DS2786 Stand-Alone OCV-Based Fuel Gauge

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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: 0.125

C

CURRENT MEASUREMENT

In the Active mode of operation, the DS2786 continually measures the current flow into and out of the battery by

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: 25