V1.0 Page 24 of 38 ICM MP CC ST
A35-A36-A40 Company Confidential 09/01
6. Battery and Charging
6.1 Battery
A NiMH battery with a nominal capacity of 600mAh is used for the Axx series Notes
A temperature sensor (22kΩ at 25°C) is integrated to monitor the battery
temperature.
Battery connector:
6.2 Charging Concept
The battery is charged in the unit itself. The hardware and software is designed for
for NiMH batteries. The battery will be charged as long as the GAIM part of the
EGOLD+ will measure changes in the values of the battery voltages during the
charging process.
There are two ways to charge the battery:
1) Normal charging also called “fast charging”
2) Trickle charging
Normal Charging:
As soon as the phone is connected to an external charger, charging starts.
(The “Charge” symbol in the display shows the charging process).
Charging is enabled via a MOS-FET-Switch(V200). This MOS-FET-Switch activates
the circuit form the external charger to the battery.
A “low” signal at the gate of this transistor is required. To get this “low” the following
conditions must be fulfiled :
a) The CHARGE_UC signal at pin 31 of the ASIC must be “H”
b) The temperature information at pin 2 of the ASIC must be “L” < 55°C
c) The overvoltage detection at pin 22 VDDLP has not to be active < 5,8V
A disable function in the ASIC´s hardware can interrupt charging in case of:
a) A too high temperature >55°C
b) A too high battery voltage >5,8V
For temperature detection, a NTC resistor (22kΩ at 25°) is assembled in the
battery pack. Via the pin 2 of the battery connector and a resistor combination R115,
R116,R117, the EGOLD+ (GAIM L3) is carrying out the measurement.
To get the CHARGE_UC (Miscellaneous E9) signal, the EGOLD+ needs the information
that an external power supply is connected. This is realized by feeding the POWER
signal through the voltage divider R204 and the resistor R202 as a
EXT_POWER_UC to the EGOLD+ (Miscellaneous A2)
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