BQ29330 Datasheet, PDF (15/26 Pages) Texas Instruments – 2-,3-,AND 4-CELL LITHIUM-ION OR LITHIUM-POLYMER BATTERY PROTECTION AFE

bq29330
www.ti.com
SLUS673A – SEPTEMBER 2005 – REVISED DECEMBER 2005
FUNCTIONAL DESCRIPTION (continued)
Once the watchdog has been started during this wake-up period, it monitors the host for an oscillation stop
condition which is defined as a period of t_WDWT where no clock input is received. If an oscillator stop condition is
identified, then the watchdog turns the CHG, DSG, and ZVCHG FETs off. The bq29330 then activates the XRST
output in an attempt to reset the host.
If the host clock oscillation is started after the reset, the bq29330 still has the WDF flag set until it is cleared. See
the LTCLR section for further details on clearing the fault flags.
During Sleep mode, the watchdog function is not disabled.
WDRST = L
REG Output
RST Output
WDI Input
XALERT
FET Control
Access by Host
t_{WDTINT (500 ms)}
t_RST
t_{WDTINT (500 ms)}
CHG, DSG, and
ZVCHG = OFF
WDRST = H
REG Output
RST Output
WDI Input
XALERT
FET Control
Access by Host
t_{WDTINT (500 ms)}
Twice
t_{WDTINT (500 ms)}
t_RST
t_RST
t_RST
t_{WDTINT (500 ms)}
CHG, DSG, and
ZVCHG = OFF
Figure 3. Watchdog Timing Chart – WDI Fault at Start-up
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