EN 165
3139 785 31532
9.
Circuit- and IC description
9.2. Front Board (Panel – D Key)
9.2.1. General
This board consists of the following parts:
•
μ
P driver for the FTD
•
Frontend (Audio & Video)
•
VFD Heater voltage Generator
9.2.2.
μ
P (IC 7103 : TMP86CM74AFG)
The core element of the Front (D Key) board is the
μ
P [7103].
It runs on a 5V supply & a clock frequency of 16MHz, and is
responsible for the following functions:
•
Interface with the Slave
μ
P on the Analog board via I
2
C
bus
•
Driver for the FTD display [1203 : HUV-08SS65T]
9.2.3. VFD Heater Voltage Generator
Pin 12 of
μ
P [7103] provides the necessary sine wave signal
out for transistor [7106, 7108 & 7109] to generate the 50%
duty-cycle 48KHz AC square-wave signal for the
fi
lament of
the
FTD.
9.3. Analog
Board
9.3.1. General
The Analog board consists of the following parts:
•
Slave
μ
P
•
Fan Control
•
Simple Power Supply
•
Tuner
Frontend
•
Audio
ADC/DAC
9.3.2. Slave
μ
P (IC 7108 : TMP87CH74F)
The
slave
μ
P which run on a 5V supply and is responsible for
the
following
functions:
•
Interface with the Chrysalis chip on the Digital Board via
I
2
C interface, where it functions in the slave-mode
•
Evaluation of the keyboard matrix (network of resistors)
on the Front board via pin 32 and 33.
•
Decoding the remote control commands from the infra-red
receiver on the Front board via pin 22.
•
Activation and control of the FTD display on the Front
board (with the help of 7103 as driver) via I
2
C bus
•
Timer Wake-up activation
•
Fan control via transistors 7104 and 7105
It runs on two clock frequencies namely:
•
8MHz for normal operation
•
32.768KHz for the real time clock
9.3.3. Timer Wake-up activation
During the Standby mode, the slave
μ
P provides a wakeup
call (STBY-line switches to high) to the PSU Board switching
on the Digital Board.
9.3.4. Simple Power Supply
The main power supply for this set is generated in the PSU
board. Within the Analog board only the 5V, 3V3SW and
8VSTBY lines are generated.
Below are the supply lines from the Simple Power supply on
the
Analog
board:
•
3V3SW
to DAC_ADC and CU
•
3V3STBY to
CU
•
5V
to IOV, CU, PROG, MSP, DIGIO and FV
•
5NSTBY
to IOA, PROG, DAC_ADC and Front board
•
5VSTBY
to IOA, IOV, FV, CU, DAC_ADC and Front
Board
•
8VSTBY to
MSP
•
12VSTBY
to CU, IOV, DAC_ADC and Front Board
•
33VSTBY to
FV
•
VGNSTBY to CU and Front Board
Standby
modes:
In Standby mode the STBY control line is low, switching off
the 3V3D, 5VD, 5ND and 12VE supply and thus reducing the
power
consumption.
9.3.5. Tuner Frontend [1700 : TMQZ2-439A]
It has a RF IN for antenna connection and RF OUT which
provides a RF loop through for connection to the TV.
The Frontend ( Tuner & IF-demodulator ) is controlled by
I
2
C (SCL_5V- and SDA_5V-) lines coming from the
Slave
μ
P [7108].
Complete video processing is done in this unit and the video
output (CVBS) is taken out from the [VIDOUT] pin 17 via
a transistor [7100] as VFV-line to the Video I/O circuitry. The
audio-IF component SIF1 is taken out from the [SIFOUT]
pin 7 for the demodulation by the Multi-sound processor
(MSP).
Audio
demodulator
The sound demodulation is done by the MSP3415 [7600],
which is also fully controlled via I
2
C bus by the Slave
μ
P. The
audio signals are available at pin 26 and pin 27 and fed as
AFER- & AFEL- line to the audio I/O for further processing.
