Current Blanking
The current blanking feature modifies the current mea-
surement result prior to being accumulated in the ACR.
Current blanking occurs conditionally when a current
measurement (raw current + COB) falls in one of two
defined ranges. The first range prevents charge cur-
rents less than 100µV from being accumulated. The
second range prevents discharge currents less than
25µV in magnitude from being accumulated. Charge-
current blanking is always performed, however, dis-
charge-current blanking must be enabled by setting
the NBEN bit in the Control register. See the register
description for additional information.
Accumulation Bias
The Accumulation Bias (AB) register allows an arbitrary
bias to be introduced into the current-accumulation
process. The AB can be used to account for currents
that do not flow through the sense resistor, estimate
currents too small to measure, estimate battery self-dis-
charge, or correct for static offset of the individual
DS2788 device. The AB register allows a user-pro-
grammed positive or negative constant bias to be
included in the current accumulation process. The
user-programmed two’s complement value, with bit
weighting the same as the Current register, is added to
the ACR once per current conversion cycle. The AB
value is loaded on power-up from EEPROM memory.
Figure 10 shows the format of the AB register.
DS2788
Stand-Alone Fuel-Gauge IC with
LED Display Drivers
______________________________________________________________________________________ 11
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: 1.526 nVHr/R
SNS
Figure 9. Fractional/Low Accumulated Current Register (ACRL) Format
ACR LSb
R
SNS
V
SS
- V
SNS
20m 15m 10m 5m
6.25µVh 312.5µAh 416.7µAh 625µAh 1.250mAh
ACR RANGE
R
SNS
V
SS
- V
SNS
20m 15m 10m 5m
±409.6mVh ±20.48Ah ±27.30Ah ±40.96Ah ±81.92Ah
Figure 10. Accumulation Bias Register Formats
ADDRESS 61h
S 2
6
2
5
2
4
2
3
2
2
2
1
2
0
MSb LSb
“S”: SIGN BIT(S) UNITS: 1.562 5µV/R
SNS
AB
EE
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