LG KT520 Service Manual page 66

3.5.1 Fuel Gauge
AB3000 supports the measurement of the current consumption/charging current in the KT520 with a
fuel gauge block. By constantly integrating the current flowing into and out of the battery, the fuel
gauge block is used to determine the remaining battery capacity.
The function of the fuel gauge block is schematically described in (Fig.3-5-3). A sense resistor
R_FGSENSE is connected in series with the battery. The voltage across the resistor, equivalent to the
current entering/leaving the battery, is integrated using an ADC block.
Fig. 3-5-3. The analog front-end of the fuel gauge block
Name Type
FGSENSE+ Analog
FGSENSE- Analog
Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes
Fig. 3-5-4 The Schematic of the fuel gauge block
Unused
VBAT
VBAT
Table 3-5-2. Fuel Gauge channel spec
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3. TECHNICAL BRIEF
Description
Fuel gauge current sensing input positive
Fuel gauge current sensing input negative
LGE Internal Use Only