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SLUSCM0A – JUNE 2017 – REVISED SEPTEMBER 2018

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Feature Description (continued)

8.3.3.3 FULLSLEEP Mode

FULLSLEEP mode turns off the high-frequency oscillator and performs AverageCurrent(), Voltage(), and

Temperature() less frequently, which results in power consumption that is lower than that of the SLEEP mode.

FULLSLEEP mode can be enabled by two methods:

•

Setting the [FULLSLEEP] bit in the Control Status register using the FULL_SLEEP subcommand and Full

Sleep Wait Time (FS Wait) in data flash is set as 0.

•

Setting the Full Sleep Wait Time (FS Wait) in data flash to a number larger than 0. This method is disabled

when the FS Wait is set as 0.

FULLSLEEP mode is entered automatically when it is enabled by one of the methods above. When the first

method is used, the gauge enters the FULLSLEEP mode when the fuel gauge is in SLEEP mode. When the

second method is used, the FULLSLEEP mode is entered when the fuel gauge is in SLEEP mode and the timer

counts down to 0.

The fuel gauge exits the FULLSLEEP mode when there is any communication activity. Therefore, the execution

of SET_FULLSLEEP sets the [FULLSLEEP] bit. The FULLSLEEP mode can be verified by measuring the

current consumption of the gauge.

During FULLSLEEP 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 if any entry condition is broken, specifically when either:

•

AverageCurrent() rises above Sleep Current or

•

While in FULLSLEEP mode, the fuel gauge can suspend serial communications by as much as 4 ms by holding

the comm line(s) low. This delay is necessary to correctly process host communication, because the fuel gauge

processor is mostly halted in SLEEP mode.

8.3.3.4 SHUTDOWN Mode

In SHUTDOWN mode, the gauge and protector are completely shutdown. The device automatically enters

SHUTDOWN mode when the following conditions are satisfied:

•

|Current()| < SleepCurrent

•

|Voltage()| < Shutdown V for a period of V Shut Delay

•

Device is in SLEEP or FULLSLEEP mode.

The device can also be instructed to enter SHUTDOWN mode by sending the SET_SHUTDOWN command.

Once received, the fuel gauge sets the CONTROL_STATUS[SHUTDWN] bit and initiates the shutdown

sequence, which opens both the charge and discharge FETs and waits for charger removal.

8.3.4 Li-Ion Battery Protector Description

The battery protector controls two external high-side N-channel FETs in a back-to-back configuration for battery

protection. The protector uses two voltage doublers to drive the CHG and DSG FETs on.

8.3.4.1 High-Side NFET Charge and Discharge FET Drive

These FETs are automatically turned off by the protector based on the detected hardware protection faults or by

the fuel gauge based on detected firmware protection faults. This enables the gauge to be configured with

effectively two levels of safety: the first level employing conservative protection settings to keep the cell within a

safe operating area and the second level set to act as a fail-safe measure to prevent cell damage. Once the

protection fault(s) is deemed to be cleared, the protector or fuel gauge will re-enable the applicable FET(s).

Additionally, the FET drivers can be manually tested at production using the Test(0x74/0x75) extended command

if needed.