NSW-5
System Module UT5U
PAMS Technical Documentation
Page 23
Issue 1 10/00
Nokia Mobile Phones Ltd.
Uncontrolled Power Down
Power down
when watchdog expires
If the SW fails to update the watchdog, the watchdog will eventually ex-
pire and CCONT cuts all the supply voltages from the phone.
Power down with Battery disconnected
When battery is disconnected, immediate and totally uncontrolled power–
down happens. Therefore a power off procedure in this case can not be
described. One possible risk is that if the MCU is writing something to
Flash exactly at the same moment, the memory contents may be cor-
rupted.
Battery disconnected when charger is connected
From hardware point of view the phone could otherwise continue func-
tioning normally, but if the charger voltage is higher than the maximum
allowed battery voltage, this can damage the RF parts. Therefore, there
must be hardware protection against this in CHAPS.
If the user presses the PWR–key, the phone can wake up to detect that
the battery is not present (no BTYPE and /or BTEMP). After that the
phone either turns itself off or goes to low current mode (can be decided
by MCU SW).
This state does not harm the phone. The phone can not be used only
from the charger without the battery.
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