Power Supply; Battery; Charging Concept - Siemens C75 Service Repair Documentation

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7 Power Supply

7.1 ASIC Mozart / Twigo4
The power supply ASIC will contain the following functions:
• Powerdown-Mode
• Sleep Mode
• Trickle Charge Mode
• Power on Reset
• Digital state machine to control switch on and supervise the uC with a
watchdog
• 17 Voltage regulators
• 2 internal DC/DC converters (Step-up and Step-down converter)
• Low power voltage regulator
• Additional output ports
• Voltage supervision
• Temperature supervision with external and internal sensor
• Battery charge control
• TWI Interface (I
• Bandgap reference
• High performance audio quality
• Audio multiplexer for selection of audio input
• Audio amplifier stereo/mono
• 16 bit Sigma/Delta DAC with Clock recovery and I

7.1.1 Battery

As a standard battery a LiIon battery with a nominal capacity of 780mAh@0.2CA* and GSM
capacity** of min. 750mAh will be provided.
* battery will be discharged with 20% of capacity rate till 2.75V; e.g. R65, 0.2x750mA=150mA
** battery will be discharged with 2A(0.6ms)+0.25A(0.4ms) till 3.2V.

7.1.2 Charging Concept

7.1.2.1 General
The battery is charged in the phone. 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 shall take 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
processor takes over the control of this switch depending on the charge level of the battery,
whereby a disable function in the ASIC hardware can override/interrupt the charging in the
case of over voltage of the battery
Service Repair Documentation
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