CCS Technical Documentation
System Module and User Interface
NSB-9
Issue 1 04/03
Nokia Corporation
Page 35
Table 27: Pin numbering of Battery Pack
Figure 8: Battery Pack contents
The BSI fixed resistor value indicates type and default capacity of a battery. NTC-resistor
BTEMP measures the battery temperature.
Temperature and capacity information are needed for charge control. These resistors are
connected to BSI and BTEMP pins of battery connector. Phone has 100 k
Ω
pull-up resis-
tors for these lines so that they can be read by A/D inputs in the phone.
Backup Battery
Backup battery is used in case when main battery is either removed or discharged.
Backup battery is used to keep real-time clock (RTC) running for minimum of 30 minutes.
Rechargeable backup battery (capacitor type) is connected between UEM VBACK and
GND. In UEM backup battery charging high limit is set to 3.2V. The cut-off limit voltage
(VBUCoff-) for backup battery is 2.0V. Backup battery charging is controlled by MCU by
writing into UEM register. Battery is not charged during power off.
Table 28: Back-up circuity
Signal name
Pin number
Function
VBAT
1
Positive battery terminal
BSI
2
Battery capacity measurement (fixed resistor inside the battery pack)
BTEMP
3
Battery temperature measurement (measured by ntc resistor inside pack)
GND
4
Negative/common battery terminal
Parameter
Test conditions
Symbol
Min
Typ
Max
Units
Back-up battery voltage
VBACK
2.43
3.3
V
Back-up battery cut-off limit
V_BU
COFF+
V_BU
COFF-
2.04
1.94
2.10
2.0
2.16
2.06
V
V
Charging voltage (VBAT
≥
3.4V)
VBU
3.1
3.2
3.3
V
Charging current
I
LIMVBU
150
500
m
A
1 (+)
2(BSI)
3(BTEMP)
4(GND)