AN2471 Datasheet, PDF (4/12 Pages) STMicroelectronics – STMAV335 has three sets

Video input & output ports
2
Video input & output ports
AN2471
Note:
STMAV335 can switch three sets of video input to a single set of video output. On the
evaluation board, the three sets of video input are:
1. RGB (VGA port)
2. YPbPr (3 RCA connector)
3. CVBS (RCA connector) & S-VIDEO ( S-connector)
In the real system, the outputs of STMAV335 are directly connected to the video receiver.
However for the STMAV335 evaluation board, each output line branches to three signal
lines. The reason for this is because each set of different video signal has a different type of
connector. During evaluation, each output line should be branched and be connected to a
different video connector on the display unit back panel by a cable.
To avoid any PCB trace stub, the 1 to 3 branching of each output line cannot be shorted on
the board. The branching of the output line is done by a zero ohm resistor. Depending on
which particular set of video signal is active, the zero ohm resistors should be soldered such
that the output of STMAV335 is connected to the right video output connector.
Table 2. Evaluation board video input & output
Input
Output
SEL
RGB (VGA_IN)
RGB (VGA_OUT)
SEL1 = ‘1’
SEL2 = ‘0’
Y (Y_IN)
Pb (Pb_IN)
Pr (Pr_IN)
CVBS (CVBS_IN)
S-VIDEO
(S VIDEO_IN)
Y (Y_OUT)
Pb (Pb_OUT)
Pr (Pr_OUT)
CVBS (CVBS_OUT)
S-VIDEO
(S VIDEO_OUT)
SEL1 = ‘0’
SEL2 = ‘1’
SEL1 = ‘0’
SEL2 = ‘0’
SEL1→ JP9, SEL2 → JP10, OPEN = '1' & CLOSE = '0'
0Ω Jumper output
J11 = ‘R’
J12 = ‘G’
J13 = ‘B’
J11 = ‘Y’
J12 = ‘Pb’
J13 = ‘Pr’
J11 = ‘CVBS’
J12 = ‘Y(S)’
J13 = ‘C’
2.1
Video input conditioning
The blanking level might vary between different video transmitters. This STMAV335
evaluation board can handle video signals with blanking level of 0V to 2.5 V.
If video signal blanking levels are outside the above range, some input conditioning should
be done to modify the blanking level to the range specified.
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