Fuel Gauge - LG TU750 Service Manual

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.
G2 G1
3 2 1
BATT_GND
Name
FGSENSEP
FGSENSEN
LGE Internal Use Only
FGS+
2012
R324
Route as a differential pair
1/4W
0.025
1%
FGS-
Fig. 3-5-4 The Schematic of the fuel gauge block
Type Unused
Analog VBAT
Analog VBAT
Table 3-5-2. Fuel Gauge channel spec
SRST_n
SCLK
SDAT
BDATA
FGS+
FGS-
VBAT_D
CHS+
CHS-
CHREG
DCIO_INT
Description
Fuel gauge current sensing input positive
Fuel gauge current sensing input negative
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M2
SRST_N
M1
SCLK
N3
SDAT
A11
BDATA
J14
FGSENSEP
C325
47p
J13
FGSENSEN
G2
VBAT_D
H1
CHSENSEP
H2
CHSENSEN
H3
CHREG
Only for training and service purposes