http://cxema.ru
Signal
CPU I/O
Description
LUA
I
External interrupt to the CPU. The voltage detector output goes LOW when
the battery voltage drops below 3.6V. If the phone is on, this signal forces
the PSU off and the interrupt initiates an emergency power down procedure.
If the phone is off, a LOW on this signal will lock the PSU off. EXTINT can
override all signals except EXT_PWR
LOGIC_PWR
O
Signal generated by the CPU to hold the PSU on. Active high
DC_OUT
NC
Chip select to the 3.0 and 3.4V regulators. Active low
SIM_PWR_CNT
O
Output from the CPU to enable the SIM 5.0V supply. Active high DEV
nIGNITION
I
Vehicle ignition. When the vehicle ignition is on, this signal is LOW. This is
sensed by the CPU as an analogue voltage
9.3
Power-up
The power-up procedure has two phases: There is an initial check to see if the battery is in good condition. If
successful, the second phase determines the source of the power-up request, key press, external power,
accessory etc. and acts accordingly.
The phone can be defined as powered-on whenever the linear regulators are active. It is not always obvious to the
user that the phone is powered-on as it may be in one of four modes.
Sleep
In this mode the CPU has been prevented from deactivating the linear regulators by EXT_PWR.
There is no CPU activity
Charge
The CPU is alive but may
only
perform battery charging functions and monitor the power key.
Restricted
LEDs light, beeps, can charge battery etc. but it is
not
permitted to use the radio.
Active
The mobile is fully functional; LEDs light, beeps, search for network etc.
9.3.1 Battery Condition
The CPU must check the battery condition before deciding to power-up. The CPU can measure battery voltage and
temperature. If the temperature measurement is invalid, giving a ridiculous temperature reading; a non-standard
battery has been fitted, the battery is missing or the whole phone is operating far outside its specified temperature
range. In any of these cases the phone must not power up. The CPU will regularly monitor the battery condition
while the phone is on.
If EXT_PWR is present the regulators will be forced on and the CPU will not be able to deactivate them. If the CPU
wants to power-down, all it can do is to enter sleep mode.
Battery Voltage (V)
Temp. reading
EXT_PWR_SENSE
Result
X (don’t care)
invalid
0.5V
Power-down (battery fault)
X
invalid
1.2V
Sleep (battery fault)
<4.0
X
<0.5V
Power-down (low battery)
<4.0
valid
1.2V
LOW
>4.0
valid
X
OK
Issue 1
Section 9
MCUK980101G8
Revision 0
9 - 2
Technical Guide
POWER SUPPLIES
