MAX17047/MAX17050
ModelGauge m3 Fuel Gauge
of the cell by comparing against the calculated pres-
ent capacity stored in the FullCAP register. DesignCap
has an LSb equal to 5.0FVh and a full range of 0 to
327.68mVh. The user should multiply the mAh capac-
ity of the cell by the sense resistor value to determine
the FVh value to store in the DesignCap register. The
DesignCap register format is shown in Figure 24.
QH Register (4Dh)
The QH register displays the raw coulomb count gener-
ated by the device. This register is used internally as an
input to the mixing algorithm. Monitoring changes in QH
over time can be useful for debugging device operation.
The QH register is set to 0000h at power-up. The QH reg-
ister format is shown in Figure 23.
FullSOCThr Register (13h)
The FullSOCThr register gates detection of end-of-
Application-Specific Registers
charge. SOC
must be larger than the FullSOCThr
VF
The following registers define the behavior of the applica-
tion. They must be programmed by the user before the
ModelGauge m3 algorithm is accurate. Any changes to
these register values require recharacterization of the cell.
valuebeforeICHGTermiscomparedtotheAverageCurrent
register value. The recommended FullSOCThr register
setting for most applications is 95%. See the ICHGTerm
register description for details. The FullSOCThr register
is 70% at power-up. Figure 25 is the FullSOCThr register
format.
DesignCap Register (18h)
The DesignCap register holds the expected capacity of
the cell. This value is used to determine age and health
MSB—ADDRESS 23h
LSB—ADDRESS 23h
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
0
LSb
2 UNITS: 5.0FVh/R
SENSE
(0.5mAh WHEN R
= 0.010I)
SENSE
Figure 23. QH Register Format (Output)
MSB—Address 4Dh
LSB—ADDRESS 4Dh
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
0
LSb
2 UNITS: 5.0FVh/R
SENSE
(0.5mAh WHEN R
= 0.010I)
SENSE
Figure 24. DesignCap Register Format (Input)
MSB—ADDRESS 18h
LSB—ADDRESS 18h
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
0
LSb
2 UNITS: 5.0FVh/R
SENSE
(0.5mAh WHEN R
= 0.010I)
SENSE
Figure 25. FullSOCThr Register Format (Input)
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