BQ27532-G1 Datasheet, PDF (20/35 Pages) Texas Instruments – Battery Management Unit Impedance Track Fuel Gauge

bq27532-G1
SLUSBU6B – SEPTEMBER 2014 – REVISED JANUARY 2016
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7.5.4.4 I²C Clock Stretching
A clock stretch can occur during all modes of fuel gauge operation. In SLEEP and HIBERNATE modes, a short
clock stretch occurs on all I²C traffic as the device must wake-up to process the packet. In the other modes
(INITIALIZATION, NORMAL) clock stretching only occurs for packets addressed for the fuel gauge. The majority
of clock stretch periods are small as the I²C interface performs normal data flow control. However, less frequent
yet more significant clock stretch periods may occur as blocks of data flash are updated. The following table
summarizes the approximate clock stretch duration for various fuel gauge operating conditions.
GAUGING
MODE
SLEEP
HIBERNATE
INITIALIZATION
NORMAL
Table 4. Approximate Clock Stretch Duration
OPERATING CONDITION / COMMENT
Clock stretch occurs at the beginning of all traffic as the device wakes up.
Clock stretch occurs within the packet for flow control (after a start bit, ACK or first data bit).
Normal Ra table data flash updates.
Data flash block writes.
Restored data flash block write after loss of power.
End of discharge Ra table data flash update.
APPROXIMATE
DURATION
≤ 4 ms
≤ 4 ms
24 ms
72 ms
116 ms
144 ms
20
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