Sony CMD-Z28 service manual Section General Descriptions

SECTION 2

GENERAL DESCRIPTIONS

2-1 Multi-band :

CMD-Z28 support E-GSM 900 and DCS 1800 multi-band functionality.

Because the usage of multi-band depends on network capabilities, the phone is able to operate as a single band mobile in GSM 900 as well as in DCS 1800; In addition, it supports the extra functionality required for multi-band mobile stations: Inter-band/ “seamless” hand-over, channel assignment, cell selection and re-selection, all between both bands within a Public Land Mobile Network.

The manual and automatic PLMN selection in both bands is given.

The user does not need any special action to use the multi-band functionality of the phone.

Users are able to manually roam between PLMN’s operating in GSM 900 and DCS 1800 bands.

The CMD-Z28 is a phase II, GSM 900 class 4, DCS 1800 class 1 mobile phone.

The nominal maximum output power for GSM 900 is 2 W, for DCS 1800 1 W.

2-2 Real Time Clock (RTC):

The real time clock is integrated into the phone.

When the mobile is switched on the RTC is powered via the CPP.

When the phone is powered down, the RTC is powered from the main battery via it’s own low quiescent current regulator. When the main battery is low or removed, a back-up battery keeps the clock alive.

After the main battery is removed the RTC keeps the time for 20 days (ability value).

2-3 Vibra Functionality

The vibrator is a 1.3 V device.

A general port pin of the SC1 controls the switch mode of the vibration motor. It is powered through regulator by an interface control unit. If the mobile is in the phase of switching on or off the vibrator is off at all times.

2-4 Battery Safety

The battery pack contains a safety circuitry. The charging circuitry and the safety circuitry together guarantee a double fail-safe battery pack. This means that each component can be either short or open and still all the safety requirements will not be violated.

The safety concept protects against:

Over voltage: The charging is stopped when Battery Voltage (Vbat) reaches (4.24 V- 4.3 V). The charging resumes when Vbat falls below (4.06 V – 4.15 V).

Under voltage: When the cell voltage drops below (2.5 V – 2.7 V) the cell is disconnected for discharging. Charging is still possible.

2-5 Battery Capacity:

Standard Battery	620 mAh typical	Li-ion QN-Z5BPS
Extended Battery	1000 mAh typical	Li-ion QN-Z5BPE (TBD)

The phone can be charged even during making phone calls.

However, the shortest charging time will be reached when the phone is switched off.

As the charging circuit is integrated in the battery pack, the phone cannot be powered up by the charger without the battery pack being attached.

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