DS2784 Maxim Integrated Products, DS2784 Datasheet - Page 13

• Manufacturer Part Number: DS2784
• Description: 1-Cell Stand-Alone Fuel Gauge IC
• Manufacturer: Maxim Integrated Products

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VOLTAGE MEASUREMENT
Battery voltage is measured every 440ms on the V
range and a 4.88mV resolution. The value is stored in the voltage register in two’s complement form and is updated
every 440ms. Voltages above the maximum register value are reported at the maximum value; voltages below the
minimum register value are reported at the minimum value.
VOLTAGE REGISTER FORMAT
TEMPERATURE MEASUREMENT
The DS2784 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.
TEMPERATURE REGISTER FORMAT
Note: Temperature and battery voltage (V
every 440ms.
CURRENT MEASUREMENT
The DS2784 continually measures the current flow into and out of the battery by measuring the voltage drop across
a low-value current-sense resistor, R
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 (3.52s). Charge currents above the
maximum register value are reported as 7FFFh. Discharge currents below the minimum register value are reported
as 8000h.
CURRENT REGISTER FORMAT
MSb
“S”: Sign Bit(s), “X”: Reserved
MSb
“S”: Sign Bit(s), “X”: Reserved
MSb
“S”: Sign Bit(s)
S
S
S
2
2
2
14
9
9
MSB—ADDRESS 0Ch
MSB—ADDRESS 0Ah
MSB—ADDRESS 0Eh
2
2
2
13
8
8
DS2784: 1-Cell Stand-Alone Fuel Gauge IC with Li+ Protector and SHA-1 Authentication
2
2
2
12
7
7
2
IN
2
2
11
) are measured using the same ADC. Therefore, measurements are a 220ms average updated
6
6
SNS
2
2
2
. The voltage-sense range between SNS and V
10
5
5
2
2
2
4
4
9
LSb
LSb
LSb
2
2
2
3
3
8
13 of 37
IN
pin with respect to V
MSb
MSb
MSb
2
2
2
2
2
7
2
2
2
1
1
6
LSB—ADDRESS 0Dh
LSB—ADDRESS 0Bh
LSB—ADDRESS 0Fh
2
2
2
0
0
5
SS
. Measurements have a 0 to 4.99V
2
X
X
4
2
X
X
3
Units: 1.5625μV/R
SS
2
X
X
is ±51.2mV. The input
2
Units: 4.886mV
Units: 0.125°C
2
X
X
1
LSb
LSb
LSb
2
X
X
SNS
0