Nokia 500 Service Manual page 150

RM-750
System Module
The phone is powered by a 3-pole BL-4U battery S-pack 1100 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 17 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.
Figure 18 Blade battery connector
Charging
This phone is charged through the smaller Nokia standard interface (2.0 mm plug). The wider standard
charger (3.5 mm) can be used together with the CA-44 charger adapter.
Figure 19 Small (right) and wide (left) charger plugs
Charging is controlled by energy management, and external components are needed to protect the baseband
module against EMC, reverse polarity and transient frequency deviation.
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