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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 (13 MHz part).
Measurement of Battery, Battery Type and Ambient Temperature
The voltage equivalent of the temperature and battery code on the voltage separator
will be calculated as the difference against a reference voltage of the EGOLD. For
this, the integrated Σ∆ converter in the
EGOLD
of the RX-I base band branch will be
used. Via an analogue multiplexer, either the RX-I base band signal, the battery code
voltage or the ambient temperature voltage can be switched over to the input of the
converter. The 1-Bit data stream of the converter will be subjected to a data reduction
via the DSP circuit so that the measured voltage (for battery and ambient
temperature) will be available at the end as a 10-bit data word.
Measurement of the Battery Voltage
Analogue to the I-branch either the RX-Q base band signal or the battery voltage can
be measured in the Q-branch. Processing in the DSP circuit will be done analogue to
the I-branch. The
EGOLD
will be specified internally at voltage measurement input
BATT+
for an input voltage of 3V...4.5V.
V1.20
Page 37 of 48
ICM MP CCQ GRM
A55/C55_Hitachi
Company Confidential © Copyright Siemens AG
04/03
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