User Guide

Charging is controlled by energy management, and external components are needed to protect the baseband
module against EMC, reverse polarity and transient frequency deviation.
Backup battery
When the main battery is not attached EM ASIC (N2200) goes in backup mode using back-up battery that
supplies voltage to RTC in EM ASIC (N2200).
Normal and extreme voltages
Energy management is mainly carried out in the two Application Specific Integrated Circuits (ASICs) BETTY
and AVILMA. These two circuits contains a number of regulators. In addition there are some external
regulators too.
In the table below normal and extreme voltages are shown when a BP-4L battery is used.
Table 14 Nominal voltages
Voltage Voltage [V] Condition
General Conditions
Nominal voltage 3.700
Lower extreme voltage 3.145
Higher extreme voltage
4.230(fast charging)
HW Shutdown Voltages
Vmstr+ 2.1 ± 0.1 Off to on
Vmstr- 1.9 ± 0.1 On to off
SW Shutdown Voltages
Sw shutdown 3.1 In call
Sw shutdown 3.2 In idle
Min Operating Voltage
Vcoff+ 2.9 ± 0.1 Off to on
Vcoff- 2.6 ± 0.1 On to off
Power key and system power-up
When the battery is placed in the phone the power key circuits are energized. When the power key is pressed,
the system boots up (if an adequate battery voltage is present).
Power down can be initiated by pressing the power key again (the system is powered down with the aid of
SW). The power key is connected to EM ASIC N2200 (AVILMA) via PWRONX signal.
Modes of operation
Mode Description
NO_SUPPLY (dead) mode means that the main battery is not present or its voltage is too low (below
N2200 AVILMA master reset threshold) and that the back-up battery voltage is too low.
BACK_UP The main battery is not present or its voltage is too low but back-up battery voltage is
adequate and the 32 kHz oscillator is running (RTC is on).
RM-437; RM-449; RM-450
System Module and User Interface
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