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POWER SUPPLIES
Issue 1
Section 9
MCUK990801G8
Revision 0
– 34 –
Technical Guide
9.3.2 Power-up Sequence
The power-up sequence can be initiated by pressing the power key, or by applying a power source to the EXT_PWR signal
line. 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 determine whether to remain powered-up or not, according to the truth-table shown below. In each case the
active parameters are shaded.
With a hands-free unit connected, 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.
9.4 Power-down
There are two power-down procedures:
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.
Battery Condition
HF
nEXT_PWR
nIGNITION
KBR0
LOGIC_PWR
Mode
OK
X
X
X
1
1
active
LOW
X
>1.2 V
X
1
1
restricted
OK or LOW
no
>1.2 V
X
0
1
charge
OK
yes
>1.2 V
<0.5 V
0
1
active or charge
LOW
yes
>1.2 V
<0.5 V
0
1
restricted or charge
Current Mode
HF
nEXT_PWR
nIGNITION
KBR0
Battery Condition
New Mode
Charge
X
X
X
1
OK
active
Charge
X
1.2 V
X
1
LOW
restricted
Restricted
X
X
X
0
OK
active
Procedure
Description
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.
Current mode
Battery Voltage
HF
nIGNITION
EXTINT
KBR0
nEXT_PWR
power-down
New mode
X
X
X
1
X
<0.5 V
normal
OFF
X
X
X
X
0
X
X
emergency
OFF
X
X
X
X
1
1
<0.5 V
normal
OFF
active
<3.5 V
X
X
1
0
>1.2 V
normal
restricted
active
<3.5 V
no
X
1
1
>1.2 V
normal
charge
active
<3.5 V
yes
>2.5 V
1
1
X
normal
OFF
active
<3.5 V
yes
<0.5 V
1
1
>1.2 V
normal
charge
active
<3.5 V
yes
>2.5 V
1
0
X
normal
OFF
active
X
no
X
1
1
>1.2 V
normal
charge
active
X
yes
<0.5 V
1
1
>1.2 V
normal
charge
active
X
yes
>2.5 V
1
1
X
normal
OFF
active
X
yes
>2.5 V
1
0
>1.2 V
normal
OFF
active
X
X
X
1
0
<0.5 V
normal
OFF
