Datasheet
DS2782
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VIN is usually connected to the positive terminal of a single cell Lithium-Ion battery via a 1k resistor. The input
impedance is sufficiently large (15M) to be connected to a high impedance voltage divider in order to support
multiple cell applications. The pack voltage should be divided by the number of series cells to present a single cell
average voltage to the VIN input. In Figure 3, the value of R can be up to 1M without incurring significant error
due to input loading.
TEMPERATURE MEASUREMENT
The DS2782 uses an integrated temperature sensor to measure battery temperature with a resolution of 0.125°C.
Temperature measurements are updated every 440ms and placed in the temperature register in two’s complement
form. The format of the temperature register is shown in Figure 5.
Figure 5. Temperature Register Format
TEMP
Read Only
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: 0.125C
CURRENT MEASUREMENT
In the ACTIVE mode of operation, the DS2782 continually measures the current flow into and out of the battery by
measuring the voltage drop across a low-value current-sense resistor, R
SNS
. The voltage-sense range between
SNS and VSS is ±51.2mV. The input linearly converts peak signal amplitudes up to 102.4mV as long as the
continuous signal level (average over the conversion cycle period) does not exceed ±51.2mV. The ADC samples
the input differentially at 18.6kHz and updates the Current register at the completion of each conversion cycle.
The Current register is updated every 3.515s with the current conversion result in two’s complement form. 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).
Figure 6. Current Register Format
CURRENT
Read Only
MSB—Address 0Eh LSB—Address 0Fh
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
“S”: sign bit(s)
Units: 1.5625V/Rsns
CURRENT RESOLUTION (1 LSB)
R
SNS
VSS
-
VSNS
20m 15m 10m 5m
1.5625V 78.13A 104.2A 156.3A 312.5A