Nokia RH-44 Series Troubleshooting - Bb page 10

RH-44
Troubleshooting — BB
watchdog expires, the UEM returns to power off state. The UEM watchdogs are internally
acknowledged at the rising edge of the PURX signal in order to always give the same
watchdog response time to the MCU.
The following timing diagram represents UEM start-up sequence from reset to power-on
mode.
Reference signal
PwrOnX
Charger Detection
RTC
UEMRSTX
VFlash1
VIO
VCORE
VANA
VR3
19.2MHz Clk
PURX
32kHz XTAL
Page 10
t1 t2 t3 t4
Figure 5: Power on sequence and timing
Nokia Corporation
CCS Technical Documentation
t1 = 20ms t3 = 500us
t2 = 200ms t4 = 20ms
Confidential Issue 1 04/2003