DS2755: High-Accuracy Battery Fuel Gauge with Snapshot

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Figure 9. INTERRUPT THRESHOLD REGISTER FORMATS

Current Accumulator Interrupt High Threshold

MSB—Address 80

LSB—Address 81

S

2

14

2

13

2

12

2

11

2

10

2

9

2

8

2

7

2

6

2

5

2

4

2

3

2

2

2

1

2

0

MSb

LSb

MSb

LSb

Units: 6.25

μVhrs

Current Accumulator Interrupt Low Threshold

MSB—Address 82

LSB—Address 83

S

2

14

2

13

2

12

2

11

2

10

2

9

2

8

2

7

2

6

2

5

2

4

2

3

2

2

2

1

2

0

MSb

LSb

MSb

LSb

Units: 6.25

μVhrs

Temperature Interrupt High Threshold

Address 84

S

2

6

2

5

2

4

2

3

2

2

2

1

2

0

MSb

LSb

Units: 1.0°C

Temperature Alarm Low Threshold

Address 85

S

2

6

2

5

2

4

2

3

2

2

2

1

2

0

MSb

LSb

Units: 1.0°C

SNAPSHOT MODE

Measurement of the current and voltage can be synchronized to a system event with the Snapshot mode.

Triggering a Snapshot event causes the ADC to abandon the current conversion and capture one current and one

voltage sample. The Snapshot results are reported in the Current and Voltage registers for retrieval by the host.

Normal current, voltage and temperature measurements and current accumulation resume immediately following a

Snapshot event, though the Snapshot current and voltage values persist until the host system writes the SNAP bit

in the Special Function Register to a 0. Since the snapshot mode disrupts the continuity of the coulomb counting

process, it should be used sparingly.

The Sync Function Command [D2h] signals the ADC control to expect a Snapshot trigger on DQ. Following the

Sync command, the host can trigger a Snapshot event by toggling the DQ line. Synchronization occurs on the