Rainbow Electronics MAX17047 - Manual (Page 27)

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MAX17047
ModelGauge m3 Fuel Gauge
Power-Up and Power-On Reset
Any power-on reset (POR) of the device resets all
memory locations to their default POR value. This
removes any custom cell characterization and applica-
tion data, affects ALRT interrupt and shutdown mode set-
tings, and resets all learned adjustments made by the fuel
gauge. To maintain accuracy of the fuel gauge and reset
operation settings of the device, the host must reload
all application memory data and restore all learned fuel-
gauge information. Note that the device may take up to
445ms to completely reset operation after a POR event
occurs. See
Figure 36 . Saved data should not be restored
until after this period is over. The following procedure is
recommended:
1) Read Status register. If POR = 0, exit.
2) Wait 600ms for POR operation to fully complete.
3) Restore all application register values.
4) Restore fuel gauge learned-value information (see the
Save and Restore Registers section).
5) Clear POR bit.
Save and Restore Registers
The device is designed to operate outside the battery
pack and can therefore be exposed to power loss when
in the application. To prevent the loss of learned informa-
tion during power cycles, a save-and-restore procedure
can be used to maintain register values in nonvolatile
memory external to the device. The registers (
Table 2 )
must be stored externally and then rewritten to the device
after power-up to maintain a learned state of operation.
Table 2. Save and Restore Registers
Figure 36. Power-Up Operation
REGISTER ADDRESS
FullCap 10h
Cycles 17h
RCOMP0 38h
TempCo 39h
QResidual 00 12h
QResidual 10 22h
QResidual 20 32h
QResidual 30 42h
dQacc 45h
dPacc 46h
AIN
V BATT
A/D
READINGS
OUTPUT
REGISTERS
1.4s UNTIL NEXT TEMPERATURE READING
270ms
175ms
CELL
INSERTION
V BATT > V DDMIN
A/D
MEASUREMENTS
COMPLETE
SOC VALUES
UPDATED