Backup Battery; Normal And Extreme Voltages - Nokia RM-555 Service Manual

The battery temperature is estimated by measuring separate battery temperature NTC via the BTEMP line.
This is located on the main PWB, at the place where the phone temperature is closest to the battery
temperature.
Battery connector
The battery connector is a blade connector. It has three blades;
• BSI (Battery size indicator)
• GND (Ground)
• VBAT (Battery voltage)
Charging
This phone is charged through the micro USB connector. The phone supports dedicated, host or hub chargers.
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 BL-4D battery is used.
Voltage
Nominal voltage
Lower extreme voltage
Higher extreme voltage
(fast charging)
Page 6 –10
Figure 64 Battery pin order
Figure 65 Blade battery connector
Table 10 Nominal voltages
Voltage [V]
General Conditions
3.700
3.145
4.230
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System Module and User Interface
Condition
RM-555
Issue 1