Pda Power Management Principle - Nokia 9000i Service Manual

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Technical Documentation

PDA power management principle.

Operating voltage is always ON on the PDA module when battery is
connected and charge level on the battery is above PDA power supply
limit (HW cutt–off). When battery is connected voltage must rise over
'PDA HW limit cancel voltage' to start CPU power–up. Power consumption
reduction is achieved by stopping clocks from the system (stable state
power consumption in CMOS logic is really small).
From CMT point of view PDA module have only two states PDA_ON and
PDA_SUSPEND illustrated in figure 3. When PDA is in PDA_SUSPEND
state it takes about 500 ms (max) Note 1. to wake it up. During the
wakeup period all messages from CMT are discarded. When PDA is in
PDA_ON it wakes up immediately (max few microseconds) and messages
are not discarded. CMT is never able to be ON when PDA is not able to
wakeup because CMT is switched OFF before PDA when battery level is
falling. See Figure 5 that depicts battery charge levels and its effects to
PDA and CMT modules.
Note 1. On A–3 CPU version startup time in low temperatures is up to 20s
PDA software
Figure 3.
The PDA knows whether CMT is on or off by monitoring VL1. It gets
information about battery level by asking for battery level from the CMT.
The PDA is able to switch CMT to the CMT_PDA_REQUEST_SERVICE
state.
Original, 08/96
PDA_ON
PDA_SUSPEND
PDA power states from CMT point of view.
RAE/RAK–1N
PDA Hardware
Message from CMT,
CMT power on or other
PDA activity
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