BQ27541-V200_1007 Datasheet, PDF (35/43 Pages) Texas Instruments – Single Cell Li-Ion Battery Fuel Gauge for Battery Pack Integration

bq27541-V200
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SLUSA11 – FEBRUARY 2010
I²C Command Waiting Time
To make sure the correct results of a command with the 400KHz I²C operation, a proper waiting time should be
added between issuing command and reading results. For subcommands, the following diagram shows the
waiting time required between issuing the control command the reading the status with the exception of the
checksum command. A 100ms waiting time is required between the checksum command and reading 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 should not issue all standard commands
more than two times per second. Otherwise, the gauge could result in a reset issue due to the expiration of the
watchdog timer.
S ADDR[6:0] 0 A
S ADDR[6:0] 0 A
CMD[7:0]
CMD[7:0]
A DATA [7:0] A DATA [7:0] A P 66ms
A Sr ADDR[6:0] 1 A DATA [7:0] A DATA [7:0]
Waiting time between control subcommand and reading results
N P 66ms
S ADDR[6:0] 0 A CMD[7:0] A Sr ADDR[6:0] 1 A DATA [7:0] A DATA [7:0] A
DATA [7:0] A DATA [7:0] N P 66ms
Waiting time between continuous reading results
The I²C clock stretch could happen in a typical application. A maximum 80ms clock stretch could be observed
during the flash updates. There is up to 270ms clock stretch after the OCV command is issued.
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