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9.3.2 Power-up Sequence
The power-up sequence can be initiated by pressing the power key or by the presence of an external power source
on the signal EXT_PWR. Both enable the linear regulators and the CPU becomes active. The CPU must then
check the battery condition; if the phone is not required to power-down or sleep immediately, the result must be OK
or LOW, the CPU then checks to see if a hands-free unit is connected by polling the nHF_SENSE signal, LOW
when HF is connected.
Now the CPU can make the decision whether to remain powered-up or not according to the truth-table below. In
each case the active parameters are shaded.
Battery
condition
HF
EXT_PWR_SENSE
nIGNITION
KBR0
STAY_ALIVE
Mode
OK
X
X
X
1
1
active
LOW
X
>1.2V
X
1
1
restricted
OK or LOW
no
>1.2V
X
0
1
charge
OK
yes
>1.2V
<0.5V
0
1
active or charge
LOW
yes
>1.2V
<0.5V
0
1
restricted or charge
With a hands-free, the phone can be configured via the MMI to power-up and down with transitions of the vehicle
ignition. These are sensed by the CPU on nIGNITION, LOW when the ignition is on.
Any other state than those in the table will cause the phone to deactivate the PSU by setting STAY_ALIVE LOW.
While the CPU is active, it must monitor the battery condition and accessory connectivity and change state
accordingly.
Currentmode
HF
EXT_PWR_SENSE
nIGNITION
KBR0
Battery
condition
New mode
charge
X
X
X
1
OK
active
charge
X
1.2V
X
1
LOW
restricted
restricted
X
X
X
0
OK
active
9.3.3
Power-down
There are two power-down procedures;
Normal power-down
In this case, the software has full control over the power-down procedure. Calls can
be terminated gracefully etc. In some cases the PSU is not deactivated but there is a
change of operating mode
Emergency power-down
This situation is caused by battery removal and is flagged by EXTINT. In this case the
CPU only has time to perform a subset of the normal procedure. The priority is to
prevent corruption of SIM data
The truth-table for the power state transitions are shown below, the cause of a transition is shaded. In some cases
the phone does not power down completely but may enter a state of reduced functionality e.g. from active to
charge mode.
When the new mode is OFF or sleep, the CPU will set STAY_ALIVE LOW.
MCUK971001G8
Section 9
Issue 1
Technical Guide
9 - 3
Revision 0
POWER SUPPLIES