A

A

S

0

ADDR [6:0]

CMD [7:0]

Sr

1

ADDR [6:0]

A

DATA [7:0]

A

DATA [7:0]

P

N

A

A

S

A

0

P

ADDR [6:0]

CMD [7:0]

DATA [7:0]

DATA [7:0]

A

66 s

m

A

A

S

0

ADDR [6:0]

CMD [7:0]

Sr

1

ADDR [6:0]

A

DATA [7:0]

A

DATA [7:0]

A

DATA [7:0]

A

DATA [7:0]

P

N

Waiting time inserted between incremental 2-byte write packet for a subcommand and reading results

(acceptable for

100 kHz)

f

Waiting time inserted after incremental read

66 s

m

66 s

m

A

A

S

0

ADDR [6:0]

CMD [7:0]

Sr

1

ADDR [6:0]

A

DATA [7:0]

A

DATA [7:0]

P

N

A

A

S

A

0

P

ADDR [6:0]

CMD [7:0]

DATA [7:0]

66 s

m

Waiting time inserted between two 1-byte write packets for a subcommand and reading results

(required for 100 kHz < f

400 kHz)

66 s

m

A

A

S

A

0

P

ADDR [6:0]

CMD [7:0]

DATA [7:0]

66 s

m

17

bq27320

www.ti.com

SLUSCG9A – FEBRUARY 2016 – REVISED MARCH 2016

Product Folder Links: bq27320

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Copyright © 2016, Texas Instruments Incorporated

A clock stretch can occur during all modes of fuel gauge operation. In SNOOZE and HIBERNATE modes, a short

INSERT CHECK, NORMAL) clock stretching only occurs for packets addressed for the fuel gauge. The majority

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

Operating Condition/Comment

Approximate

Duration

SLEEP

HIBERNATE

Clock stretch occurs at the beginning of all traffic as the device wakes up.

≤ 4 ms

BAT INSERT

CHECK

NORMAL

Clock stretch occurs within the packet for flow control (after a start bit, ACK or first data bit).

≤ 4 ms

Data flash block writes.

72 ms

Restored data flash block write after loss of power.

116 ms

8.4 Device Functional Modes

To minimize power consumption, the device has different power modes: NORMAL, SNOOZE, SLEEP,

HIBERNATE, and BAT INSERT CHECK. The bq27320 passes automatically between these modes, depending

upon the occurrence of specific events, though a system processor can initiate some of these modes directly.

•

In NORMAL mode, the gas gauge is fully powered and can execute any allowable task.

•

In SNOOZE mode, low-frequency and high-frequency oscillators are active. Although the SNOOZE mode has

higher current consumption than the SLEEP mode, it is also a reduced power mode.

•

In SLEEP mode, the gas gauge turns off the high-frequency oscillator and exists in a reduced-power state,

periodically taking measurements and performing calculations.

•

In HIBERNATE mode, the gas gauge is in a low-power state, but can be woken up by communication or

certain IO activity.

•

BAT INSERT CHECK mode is a powered up, but low-power halted, state, where the gas gauge resides when

no battery is inserted into the system.