Current blanking, Accumulation bias – Rainbow Electronics DS2788 User Manual
Page 11
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.
D
S
2
7
8
8
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: 1.526nVHr/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: 1.5625µV/R
SNS
AB
EE