DS2786G+ Maxim Integrated Products, DS2786G+ Datasheet - Page 13

• Manufacturer Part Number: DS2786G+
• Description: IC FUEL GAUGE OCV 10-TDFN
• Manufacturer: Maxim Integrated Products

Specifications of DS2786G+

• Function: Fuel, Gas Gauge/Monitor
• Battery Type: Lithium-Ion (Li-Ion), Lithium-Polymer (Li-Pol)
• Voltage - Supply: 2.5 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 10-TDFN Exposed Pad
• Operating Supply Voltage: 2.5 V to 5.5 V
• Supply Current: 50 uA
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Charge Safety Timers: No
• Mounting Style: SMD/SMT
• Temperature Monitoring: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

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.
Figure 15. Default OCV Cell Model
The OCV cell model can be modified by changing the Capacity and Voltage Breakpoint Registers in EEPROM.
Capacity 0 is fixed at 0% and cannot be changed. Capacity 1 through Capacity 7 are stored with 0.5% resolution at
addresses 61h through 67h respectively. Capacity values must be monotonic (Capacity 1 > Capacity 0, Capacity 2
> Capacity 1, etc.), but otherwise can be written to any value between 0.5% to 99.5%. Capacity 8 is fixed at a value
of 100% and cannot be changed.
Voltage breakpoints require two bytes per breakpoint, but are otherwise stored in a similar manner. Voltage
Breakpoint 0: MSB stored at address 68h, LSB stored at address 69h. Other voltage breakpoints stored
sequentially through address location 79h. Each voltage breakpoint has a resolution of 1.22mV, and a range from
0.0V to 4.996V (IC operation limited to 4.5V). Voltage breakpoint values must also be monotonic.
Figure 16. Capacity 1 to Capacity 7 Registers Format
100%
Breakpoint 8
4.171V
100%
80%
Breakpoint 6
4.042
85%
MSb
2
Breakpoint 5
7
Breakpoint 7
4.005
80%
60%
4.087V
90.5%
2
6
2
Address 61h–67h
5
13 of 22
2
4
2
3
40%
Breakpoint 4
2
DS2786 Stand-Alone OCV-Based Fuel Gauge
2
3.831V
52.5%
Breakpoint 3
Units: 0.5%
3.752
2
25%
1
LSb
2
0
20%
Breakpoint 1
3.619V
Breakpoint 0
5%
3.186V
Breakpoint 2
0%
3.673V
10%
0%
4.2
4
3.8
3.6
3.4
3.2
3