BQ27520-G4 Datasheet, PDF (16/34 Pages) Texas Instruments – System-Side Impedance Track Fuel Gauge

bq27520-G4
SLUSB20B – NOVEMBER 2012 – REVISED DECEMBER 2015
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Device Functional Modes (continued)
8.4.2 SLEEP+ Mode
Compared to the SLEEP mode, SLEEP+ mode has the high-frequency oscillator in operation. The
communication delay could be eliminated. The SLEEP+ mode is entered automatically if the feature is enabled
(CONTROL_STATUS [SNOOZE] = 1) and AverageCurrent() is below the programmable level Sleep Current.
During SLEEP+ mode, the fuel gauge periodically takes data measurements and updates its data set. However,
a majority of its time is spent in an idle condition.
The fuel gauge exits SLEEP+ mode if any entry condition is broken, specifically when:
• Any communication activity with the gauge, or
• AverageCurrent() rises above Sleep Current , or
• A current in excess of I_WAKE through R_SENSE is detected.
8.4.3 HIBERNATE Mode
HIBERNATE mode should be used when the system equipment needs to enter a low-power state, and minimal
gauge power consumption is required. This mode is ideal when system equipment is set to its own HIBERNATE,
SHUTDOWN, or OFF mode.
Before the fuel gauge can enter HIBERNATE mode, the system must set the CONTROL_STATUS
[HIBERNATE] bit. The gauge waits to enter HIBERNATE mode until it has taken a valid OCV measurement and
the magnitude of the average cell current has fallen below Hibernate Current. The gauge can also enter
HIBERNATE mode if the cell voltage falls below Hibernate Voltage and a valid OCV measurement has been
taken. The gauge remains in HIBERNATE mode until the system issues a direct I²C command to the gauge or a
POR occurs. Any I²C communication that is not directed to the gauge does not wake the gauge.
It is the responsibility of the system to wake the fuel gauge after it has gone into HIBERNATE mode. After
waking, the gauge can proceed with the initialization of the battery information (OCV, profile selection, and so
forth).
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