Power Up And Reset - Nokia NPD-1 Series Troubleshooting - Bb

NPD-1
Troubleshooting — BB

Power Up and Reset

Power up and reset is controlled by the UEM ASIC. The baseband can be powered up in
the following ways:
• By the Power button, which means grounding the PWRONX pin of the
UEM
• By connecting the charger to the charger input
• By the RTC Alarm, when the RTC logic 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 started to allow references and so on to settle. After this delay elapses,
the VFLASH1 regulator is enabled. Then, 500 us later, VR3, VANA, VIO, and VCORE are
enabled. Finally, the Power Up Reset (PURX) line is held low for 20 ms. This reset, PURX is
sent to UPP and resets are generated for the MCU and the DSP. During this reset phase,
the UEM forces the VCTCXO regulator on regardless of the status of the sleep control
input signal to the UEM. The FLSRSTx from the UPP is used to reset the flash during
power up and to put the flash in power down during sleep. All baseband regulators are
switched on at the UEM power on—except for the SIM regulator and Vflash2. Vsim is not
used this moment and Vflahs2 is used for active cover. The UEM internal watchdogs are
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 watchdogs are internally
Page 10
Figure 4: Flashing (continued)
Nokia Corporation
CCS Technical Documentation
FLASH_3
Confidential
CH1 = PURX
CH2 = MBUS
CH3 = FBUSTX
CH4 = FBUSRX
Measure points
Production test pattern
(J396)
Data transfer has
started (Fbus_Rx)
Issue 1 11/2002