Sony CMD-CD5, Service Manual

5

SECTION 2

GENERAL DESCRIPTIONS

2.1 Multi-band :

CMD-CD5 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-CD5 is a phase II, GSM 900 class 4, DCS 1800 class 1 mobile phone.
The nominal maximum output power for GSM 900 is 2W, for DCS 1800 1W.

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 CPU.
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 has reached a voltage level of 3.5V the RTC keeps the time for 10 days.
After the main battery is removed the RTC keeps the time for 10 min.

2.3 Vibra Functionality

The vibrator is a 1.3V device with a vibrating frequency fixed at 120Hz (

±

20%).

A general port pin of the CPU controls the switch mode of the vibration motor. It is powered direct from the battery
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 (4.24V- 4.3V). The charging resumes
when Vbat falls below (4.11V - 4.23V).

Under voltage: When the cell voltage drops below (1.3V - 1.7V) the cell is disconnected for discharging.
Charging is still possible.