BQ27350 Datasheet, PDF (24/33 Pages) Texas Instruments – Single Cell Li-Ion Battery Manager With Impedance Track Fuel Gauge Technology

bq27350
Single Cell Li-Ion Battery Manager
With Impedance Track Fuel Gauge Technology
SLUS754 – MARCH 2007
www.ti.com
5.6.3 HIBERNATE MODE
To enter HIBERNATE mode, the [HIBERNATE] bit of PackConfiguration( ) needs to be set when the
device enters SLEEP mode. The HIBERNATE mode is exited if (1) communication is detected, (2) a
device reset occurs, or (3) if current through R_SENSE is above I_WAKE. If the Pack Configuration
[HIBERNATE] bit is cleared, the bq27350 will not enter HIBERNATE mode. Upon exiting HIBERNATE
mode, the device is returned to NORMAL mode.
5.6.4 SHUTDOWN MODE
SHUTDOWN mode requires the use of an external LDO with an enable feature (active low). To enter
SHUTDOWN, the PackConfiguration( ) [SHUTDOWN] bit needs to be set when the bq27350 enters
HIBERNATE. A charger must not be present and the DSG FET of protector must be turned OFF. If the
[SHUTDOWN] bit of PackConfiguration( ) is set, the bq27350 raise its SE pin high on entry into
HIBERNATE. This action, in conjunction with the deactivation of the DSG FET (low-side protector
implementation), shuts down the LDO and, hence, the bq27350. The LDO recovers when a charger is
applied for more than 2s.
5.7 POWER CONTROL
5.7.1 RESET FUNCTIONS
When the bq27350 detects either a hardware or software reset (MRST pin driven low or the [RESET] bit
of Control( ) initiated, respectively), it determines the type of reset and increments the corresponding
counter. This information is accessible by issuing the command Control( ) function with the RESET_DATA
subcommand.
As shown in Figure 5-2 if a partial reset was detected, a RAM checksum is generated and compared
against the previously stored checksum. If the checksum values do not match, the RAM is reinitialized (a
“Full Reset”). The stored checksum is updated every time RAM is altered.
DEVICE RESET
Generate Active
RAM checksum
value
Stored
checksum
NORMAL
OPERATION
NO
Do the Checksum
Values Match?
YES
Active RAM
NO
changed ?
YES
Store
checksum
Generate New
checksum value
Re-initialize all
RAM
Figure 5-2. Partial Reset Flow Diagram
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FUNCTIONAL DESCRIPTION
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