MAX17047 Datasheet, PDF (18/47 Pages) Maxim Integrated Products – ModelGauge m3 Fuel Gauge

MAX17047/MAX17050
ModelGauge m3 Fuel Gauge
Alternatively, the TTE register can be used to estimate time
to empty for any given current load. Whenever the AtRate
register is programmed to a negative number, representing
a discharge current, the TTE register displays the estimated
time to empty for the application based on the AtRate regis-
ter value. Figure 17 shows the TTE register format.
Age Register (07h)
The Age register contains a calculated percentage value
of the application’s present cell capacity compared to its
expected capacity. The result can be used by the host to
gauge the cell’s health as compared to a new cell of the
same type. The result is displayed as a percentage value
from 0 to 256% with a 0.0039% LSb. Figure 18 shows the
Age register format. The equation for the register output is:
Age Register = 100% O (FullCAP Register/
DesignCap Register)
Cycles Register (17h)
The Cycles register accumulates total percent change in
the cell during both charging and discharging. The result
is stored as a total count of full charge/discharge cycles.
For example, a full charge/discharge cycle results in
the Cycles register incrementing by 100%. The Cycles
register has a full range of 0 to 65535% with a 1% LSb.
This register is reset to 0% at power-up. To maintain the
lifetime cycle count of the cell, this register must be peri-
odically saved by the host and rewritten to the device at
power-up. See the Save and Restore Registers section
for details. See Figure 19 for the Cycles register format.
VFOCV Register (FBh)
The VFOCV register contains the raw open-circuit volt-
age output of the voltage fuel gauge. This value is used
in other internal calculations and can be read for debug
purposes. The result is a 12-bit value ranging from 2.5V
to 5.119V where 1 LSb is 1.25mV. The bottom 4 bits of
this register are don’t care bits. See Figure 20 for the
VFOCV register format.
2¹⁰ 2⁹
MSb
MSB—ADDRESS 11h
2⁸ 2⁷ 2⁶ 2⁵
2⁴ 2³
LSb
Figure 17. TTE Register Format (Output)
LSB—ADDRESS 11h
2² 2¹ 2⁰ 2^-1 2^-2 2^-3 2^-4 2^-5
MSb
LSb
2⁰ UNITS: 3.0min
2⁷ 2⁶
MSb
MSB—ADDRESS 07h
2⁵ 2⁴ 2³ 2²
2¹ 2⁰
LSb
Figure 18. Age Register Format (Output)
LSB—ADDRESS 07h
2^-1 2^-2 2^-3 2^-4 2^-5 2^-6 2^-7 2^-8
MSb
LSb
2⁰ UNITS: 1.0%
2^-8 UNITS: 0.0039%
MSB—ADDRESS 17h
2¹⁵ 2¹⁴ 2¹³ 2¹² 2¹¹ 2¹⁰ 2⁹ 2⁸
MSb
LSb
Figure 19. Cycles Register Format (Output)
LSB—ADDRESS 17h
2⁷ 2⁶ 2⁵ 2⁴ 2³ 2²
MSb
2⁰ UNITS: 1.0%
2¹ 2⁰
LSb
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