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TD_Repair_L2.5_A70_A75_R1.0.pdf Release
1.0
Measurement of Battery, Battery Type and Ambient Temperature
For the conversion of signals like battery voltage, battery type, temperature, EGOLDlite
provides identical measurement interfaces. Measurement circuit is consisting of external
sensing components and integrated analog multiplexers and switches. Through
corresponding switch settings, the measured signal is passed to input of ADC. 12-bit
conversion results are readout by µc and used for charging control.
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
is able to charge the battery at voltages below 3.2V without any
support from the charge SW. The current will by measured indirectly via the voltage drop
over a shunt resistor and linearly regulated inside the
POWER SUPPLY ASIC
. The current
level during trickle charge for 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
POWER SUPPLY ASIC
will switch on the phone automatically and normal charging will be
initiated by software (note the restrictions on this item as stated below).
Normal Charging
For battery voltages above 3.2 Volt and normal ambient temperature between 5 and 40°C the
battery can be charged with a charge current up to 1C*. This charging mode is SW controlled
and starts if an accessory (charger) is detected with a supply voltage above 6.4 Volt by the
POWER SUPPLY ASIC
. The level of charge current is limited/controlled by the accessory or
charger.
