V1.0 Page 26 of 46 ICM MP CCQ ST
C45, M50 AND MT50 Company Confidential © Copyright Siemens AG 05/02
5.3 Battery and Charging
5.3.1 Battery
A Li-Ion battery with a nominal capacity of 840mAh is used for the S/ME45 series
and a NiMH battery with a nominal capacity of 550mAh for the C45. M50 and MT50
are delivered out with a Li-Ion battery of 650 mAh. A temperature sensor
(22kΩ at 25°C) is integrated to monitor the battery temperature.
Battery connector:
5.3.2 Charging Concept
The battery is charged in the unit itself. The hardware and software is designed for
Li-Ion or NiMH with 4.2V technology.
The battery will be charged as long as the GAIM part of the EGOLD+ measures
changes in the values of the battery voltages during the charging process.
There are two ways to charge the battery:
Normal charging also called “fast charging”
Trickle charging
Normal Charging
As soon as the phone is connected to an external charger, charging starts. The
customer can see this via the “Charge” symbol in the display
Charging is enabled via a FET-Switch (V342) in the phone. This FET-Switch activates
the circuit form the external charger to the battery. The EGOLD+ takes over the
steering of this switch depending on the charge level of the battery, whereby a
disable function in the ASIC (D361) hardware can override/interrupt the charging in
the case of overvoltage of the battery (only in case of NEC batteries).
The charging software is able to charge the battery with an input current within the
range of 350-600mA. If the FET-Switch is switched off, no charging current will flow
into the battery (exception is trickle charging, see below).
For controlling the charging process it is necessary to measure the ambient (phone)
temperature and the battery voltage.
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