Charging Concept - Siemens A70 Service Repair Documentation

Company Confidential
Copyright 2005© Siemens AG

9.3 Charging Concept

Charging current
Charging control signal
9.3.1.1 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
depending on the charge level of the battery, whereby a disable function in the
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
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).
TD_Repair_L2.5_A70_A75_R1.0.pdf
EGOLDlite takes over the control of this switch
POWER SUPPLY ASIC
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with a current monitor.
Release 1.0
POWER