ds2786 Maxim Integrated Products, Inc., ds2786 Datasheet - Page 12

• Manufacturer Part Number: ds2786
• Description: Ds2786 Standalone Ocv-based Fuel Gauge
• Manufacturer: Maxim Integrated Products, Inc.

Figure 13. Blanking/OCV Threshold Register Format
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
OCV CELL MODEL
The OCV cell model is a 9-point piece-wise linear approximation of open circuit cell voltage versus the remaining
capacity of the cell. Whenever an OCV update occurs, the Relative Capacity Register is adjusted to a new value
based on the OCV voltage reading and a linear approximation of the table values. Figure 15 shows the factory-
default cell model stored in EEPROM.
MSb
SMOD LDIS VODIS ITEMP
MSb
2
7
2
6
2
5
12 of 22
Address 7Bh
Address 7Ch
2
4
Units: 1.22mV/15min
2
2
3
3
Units: 25μV/R
2
2
2
2
2
2
1
1
LSb
LSb
2
2
SNS
0
0