Datasheet
DS2786 Stand-Alone OCV-Based Fuel Gauge
12 of 22
OCV DETECTION AND CURRENT BLANKING
The Blanking/OCV Threshold Register sets the current measurement level at which the DS2786 switches between
coulomb counting and open-circuit voltage measurement. When the magnitude of the measured current (after
COBR is applied) is less than the value defined by the Blanking/OCV Threshold Register, the measurement is not
summed into the IACR. Instead, the IACR is maintained at its present value and the DS2786 begins dV/dt
measurement evaluation to detect an OCV voltage condition. A threshold value that is below the minimum
operational current, but above the maximum idle current of the application should be selected. The Blanking/OCV
Threshold Register has a resolution of 25V/R
SNS
, and a range from 0mV/R
SNS
to 6.375mV/R
SNS
. The factory
default value is 06h
Figure 13. Blanking/OCV Threshold Register Format
Address 7Bh
2
7
2
6
2
5
2
4
2
3
2
2
2
1
2
0
MSb LSb
Units: 25V/R
SNS
While the measured current is below the Blanking/OCV Threshold level, the DS2786 actively searches for a
relaxed cell by calculating the change in cell voltage as reported in the Voltage Register over 15 minute intervals
(dV/dt). If the 15 minute dV/dt change of the Voltage Register is less than the value stored in the OCV dV/dt
Threshold Register, the DS2786 determines that the cell is now in a relaxed state and the Relative Capacity
Register is adjusted based on the OCV cell model stored in parameter EEPROM. This operation will occur
repeatedly every 15 minutes until the DS2786 returns to coulomb-counting mode of operation.
The OCV dV/dt Threshold Register has a resolution of 1.22mV/15min and a range from 0mV/15min to
18.3mV/15min. The factory default value is 3.66mV/15min. Note that the upper 4 bits of the OCV dV/dt Threshold
Register are used to EEPROM back bits from the Status/Configuration Register.
Figure 14. OCV dV/dt Threshold Register Format
Address 7Ch
SMOD LDIS VODIS ITEMP
2
3
2
2
2
1
2
0
MSb LSb
Units: 1.22mV/15min