
Motorola Internal Use
10
P7389i – Circuit Description
•
V3
– Programmed to 2.003V to support the Whitecap, but does support the normal
2.75V logic output from the Whitecap, it originates from GCAP II
Pin B5
and can be
measured on
C909
or
C910
.
•
VSIM1
– Used to support either 3V or 5V SIM cards. Will dynamically be set to 3V
upon power up, but if the card cannot be read then the SIM card is powered down and
an attempt to read the card at 5V is tried. VSIM1 can be measured on
C905
and is
distributed from GCAP II
Pin
C6
(For further information, see SIM Card Operation).
•
VREF
– Programmed as
V2
i.e. 2.775 and provides a reference voltage for the
MAGIC DM IC, distributed from GCAP II
Pin G9
and can be measured on
C919
.
•
-5V
–
Used to drive display and
–10V
–
Used for RF
GSM / DCS selection signals
through
Q160.
Both voltages produced by
V1
through
U903
and
U904
.
•
SR_VCC
–
Power Cut Circuit
- Used to buffer the
SRAM U702
voltage with a built
in soft reset within the unit’s software. The reason for this is to protect the user from
any accidental loss of power up to 0.5 seconds i.e. If the unit is knocked, causing a
slight battery contact bounce, the
SR_VCC
will, to the user, keep the unit running
normally, whilst internally the unit resets itself. During this loss of power the unit
takes it’s power from
RTC
and is originated from
GCAP II
Pin E1
•
V1_SW –
See
Deep Sleep Mode
5)
Once the power source has been selected to power the phone on the
PWR_SW
must
be toggled low. This can be done by pressing the
Power Key
S500
to create
ON_2
,
which is supported by
PWR_SW
(GCAP II
Pin C8
). Alternatively by plugging in an
external fast charger, if a battery is present, then again the
ON_2
line will be pulled
low.