Datasheet
DS2786 Stand-Alone OCV-Based Fuel Gauge
9 of 22
TEMPERATURE MEASUREMENT
The DS2786 uses an integrated temperature sensor to measure battery temperature with a resolution of 0.125°C.
Temperature measurements are updated every 1760ms and placed in the Temperature Register in two’s
complement form. The format of the Temperature Register is shown in Figure 7. The ITEMP bit in the
Status/Configuration Register must be set to enable the internal temperature measurement instead of the AIN1
measurement.
Figure 7. Temperature Register Format
MSB—Address 0Ah LSB—Address 0Bh
S 2
9
2
8
2
7
2
6
2
5
2
4
2
3
2
2
2
1
2
0
X X X X X
MSb LSb MSb LSb
“S”: sign bit(s), “X”: reserved
Units: 0.125C
CURRENT MEASUREMENT
In the Active mode of operation, the DS2786 continually measures the current flow into and out of the battery by
measuring the voltage drop across a low-value current-sense resistor, R
SNS
, connected between the SNS and V
SS
pins. The voltage sense range between SNS and V
SS
is ±51.2mV. Note that positive current values occur when
V
SNS
is less than V
SS
, and negative current values occur when V
SNS
is greater than V
SS
. Peak signal amplitudes up
to 102mV are allowed at the input as long as the continuous or average signal level does not exceed ±51.2mV over
the conversion cycle period. The ADC samples the input differentially and updates the Current Register every
880ms at the completion of each conversion cycle. Figure 8 describes the Current Measurement Register format
and resolution for each option. Charge currents above the maximum register value are reported at the maximum
value (7FFFh = +51.2mV). Discharge currents below the minimum register value are reported at the minimum
value (8000h = -51.2mV).
Every 1024th conversion, the ADC measures its input offset to facilitate offset correction to improve Current
accuracy. Offset correction occurs approximately every 15 minutes. The resulting correction factor is applied to the
subsequent 1023 measurements. During the offset correction conversion, the ADC does not make a measurement.
The current measurement just prior to the offset conversion is displayed in the Current Register.
Figure 8. Current Register Formats
MSB—Address 0Eh LSB—Address 0Fh
S 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
“S”: sign bit
Units: 25V/R
SNS