User Guide

NPM-10 (3595)
System Module CC Technical Documentation
Page 22 ©2004 Nokia Corporation Confidential Issue 2 03/2004
Power Up and Reset
Power up and reset is controlled by the UEM ASIC. The baseband can be
powered up in following ways:
• Press power button, which means grounding the PWRONX pin of the UEM
• Connect the charger to the charger input
• Supply battery voltage to the battery pin
• RTC Alarm, the RTC has been programmed to give an alarm
After receiving one of the above signals, the UEM counts a 20 ms delay and then enters
its reset mode. The watchdog starts up and, if the battery voltage is greater than Vcoff+,
a 200 ms delay is initiated to allow references, etc., to settle. After this delay elapses, the
VFLASH1 regulator is enabled. Then, 500 us later, VR3, VANA, VIO, and VCORE are
enabled. Finally, the PURX line is held low for 20 ms. This reset, PURX, is fed to the base-
band ASIC UPP; resets are generated for the DSP and the MCU. During this reset phase,
the UEM forces the VCXO regulator on, regardless of the status of the sleep control input
signal to the UEM. All baseband regulators are switched on at the UEM power on, except
for the SIM regulator that is controlled by the MCU. The UEM internal watchdog is
running during the UEM reset state, with the longest watchdog time selected. If the
watchdog expires, the UEM returns to power off state. The UEM watchdog is internally
acknowledged at the rising edge of the PURX signal in order to always give the same
watchdog response time to the MCU.
Power Up - Power Key
When the power on key is pressed, the UEM enters the power up sequence as described
in the Power Up and Reset section. Pressing the power key causes the PWRONX pin on
the UEM to be grounded. The UEM PWRONX signal is not part of the keypad matrix. The
power key is only connected to the UEM. This means that when the power key is pressed,
an interrupt is generated to the UPP that starts the MCU. The MCU then reads the UEM
interrupt register and notices that it is a PWRONX interrupt. The MCU now reads the
status of the PWRONX signal using the UEM control bus, CBUS. If the PWRONX signal
stays low for a specified time, the MCU accepts this as a valid power on state and
continues with the SW initialization of the baseband. If the power on key does not
indicate a valid power on situation, the MCU powers off the baseband.
Power Up - Charger is Connected
In order to be able to detect and start charging in a case where the main battery is fully
discharged (empty) and hence UEM has no supply (NO_SUPPLY mode of UEM), charging
is controlled by START-UP CHARGING circuitry.
Charging thermal shutdown threshold TjsdC+
TjsdC-
140
120
150
130
160
140
°C
VFLASH1 supply voltage input VFLASH1 2.7 2.78 2.88 V
Table 20: Electrical Characteristics (Continued)
Parameter Test Conditions Symbol Min Type Max Units