DS2782G+T&R Maxim Integrated Products, DS2782G+T&R Datasheet - Page 10

• Manufacturer Part Number: DS2782G+T&R
• Description: IC FUEL GAUGE BATT 10-TDFN
• Manufacturer: Maxim Integrated Products

Specifications of DS2782G+T&R

• Function: Fuel, Gas Gauge/Monitor
• Battery Type: Lithium-Ion (Li-Ion), Lithium-Polymer (Li-Pol)
• Voltage - Supply: 2.5 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 10-TDFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

DS2782
CURRENT ACCUMULATION
Current measurements are internally summed, or accumulated, at the completion of each conversion period with
the results displayed in the Accumulated Current Register (ACR). The accuracy of the ACR is dependent on both
the current measurement and the conversion time base. The ACR has a range of 0 to 409.6mVh with an LSb of
6.25Vh. Additional read-only registers (ACRL) hold fractional results of each accumulation to avoid truncation
errors. Accumulation of charge current above the maximum register value is reported at the maximum register
value (7FFFh); conversely, accumulation of discharge current below the minimum register value is reported at the
minimum value (8000h).
Charge currents (positive Current register values) less than 100V are not accumulated in order to mask the effect
of accumulating small positive offset errors over long periods. This limits the minimum charge current, for coulomb-
counting purposes, to 5mA for RSNS = 0.020 and 20mA for RSNS = 0.005.
Read and write access is allowed to the ACR. The ACR must be written MSByte first then LSByte. Whenever the
ACR is written, the fractional accumulation result bits are cleared. The write must be completed within 3.515s (one
ACR register update period). A write to the ACR forces the ADC to perform an offset correction conversion and
update the internal offset correction factor. Current measurement and accumulation begins with the second
conversion following a write to the ACR. Writing ACR clears the fractional values in ACRL. The Format of the ACR
register is shown in Figure 8, and the format of ACRL is shown in Figure 9.
In order to preserve the ACR value in case of power loss, the ACR value is backed up to EEPROM. The ACR
value is recovered from EEPROM on power-up. See the Memory Map in Table 2 for specific address location and
backup frequency.
Figure 8. Accumulated Current Register Format, ACR
R/W & EE
ACR
MSB—Address 10h
LSB—Address 11h
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
MSb
LSb
MSb
LSb
Units:
6.25Vh/Rsns
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