Power Key And System Power-Up - Nokia N900 Service Manual

RX-51
System Module
Voltage
Battery voltage
Cutoff voltage (SW)
Cutoff voltage (HW)
Backup battery voltage

Power key and system power-up

After inserting the main battery, regulators started by HW are enabled. SW checks if there is some reason to
keep the power on. If not, the system is set to power off state by watchdog.
Power-up can be caused by the following reasons:
• Power key is pressed
• Charger is connected
• RTC alarm occurs
• MBUS wakeup
APE engine is the master that handles the device start-up. After the APE side is up it can release the CMT side
from reset state.
Issue 1
Table 14 Nominal voltages
Voltage [V]
4.2
3.2
2.7
3.2
Figure 50 APE and CMT control signals and interfaces
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Notes
Maximum voltage
EM SW controlled
Gaia EM ASIC controlled
Typical voltage.
Capacity 15uAh.
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