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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
specified internally at voltage measurement input
Timing of the Battery Voltage Measurement
Unless the battery is charging, the measurement is made in the TX time slot. During charging it will be
done after the TX time slot. At the same time, either the battery temperature (in the I-branch) and the
battery voltage (in the Q-branch) or the ambient temperature in the I-branch can be measured (the
possibility of measurement in the Q-branch, the analogue evaluation of the battery coding, is used for
HW-Coding). Other combinations are not possible. For the time of the measurement the multiplexer in
the EGAIM must be programmed to the corresponding measurement.
Recognition of the Battery Type
The battery code is a resistor with a resistance depending on the manufacturer.
Charging Characteristic of Lithium-Ion Cells
LiIon batteries are charged with a U/I characteristic, i.e. the charging current is regulated in relation to
the battery voltage until a minimal charging current has been achieved. The maximum charging current
is approx. 600mA, minimum about 100mA. The battery voltage may not exceed 4.2V ±50mV average.
During the charging pulse current the voltage may reach 4.3V. The temperature range in which
charging of the phone may be started ranges from 5...40°C, and the temperature at which charging
takes place is from 0...45°C. Outside this range no charging takes place, the battery only supplies
current.
Trickle Charging
The
POWER SUPPLY ASIC
from the charge SW. The current will by measured indirectly via the voltage drop over a shunt resistor
and linearly regulated inside the
voltages <2.8V is in a range of 20-50mA and in a range of 50-100mA for voltages up to 3.75V. To limit
the power dissipation of the dual charge FET the trickle charging is stopped in case the output voltage
of the charger exceeds 10 Volt. The maximum trickle time is limited to 1 hour. As soon as the battery
voltage reaches 3.2 V the
charging will be initiated by software (note the restrictions on this item as stated below).
V 1.10
A52/A55/C55 IFX
is able to charge the battery at voltages below 3.2V without any support
POWER SUPPLY
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Page 35of 45
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BATT+
for an input voltage of 3V...4.5V.
ASIC. The current level during trickle charge for
will switch on the phone automatically and normal
EGOLD
will be
ICM MP CCQ GRM
08/03
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