DS2761

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When the internal sense resistor is used, the DS2761 maintains the current accumulator in units of amp-

hours, with a resolution of 0.25mAhrs and full-scale range of

±8.2Ahrs. When using an external sense

resistor, the DS2761 maintains the current accumulator in units of volt-hours, with a resolution of

6.25

mVhrs and a full scale range of ±205mVhrs.

The current accumulator is a read/write register that can be altered by the host system as needed.

Figure 5. CURRENT ACCUMULATOR FORMAT

MSB—Address 10

LSB—Address 11

MSb

LSb

MSb

LSb

Units: 0.25mAhrs for Internal Sense Resistor

6.25

mVhrs for External Sense Resistor

CURRENT OFFSET COMPENSATION

Current measurement and current accumulation are both internally compensated for offset on a continual

basis minimizing error resulting from variations in device temperature and voltage. Additionally, a

constant bias can be utilized to alter any other sources of offset. This bias resides in EEPROM address

33h in two’s-complement format and is subtracted from each current measurement. The current offset

bias is applied to both the internal and external sense resistor configurations. The factory default for the

current offset bias is a value of 0.

Figure 6. CURRENT OFFSET BIAS

Address 33

MSb

LSb

Units: 0.625mA for Internal Sense Resistor

15.625

mV for External Sense Resistor

VOLTAGE MEASUREMENT

voltage register is updated in two’s-complement format every 3.4ms with a resolution of 4.88mV.

Voltages above the maximum register value are reported as the maximum value. The voltage register

format is shown in Figure 7.