Energy management
Battery and charging
BP-5T battery
The phone is powered by a 3-pole BP-5T 1650 mAh battery. The three poles are named VBAT, BSI and GND
where the BSI line is used to recognize the battery capacity. This is done by means of an internal battery pull
down resistor.
Figure 32 Battery pin order
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)
The BSI line is used to recognize the battery capacity by a battery internal pull down resistor.
Charging
The phone can be charged through the micro USB interface.
Charging is controlled by energy management, and external components are needed to protect the baseband
module against EMC, reverse polarity and transient frequency deviation.
Charging a dead battery
It may take up to several minutes before the phone indicates that it is charging if the battery is dead.
Normal and extreme voltages
Energy management is mainly carried out in the EM ASIC (N4200). that contains a number of regulators. In
addition there are also some external regulators.
In the table below normal and extreme voltages are shown when a BP-5T battery is used.
Table 8 Nominal voltages
Voltage
Voltage [V]
Condition
General Conditions
Nominal voltage
3.700
Lower extreme voltage
3.1
RM-824; RM-825; RM-826
System Module
Issue 2
NOKIA INTERNAL USE ONLY
Page 6 – 9
Copyright © 2012 Nokia. All rights reserved.
