DS2760 Dallas Semiconducotr, DS2760 Datasheet - Page 9

• Manufacturer Part Number: DS2760
• Description: High Precision Li-Ion Battery Monitor
• Manufacturer: Dallas Semiconducotr

When the internal sense resistor is used, the DS2760 maintains the Current Accumulator in units of Amp-
hours, with a resolution of 0.25 mAhrs and full scale range of 8.2 Ahrs. When using an external sense
resistor, the DS2760 maintains the Current Accumulator in units of Volt-hours, with a resolution of
6.25 Vhrs and a full scale range of 205 mVhrs.
The Current Accumulator is a read/write register that can be altered by the host system as needed.
CURRENT ACCUMULATOR FORMAT – Figure 5
CURRENT OFFSET COMPENSATION
CURRENT MEASUREMENT and the 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 may 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.
CURRENT OFFSET BIAS – Figure 6
VOLTAGE MEASUREMENT
The DS2760 continually measures the voltage between pins VIN and VSS over a range of 0 to 5-volts.
The resulting data is placed in the Voltage Register in two’s-complement format with a resolution of
4.88 mV. Voltages above the maximum register value are reported as the maximum value. The Voltage
Register format is shown in Figure 7.
VOLTAGE REGISTER FORMAT – Figure 7
MSb
MSb
S
S
2
2
14
9
MSB—Address 0C
MSB—Address 10
2
2
13
8
2
2
12
7
2
2
11
MSb
6
S
2
2
10
5
2
6
2
2
9
4
2
Units: 0.625 mA for internal sense resistor
5
LSb
LSb
Address 33
2
2
8
3
15.625 V for external sense resistor
2
9 of 25
4
2
MSb
3
MSb
2
2
7
2
2
2
2
2
6
1
Units: 0.25 mAhrs for internal sense resistor
2
1
LSB—Address 0D
LSB—Address 11
2
2
LSb
5
0
6.25 Vhrs for external sense resistor
2
0
2
X
4
2
X
3
2
X
2
Units: 4.88 mV
2
X
1
LSb
LSb
2
X
0
DS2760