Three-Wire Charging; Watchdog - Nokia NSW-5 Series Service Manual

NSW-5
System Module UT5U
Both the PWMOUT frequency is selected and the pulse width controlled
by the MCU which writes these values to CCONT.
Three–wire charging
With 3–wire charging the charger provides adjustable output current, and
the charging is controlled by the PWMOUT signal from CCONT to char-
ger, with the bottom connector signal. The PWMOUT signal frequency
set is 32 Hz, and the charger output voltage is controlled by adjusting the
PWMOUT signal pulse width. The charger switch in CHAPS is constantly
on in this case.

Watchdog

BATTERY
CCONT
32 kHz
Both MAD and CCONT include a watchdog, and both use the 32 kHz
sleep clock. The watchdog in thw MAD is the primary one, called SW–
watchdog. MCU has to update it regularly. If it is not updated, logic inside
MAD gives reset to MAD. After the reset the MCU can read an internal
status bit to see the reason for reset, whether it was from the MAD or
CCONT. The SW–watchdog delay can be set between 0 and 63 seconds
at 250 millisecond steps; and after power–up the default value is the max.
time.
MAD must reset CCONT watchdog regularly. CCONT watchdog time can
be set through SIO between 0 and 63 seconds at 1 second steps. After
power–up the default value is 32 seconds. If watchdog elapses, CCONT
will cut off all supply voltages.
After total cut–off the phone can be re–started through any normal pow-
er–up procedure.
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VCXO
MAD
VR1 MCU
VR6
VBB
LOGIC
SLCLK
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PAMS Technical Documentation
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