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ADV7175 View Datasheet(PDF) - Analog Devices

Part Name
Description
Manufacturer
ADV7175 Datasheet PDF : 36 Pages
1 2 3 4 5 6 7 8 9 10 Next Last
ADV7175/ADV7176
0
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0
2
4
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10
12
FREQUENCY – MHz
Figure 10. NTSC UV Filter
0
–10
–20
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0
2
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FREQUENCY – MHz
Figure 11. PAL UV Filter
COLOR BAR GENERATION
The ADV7175/ADV7176 can be configured to generate 75%
amplitude, 75% saturation (75/7.5/75/7.5) for NTSC or 75%
amplitude, 100% saturation (100/0/75/0) for PAL color bars.
These are enabled by setting MR17 of Mode Register 1 to
Logic “1.”
SQUARE PIXEL MODE
The ADV7175/ADV7176 can be used to operate in square
pixel mode. For NTSC operation an input clock of 24.54 MHz
is required. Alternatively, for PAL operation, an input clock of
29.5 MHz is required. The internal filters scale accordingly for
square pixel mode operation.
COLOR SIGNAL CONTROL
The color information can be switched on and off the video
output using Bit MR24 of Mode Register 2.
BURST SIGNAL CONTROL
The burst information can be switched on and off the video
output using Bit MR25 of Mode Register 2.
NTSC PEDESTAL CONTROL
The pedestal information on both odd and even fields can be
controlled on a line by line basis using the NTSC Pedestal
Control Registers. This allows the pedestals to be controlled
during the vertical blanking interval (Lines 10 to 25).
SUBCARRIER RESET
Together with the SCRESET/RTC PIN and Bits MR22 and
MR21 of Mode Register 2, the ADV7175/ADV7176 can be
used in subcarrier reset mode. The subcarrier will reset to field
0 at the start of the following field when a high to low transition
occurs on this input pin.
REAL TIME CONTROL
Together with the SCRESET/RTC PIN and Bits MR22 and
MR21 of Mode Register 2, the ADV7175/ADV7176 can be
used to lock an external video source. The real time control
mode allows the ADV7175/ADV7176 to automatically alter the
subcarrier frequency to compensate for line length variation.
When the part is connected to a device that outputs out a digi-
tal datastream in the RTC format (such as a Phillips SAA7110
video decoder), the part will automatically change to the com-
pensated subcarrier frequency on a line by line basis. This
digital datastream is 67 bits wide and the subcarrier is con-
tained in bits 0 to 21. Each bit is 2 clock cycles long.
COMPOSITE
VIDEO
e.g. VCR
VIDEO
DECODER
(e.g.SAA7110)
OR CABLE
M
U
X
MPEG
DECODER
CLOCK
SCRESET/RTC
GREEN/LUMA/Y
P7–P0
RED/CHROMA/V
BLUE/COMPOSITE/U
HSYNC
COMPOSITE
FIELD/VSYNC
ADV7175/ADV7176
Figure 12. RTC Connections
PIXEL TIMING DESCRIPTION
The ADV7175/ADV7176 can operate in either 8-bit or 16-bit
YCrCb Mode.
8-Bit YCrCb Mode
This default mode accepts multiplexed YCrCb inputs through
the P7–P0 pixel inputs. The inputs follow the sequence Cb0,
Y0 Cr0, Y1 Cb1, Y2, etc. The Y, Cb and Cr data are input on
a rising clock edge.
16-Bit YCrCb Mode
This mode accepts Y inputs through the P7-P0 pixel inputs and
multiplexed CrCb inputs through the P15-P8 pixel inputs. The
data is loaded on every second rising clock edge of CLOCK.
The inputs follow the sequence Cb0, Y0 Cr0, Y1 Cb1, Y2, etc.
VIDEO TIMING DESCRIPTION
The ADV7175/ADV7176 is intended to interface to off the shelf
MPEG1 and MPEG2 Decoders. As a consequence the
ADV7175/ADV7176 accepts 4:2:2 YCrCb pixel data via a
CCIR-656 pixel port and has several video timing modes of
operation that allow it to be configured as either system master
video timing generator or a slave to the system video timing gen-
erator. The ADV7175/ADV7176 generates all of the required
horizontal and vertical timing periods and levels for the analog
video outputs.
The ADV7175/ADV7176 calculates the width and placement
of analog sync pulses, blanking levels and color burst envelopes.
Color bursts are disabled on appropriate lines and serration and
equalization pulses are inserted where required.
(Continued on page 15)
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REV. A

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