DS2788 MAXIM [Maxim Integrated Products], DS2788 Datasheet - Page 11

• Manufacturer Part Number: DS2788
• Description: Stand-Alone Fuel-Gauge IC with LED Display Drivers
• Manufacturer: MAXIM [Maxim Integrated Products]

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.
Figure 9. Fractional/Low Accumulated Current Register (ACRL) Format
Figure 10. Accumulation Bias Register Formats
AB
ACRL
“X”: reserved
MSb
2
11
2
10
2
______________________________________________________________________________________
9
MSB—ADDRESS 12h
±409.6mVh
V
V
SS
6.25μVh
SS
2
- V
- V
8
SNS
SNS
Current Blanking
“S”: SIGN BIT(S)
MSb
2
S
7
2
312.5μAh
±20.48Ah
2
6
Stand-Alone Fuel-Gauge IC with
20m
20m
6
2
5
2
5
LSb
ADDRESS 61h
2
4
ACR RANGE
2
4
416.7μAh
±27.30Ah
ACR LSb
15m
15m
2
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.
3
MSb
2
R
R
UNITS: 1.5625μV/R
3
SNS
SNS
2
2
LED Display Drivers
±40.96Ah
2
625μAh
2
10m
10m
2
1
2
1
LSB—ADDRESS 13h
LSb
2
SNS
0
2
0
1.250mAh
Accumulation Bias
±81.92Ah
5m
5m
X
Units: 1.526nVHr/R
X
READ ONLY
X
LSb
SNS
X
EE
11