Circuit Descriptions, Abbreviation List, and IC Data Sheets
EN 88
LC7.2E LA
9.
9.3
DC/DC converters
A switch generates the +5.2 V (+5V_SW) from the +5.2 V
(+5V_STANDBY) supply voltage. For LCD sets, this switch is
mounted on-board the SSB. For PDP sets, this switch is
mounted on the Power Supply Panel. This results in the
+5V_STANDBY (and +5V_SW for PDP sets) voltage(s),
coming from the Power Supply Unit, is (are) used as input for
the on-board DC/DC converters.
They deliver the following voltages to the board:
•
+3.3 V (+3V3_STBY)
•
+5.2 V (+5V_SW) (only for LCD sets)
•
+1.8 V (+1V8S_SW)
•
+34 V (+VTUN)
•
+3.3 V (+3V3_SW)
•
+3.3 V (+3V3_MOJO)
•
+1.2 V (+1V2_MOJO)
An overview can be found in figure “DC-DC converter block
diagram”.
Figure 9-4 DC-DC converter block diagram
The +5 V switch, needed for the switch voltages, is for LCD
sets physically mounted on the SSB, whereas for the PDP sets
it is physically mounted on the PSU board.
9.4
Front-End
This chassis uses different tuners depending on the region. An
overview of region-dependency can be found in table “Tuner
diversity”.
Table 9-1 Tuner diversity
The TD1316AF hybrid tuner used, is capable of receiving both
analogue and digital (DVB-T) signals. For the application in this
chassis see figure “Tuner IF diagram”.
Figure 9-5 Tuner IF diagram
While receiving analogue signals, the signal coming from the
tuner is fed to the IF demodulator (through the SAW filters) and
then passed to the Trident Video Processor.
While receiving digital signals, the signal coming from the tuner
is fed to the channel decoder, to the MPEG decoder and then
to the Trident Video Processor.
9.4.1
Video IF Amplifier
The IF-filter is integrated in a SAW (Surface Acoustic Wave)
filter. One for filtering IF-video (item 1102) and one for IF-audio
(item 1103). The type of these filters depends on the standard
to be received (region-dependency). Some filters can be
switched to another standard, what makes them suitable for
applications in multi-standard platforms. An overview of the
SAW filter diversity can be found in table “SAW filter diversity”.
Table 9-2 SAW filter diversity
Switching is done by the microcontroller via SAW_SW. In table
“SAW filter switching” is explained how to address the different
system standards.
Table 9-3 SAW filter switching
The hybrid tuner TDA1316AF, used in Europe sets, needs to
be switched between digital and analogue mode. This is done
by the microcontroller via DVB_SW. Refer to table “Hybrid
tuner digital/analogue switching” for details.
Table 9-4 Hybrid tuner digital/analogue switching
Region
Tuner
Type
Europe
TD1316AF
Hybrid
UV1318S
analogue
AP
UV1316E
analogue
China
TEDE9
analogue
Latam
UV1338
analogue
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270707
(n.a. for LC7.xH)
(n.a. for LC7.xH)
(n.a. for LC7.xH)
SAW filter
Switching Y/N
Region
Video/Audio
OFWK3953M
No
Europe
Video
OFWK9656M
Yes
Europe
Audio
OFWK7265L
Yes
AP
Video
OFWK9361L
No
AP
Sound
OFWK3956L
No
China
Video
OFWK3955L
No
China
Video
OFWK9352L
No
China
Audio
OFWM1967L
No
LATAM
Video/Audio
Region
SAW_SW
System
Europe
1
L’
0
other systems
AP
1
B/G, D/K, I
0
M/N
China
1
B/G, D/K, I
0
M/N
LATAM
n.a.
M/N
Region
DVB_SW
Mode
Europe
1
analogue reception
0
Digital reception
Tuner
Video
SAW filter
Audio
SAW filter
Switch IC
IF Demodulator
CVBS
2
nd
SIF
Digital IF
36.16MHz
4MHz
RFAGC
RF AGC_analogue
I2C
IF AGC
Supply
+5V/+33V
RF AGC_digital
I2C_analogue
I2C_digital
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