense resistance of 0.005I
is required due to the maximum range of CGAIN. This
preserves resolution of current readings and capacities.
MSB—ADDRESS 0Ah
LSB—ADDRESS 0Ah
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
S
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
MSb
LSb
MSb
UNITS: 1.5625FV/R
LSb
SENSE
Figure 52. Current Register Format (Output)
MSB—ADDRESS 0Bh
LSB—ADDRESS 0BH
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
S
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
MSb
LSb
MSb
UNITS: 1.5625FV/R
LSb
SENSE
Figure 53. AverageCurrent Register Format (Output)
MSB—ADDRESS 1Ch
LSB—ADDRESS 1Ch
6
5
4
3
2
1
0
6
5
4
3
2
1
0
S
MAX MAX MAX MAX MAX MAX MAX
S
MIN MIN MIN MIN MIN MIN MIN
MSb
LSb
MSb
LSb
UNITS: 0.4mV/R
SENSE
Figure 54. MaxMinCurrent Register Format (Output)
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