V1.00 Page 34 of 49 ICM MP CCQ GRM
S55/S57 Company Confidential © Copyright Siemens AG 12/02
6.2 Battery
As a standard battery a LiIon battery with a nominal capacity of 3,7 Volt/700mAh is
used.
6.3 Charging Concept
6.3.1.1 Charging Concept
General
The battery is charged in the unit itself. The hardware and software is designed for
LiIon with 4.2V technology.
Charging is started as soon as the phone is connected to an external charger. If the
phone is not switched on, then charging takes place in the background (the customer
can see this via the “Charge” symbol in the display). During normal use the phone is
being charged (restrictions: see below).
Charging is enabled via a PMOS switch in the phone. This PMOS switch closes the
circuit for the external charger to the battery. The EGOLD+ takes over the control of
this switch depending on the charge level of the battery, whereby a disable function in
the POWER SUPPLY ASIC hardware can override/interrupt the charging in the case
of over voltage of the battery (only for Manganese Chemistry Battery types e.g. NEC).
With the new slim Lumberg IO connector we lose the charger recognition via SB line.
Now we measure the charge current inside the POWER SUPPLY ASIC with a current
monitor.
The charging software is able to charge the battery with an input current within the
range of 350-600mA. If the Charge-FET is switched off, then 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. The temperature sensor will be an NTC resistor
with a nominal resistance of 22kΩ at 25°C. The determination of the temperature is
achieved via a voltage measurement on a voltage divider in which one component is
the NTC. The NTC for the ambient temperature will be on the PCB (26 MHz part).
Charging current
Charging control signal
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