Figure 8. accumulated current register format, acr – Rainbow Electronics DS2781 User Manual
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DS2781: Two-Cell Standalone Fuel Gauge IC
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ACR register update period). A write to the ACR forces the ADC to perform an offset correction conversion and
update the internal offset correction factor. Current measurement and accumulation begins with the second
conversion following a write to the ACR. Writing ACR clears the fractional values in ACRL. The Format of the ACR
register is shown in Figure 8, and the format of ACRL is shown in Figure 9.
In order to preserve the ACR value in case of power loss, the ACR value is backed up to EEPROM. The ACR
value is recovered from EEPROM on power-up. See the Memory Map in Table 2 for specific address location and
backup frequency.
Figure 8. Accumulated Current Register Format, ACR
ACR
R/W & EE
MSB—Address
10h LSB—Address
11h
2
15
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: 6.25
mVh/Rsns
Figure 9. Fractional/Low Accumulated Current Register Format, ACRL
ACRL
Read Only
MSB—Address
12h LSB—Address
13h
2
11
2
10
2
9
2
8
2
7
2
6
2
5
2
4
2
3
2
2
2
1
2
0
X X X X
MSb
LSb
MSb
LSb
“X”: reserved
Units:1.526nVHr/R
SNS
ACR LSb
R
SNS
VSS
-
VSNS
20m 15m 10m 5m
6.25 Vh 312.5 Ah 416.7 Ah 625 Ah 1.250mAh
ACR RANGE
R
SNS
VSS
-
VSNS
20m 15m 10m 5m
±409.6mVh ±20.48Ah ±27.30Ah ±40.96Ah ±81.92Ah