ds2760bx-025-t-r Maxim Integrated Products, Inc., ds2760bx-025-t-r Datasheet - Page 8

• Manufacturer Part Number: ds2760bx-025-t-r
• Description: Ds2760 High-precision Li+ Battery Monitor
• Manufacturer: Maxim Integrated Products, Inc.

Summary. All of the protection conditions described above are OR’ed together to affect the
outputs.
CURRENT MEASUREMENT
In the Active Mode of operation, the DS2760 continually measures the current flow into and out of the
battery by measuring the voltage drop across a current sense resistor. The DS2760 is available in two
configurations: (1) internal 25mW current sense resistor, and (2) external user-selectable sense resistor. In
either configuration, the DS2760 considers the voltage difference between pins IS1 and IS2 (V
V
flowing into the battery (charging), while a negative V
battery (discharging).
V
format every 88ms (128/fsample) with an average of 128 readings. Currents outside the range of the
register are reported at the limit of the range. The format of the Current Register is shown in Figure 4.
For the internal sense resistor configuration, the DS2760 maintains the Current Register in units of Amps,
with a resolution of 0.625mA and full scale range of no less than ±1.9A (see Note 7 on I
details). The DS2760 automatically compensates for internal sense resistor process variations and
temperature effects when reporting current.
For the external sense resistor configuration, the DS2760 writes the measured V
Register, with a resolution of 15.625mV and a full scale range of ±64mV.
CURRENT REGISTER FORMAT Figure 4
CURRENT ACCUMULATOR
The Current Accumulator facilitates remaining capacity estimation by tracking the net current flow into
and out of the battery. Current flow into the battery increments the Current Accumulator while current
flow out of the battery decrements it.
complement format. The format of the Current Accumulator is shown in Figure 5.
When the internal sense resistor is used, the DS2760 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
IS2
IS
is measured with a signed resolution of 12-bits. The current register is updated in two’s complement
) to be the filtered voltage drop across the sense resistor. A positive V
bit CE = 0) or (Sleep Mode)
DC
CC
MSb
S
= (Undervoltage) or (Overcurrent, EITHER Direction) or (Short Circuit) or
= (Overvoltage) or (Undervoltage) or (Overcurrent, Charge Direction) or (Protection Register
2
(Protection Register bit DE = 0) or (Sleep Mode)
11
MSB—Address 0E
2
10
2
9
2
8
2
7
2
6
Data is maintained in the Current Accumulator in two’s-
LSb
2
5
8
MSb
IS
2
4
value indicates current is flowing out of the
2
3
LSb—Address 0F
2
Units: 0.625 mA for internal sense resistor
2
15.625 mV for external sense resistor
2
1
IS
2
0
value indicates current is
IS
voltage to the Current
X
X
FS
spec for more
LSb
CC
X
IS
= V
and
IS1
DC
–