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LGE Internal Use Only
Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes
3. TECHNICAL BRIEF
3.5.1 Fuel Gauge
AB3100 supports the measurement of the current consumption/charging current in the U301 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.2-5-3). 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.
Name
Type
Unused
Description
FGSENSEP
Analog
VBAT
Fuel gauge current sensing input positive
FGSENSEN
Analog
VBAT
Fuel gauge current sensing input negative
Table 3-5-2. Fuel Gauge channel spec
Fig. 3-5-4 The Schematic of the fuel gauge block
Route as a differential pair
Phone ground return path
BATT_GND
CN301
G1
G2
1
2
3
0.025
1%
2012
R324
1/4W
FGS+
FGS-
VBAT_D
M2
SRST_N
G2
SCLK
M1
SDAT
N3
FGSENSEN
J13
FGSENSEP
J14
H3
CHREG
CHSENSEN
H2
CHSENSEP
H1
A11
BDATA
47p
C325
VBAT_D
FGS-
FGS+
DCIO_INT
BDATA
CHREG
CHS-
CHS+
SRST_n
SCLK
SDAT