Text preview for : TechDesAcc.pdf part of Ericsson TechDesAcc . Rare and Ancient Equipment Ericsson Mobile Phones ERICSSON EH238 TechDesAcc.pdf
Back to : TechDesAcc.pdf | Home
Technical Description Accessories
Ericsson Handheld Telephone 1341-B
Vehicle Power Adaptor VP2000
Contents
Introduction ___________________________________________ 3
Main Features _________________________________________ 3
Power Supply ____________________________________________ 3
Charging ________________________________________________ 5
Specifications_________________________________________ 6
Connectors and Signals ______________________________ 6
System Connector J1 ______________________________________ 6
Power Connector J2 _______________________________________ 7
Technical Description Accessories: VP2000
2
Technical Description Accessories: VP2000
Introduction
The Vehicle Power Adaptor VP2000 is plugged into the 12 V cigarette lighter
outlet and provides power to the telephone at the same time as it charges the
telephone battery.
The Vehicle Power Adaptor consists of three parts; the plug which contains
the electronics, the coiled cord and the detachable connector part.
Main Features
Power Supply
The logic in the telephone controls the power supply. The current values
needed by the telephone in different situations, for example in standby or in
transmission, are programmed and stored in the telephone.
The VP2000 delivers two current levels only, 700 mA and 30 mA. These lev-
els are pulsed during a 30 seconds period to enable any average level to be
achieved.
Every 30 second period begins with a 700 mA pulse and ends with a 30 mA
pulse. The length of 700 mA pulse decides the average current.
3
Technical Description Accessories: VP2000
Examples:
Standby: 700 mA for 4 seconds gives 4s / 30s x 700 = 93 mA
Transmission: 700 mA for 25 seconds gives 25s / 30s x 700 = 583 mA
The battery of the telephone takes care of the redundant current during the
700 mA part and support with extra current during the 30 mA part. This means
a battery always has to be attached to the phone when it is connected to
the Vehicle Power Adaptor.
Note: To trickle-charge the battery the actual value of the current is set some
mA higher than the current required.
4
Technical Description Accessories: VP2000
Charging
The batteries used are of the type nickel metal hydride, NiMH. There are
four contacts on the battery: plus, minus, T and K. The contact T is used for
the temperature sensor. K is not used.
When the telephone is connected to the charger and switched ON, the battery
condition is analyzed. If charging is decided, 700 mA is delivered constantly.
During the charging the voltage and the temperature increase and follow the
curve as shown in the figure below.
The battery voltage and the temperature are measured every second. A mean
voltage value and a mean temperature value, are calculated every minute.
These minute values are compared according to the following methods: