BQ27425-G2_14 Datasheet, PDF (23/35 Pages) Texas Instruments – System-Side Impedance Track™ Fuel Gauge With Integrated Sense Resistor

bq27425-G2
www.ti.com
SLUSB23A – OCTOBER 2012 – REVISED FEBRUARY 2013
OPERATING MODES
The bq27425 has different operating modes: POR, INITIALIZATION, NORMAL, CONFIG UPDATE, SLEEP, and
HIBERNATE. Upon power up from OFF or SHUTDOWN, a Power On Reset (POR) occurs and the fuel gauge
begins INITIALIZATION. In NORMAL mode, the bq27425 is fully powered and can execute any allowable task.
Configuration data in RAM and NVM can be updated by the host using the CONFIG UPDATE mode. In SLEEP
mode the fuel gauge turns off the high frequency oscillator clock to enter a reduced-power state, periodically
taking measurements and performing calculations. In HIBERNATE mode the fuel gauge is in a very low power
state, but can be woken up by communication or certain I/O activity.
In SHUTDOWN mode, the LDO is disabled so internal power and all volatile data is lost. Since no gauging
occurs in SHUTDOWN mode, additional gauging error can be introduced if the system has significant battery
charge/discharge activity prior to re-INITIALIZATION.
Exit From HIBERNATE
V _CELL < POR threshold
OFF
REGIN pin = OFF,
V_CC pin = OFF
Entry to SHUTDOWN
REGIN pin > V_REGIN min
SHUTDOWN
REGIN pin > V_REGIN min,
V_CC pin = OFF
CE pin set LOW
(from any mode)
Exit From SHUTDOWN
CE pin raised HI
Power On Reset [POR]
Copy configuration ROM
defaults to RAM data.
Set Flags[ITPOR] = 1.
via RESET
subcommand
(from any mode)
Exit from CONFIG UPDATE
Flags [CFGUPMODE] = 0 AND [ITPOR] = 0
(via SOFT_RESET or a 240 second timeout)
INITIALIZATION
CONFIG UPDATE
Flags
[BAT _ DET ] = 0
Initialize algorithm and data.
Check for battery ins.ertion.
(No gauging in this mode.)
I _CC = Normal
Host can change RAM and
NVM based data blocks.
(No gauging in this mode.)
Entry to CONFIG UPDATE
Flags [CFGUPMODE] = 1
Entry to NORMAL
Flags [ BAT _ DET ] = 1
Exit From NORMAL
Flags [BAT _ DET ] = 0
(via SET_CFGUPDATE
subcommand)
Exit From HIBERNATE
Communication Activity
OR
bq27425 clears CONTROL_STATUS
[HIBERNATE ] = 0
Recommend Host also set Control
Status [HIBERNATE ] = 0
NORMAL
Fuel gauging and data
updated every 1s
ICC = Normal
Exit From SLEEP
Op Config [SLEEP ] = 0
OR
| AverageCurrent ( ) | > Sleep Current
OR
Current is Detected above I WAKE
HIBERNATE
Disable all subcircuits
except GPIO .
I CC = Hibernate
Wakeup From HIBERNATE
Communication to gauge
AND
Comm address is NOT for bq27425
Entry to SLEEP
Op Config [SLEEP ] = 1
AND
| AverageCurrent ( ) | < Sleep Current
Exit From WAIT _HIBERNATE
Host must set CONTROL_STATUS
[HIBERNATE ] = 0
AND
VCELL > Hibernate Voltage
SLEEP
Fuel gauging and data
updated every 20 seconds
I _CC = Sleep
Exit From WAIT _ HIBERNATE
Cell relaxed
AND
| AverageCurrent () | < Hibernate
Current
OR
Cell relaxed
AND
V CELL < Hibernate Voltage
WAIT _HIBERNATE
Fuel gauging and data
updated every 20 seconds
I CC = Sleep
Entry to System Shutdown
Host has set CONTROL_STATUS
[HIBERNATE ] = 1
OR
VCELL < Hibernate Voltage
System Shutdown
Figure 2. Power Mode Diagram
Copyright © 2012–2013, Texas Instruments Incorporated
Product Folder Links: bq27425-G2
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