Decoder; Charger - Motorola LX2 plus Service Manual

LX2 plus / advanced and LX4 plus / advanced
3.2

Decoder

LX2 plus:
LX2 plus / advanced:
LX4 plus / advanced:
3.2.1 Power Supply
PCB No. 227.02.xx:
The DC/DC up-Converter IS5 produces the output voltage of 2.85V supplying the digital
section with the help of components L3, D6, C20, C21. The diode D8 protects the con-
verter from too high input voltages or from a battery connected the wrong way round.
C23, C24 decouple the converter from the battery.
The components T1, R3, R7, R11 and C10 are necessary for a stable start behavior of the
controller.
Transistors T3, T4 turn the receiver on and off.
PCB No. 227.01.xx / PCB No. 230.01.xx:
The DC/DC up-Converter IS5 produces the output voltage of 2.4V suppling the digital
section with the help of components L3, D6, C20, C21, R17 and R25. The diode D8 pro-
tects the converter from too high input voltages or from a battery connected the wrong
way round.
3.2.2 Receiver Interface
All signals necessary to control the receiver are routed to the plug ST1. Resistors R14,
R15, R19 und R20 serve as RF decoupling components.
PCB No. 227.02.xx:
High supply voltage 2.85V is decoupled by L1, low supply voltage 1.2V is decoupled by
L2, C17 and C22.
PCB No. 227.01.xx / PCB No. 230.01.xx:
High supply voltage 2.40V is decoupled by L1 and R6, low supply voltage 1.2V is decou-
pled by L2, C17 and C22.
3.2.3 Charger and Programmer Interface, Charging Circuit
There is an asynchronous serial interface allowing data exchange between pager and
charger and programming the pager (data, battery voltage, 0V).
The charging Unit controls the charging procedure of the pager`s battery. Charger and
pager exchange data regarding the charge level via wire P2.
3.2.4 Real-time Clock and Memory
Real-time clock circuit IS1 provides time and date. The clock continues running after re-
moving the battery for a period of appr. 2 days, because it is buffered by Goldcap C2.
PCB No. 227.02.xx:
IS3 and IS4 are non-volatile memory circuits, holding all necessary parameters for a cor-
rect operation of the pager (IS4: RIC addresses, alert key words, activated functions,
Menu prompts, ... IS3: selected settings, received messages, ...).
B2270901 Content is subject to change without notice!
PCB No. 227.02.xx
PCB No. 227.01.xx
PCB No. 230.01.xx
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