BQ27742-G1 Datasheet, PDF (26/46 Pages) Texas Instruments – Single-Cell Li-Ion Battery Fuel Gauge with Programmable Hardware Protection

bq27742-G1
SLUSBV9C – MARCH 2014 – REVISED FEBRUARY 2016
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Communications (continued)
7.6.2.2 I²C Command Waiting Time
To ensure the correct results of a command with the 400-kHz I²C operation, a proper waiting time must be added
between issuing a command and reading the results. For subcommands, the following diagram shows the
waiting time required between issuing the control command and reading the status with the exception of the
checksum command. A 100-ms waiting time is required between the checksum command and reading the result.
For read-write standard commands, a minimum of 2 seconds is required to get the result updated. For read-only
standard commands, there is no waiting time required, but the host must not issue any standard command more
than two times per second. Otherwise, the gauge could result in a reset issue due to the expiration of the
watchdog timer.
xxx^xxSSxxx^xxxxx^xxAAxxx^xxDDxxx^xxDDRRxxx^xx[[66xxx^xx::00xxx^xx]] xxx^xx00xxx^xx
A
A
xxx^xxxxx^xxxxx^xxCCMMxxx^xxDDxxx^xx[[77xxx^xx::00xxx^xx]] xxx^xxxxx^xxAAxxx^xxxxx^xxSrxxx^xxDxxxxx^AATxxxxx^DADxxxxx^[7R:xxxxx^[06]xxxxx^:0]xxxxxxxx^A1xxx^{xxAxxxDxxxAxxxTDAxxxA[7xxxT:A0xxx][7xxx:0]xxxA}xxx^xxPxxx^xxAxxx
66Ps
DATA[7:0]
xxx^Nxxxxxx^Pxxx
66Ps
Waiting time between control subcommand and reading results
xxx^Sxxx_Dxxx^AAxxx^DTAxxx^D[R7xxx^[:60xxx^:]0xxx^] xxx_xxA0xxx_xx^A xxx_Dxxx_ATCxxx_AMxxx_[7Dxxx_:[07]xxx^:0]xxx_xxxxx_xxNxxx_xx^AP_xxx^xxSxxx^r xxx₆₆xxx^A_P^Dxxx_sDxxx^Rxxx^[6:xxx^0]xxxxxx¹xxx^A
xxxxxxxxx ^{DATA[7:0] A DATA[7:0]} xxx^Axxx
Waiting time between continuous reading results
Figure 18. I²C Command Waiting Time
The I²C clock stretch could happen in a typical application. A maximum 80-ms clock stretch could be observed
during the flash updates. There is up to a 270-ms clock stretch after the OCV command is issued.
7.7 Standard Data Commands
The fuel gauge uses a series of 2-byte standard commands to enable system reading and writing of battery
information. Each standard command has an associated command-code pair, as indicated in Table 8. Each
protocol has specific means to access the data at each Command Code. Data RAM is updated and read by the
gauge only once per second. Standard commands are accessible in NORMAL operation mode.
COMMAND NAME
Control()
AtRate()
UnfilteredSOC()
Temperature()
Voltage()
Flags()
NomAvailableCapacity()
FullAvailableCapacity()
RemainingCapacity()
FullChargeCapacity()
AverageCurrent()
TimeToEmpty()
FilteredFCC()
SafetyStatus()
UnfilteredFCC()
Imax()
UnfilteredRM()
FilteredRM()
Table 8. Standard Commands
COMMAND CODE
0x00 and 0x01
0x02 and 0x03
0x04 and 0x05
0x06 and 0x07
0x08 and 0x09
0x0A and 0x0B
0x0C and 0x0D
0x0E and 0x0F
0x10 and 0x11
0x12 and 0x13
0x14 and 0x15
0x16 and 0x17
0x18 and 0x19
0x1A and 0x1B
0x1C and 0x1D
0x1E and 0x1F
0x20 and 0x21
0x22 and 0x23
UNIT
—
mA
%
0.1°K
mV
—
mAh
mAh
mAh
mAh
mA
min
mAh
—
mAh
mA
mAh
mAh
SEALED ACCESS
RW
RW
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
26
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