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Averagecurrent register (0bh), Maxmincurrent register (1ch), Cgain register 2eh/coff register (2fh) – Rainbow Electronics MAX17047 User Manual

Page 37: Figure 52. averagecurrent register forma, Figure 53. maxmincurrent register format

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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 descrip-

tion for details on setting the time filter. The resulting

average is placed in the AverageCurrent register with
an LSb value of 1.5625FV/R

SENSE

. The first Current

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 52

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

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
values with 0.4mV/R

SENSE

resolution.

Figure 53

shows

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:

Current Register = Current A/D Reading O

(CGAIN Register/16384) + (2 O COFF Register)

Figure 53. MaxMinCurrent Register Format (Output)

Figure 52. AverageCurrent Register Format (Output)

Figure 53

MSB—ADDRESS 1Ch

LSB—ADDRESS 1Ch

S

MAX

6

MAX

5

MAX

4

MAX

3

MAX

2

MAX

1

MAX

0

S

MIN

6

MIN

5

MIN

4

MIN

3

MIN

2

MIN

1

MIN

0

MSb

LSb

MSb

LSb

UNITS: 0.4mV/R

SENSE

Figure 52

MSB—ADDRESS 0Bh

LSB—ADDRESS 0BH

S

2

14

2

13

2

12

2

11

2

10

2

9

2

8

2

7

2

6

2

5

2

4

2

3

2

2

2

1

2

0

MSb

LSb

MSb

LSb

UNITS: 1.5625FV/R

SENSE