ADV7172/ADV7173
4
2
4
3
0
2
–2
–4
–6
–8
–10
–12
1
0
–1
–2
–3
1
2
3
4
5
6
0
1
2
3
4
5
6
7
FREQUENCY – MHz
FREQUENCY – MHz
Figure20. ExtendedModeLumaFilterwithProgrammable
Gain, Positive Response
Figure 21. Extended Mode Luma Filter with Programmable
Gain, Combined Response
COLOR BAR GENERATION
onto the Y data in PAL mode, NTSC mode without pedestal or
NTSC mode with pedestal, in which case it is added directly
onto the 7.5 IRE pedestal already present.
The ADV7172/ADV7173 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 MR46 of Mode Register 4 to
Logic “1.”
The level added is programmed by the user into the Brightness
Control Register (Bits 4–0) and the user is capable of adding
from 0 IRE to a maximum of 14 IRE in 32 (25) steps. Because
of different gains in the datapath for each mode, different values
may need to be programmed to obtain the same IRE setup level
in each mode. Maximum brightness is achieved when 31 is
programmed into the Brightness Control Register. Table II
illustrates the maximum setup/brightness amplitudes available in
the various modes. Note that if a level of less than 7.5 IRE is
required on the Y data in NTSC mode, then NTSC without
pedestal must be the mode selected.
SQUARE PIXEL MODE
The ADV7172/ADV7173 can be used to operate in square pixel
mode. For NTSC operation, an input clock of 24.5454 MHz
is required. Alternatively, for PAL operation, an input clock of
29.5 MHz is required. The internal timing logic adjusts ac-
cordingly for square pixel mode operation.
COLOR SIGNAL CONTROL
The color information can be switched on and off the video
output using Bit MR44 of Mode Register 4.
Table II. Maximum Brightness Levels Available
Brightness Control
BURST SIGNAL CONTROL
The burst information can be switched on and off the video
output using Bit MR45 of Mode Register 4.
Mode
Register
Setup
NTSC No Pedestal
NTSC Pedestal
PAL
00011111
00011111
00011111
14 IRE
13 IRE
99 mV
NTSC PEDESTAL CONTROL
The pedestal on both odd and even fields can be controlled on
a line-by-line basis using the NTSC Pedestal Control Regis-
ters. This allows the pedestals to be controlled during the
Vertical Blanking Interval (lines 10 to 25 and lines 273 to 288).
Color Saturation Control
Color adjustment is achieved by scaling the Cr and Cb input
data by a factor programmed by the user into the Color Control
Registers 1 and 2, Bits 5–0. This factor allows the data to be
scaled between 75% and 125%.
COLOR CONTROLS
The ADV7172/ADV7173 allows the user the advantage of con-
trolling the brightness, contrast, hue and saturation of the color.
Contrast Control
Hue Control
Contrast adjustment is achieved by scaling the Y input data
by a factor programmed by the user into the Contrast Control
Register Bits 5–0. This factor allows the data to be scaled
between 75% and 125%.
The hue adjustment is achieved on the composite and chroma
outputs by adding a phase offset onto the color subcarrier in the
active video but leaving the color burst unmodified, i.e., only
the phase between the video and the color burst is modified
and hence the hue is shifted. Hue adjustment is under the con-
trol of the Hue Control Register. The ADV7172/ADV7173
provides a range of ±22° change in increments of 0.17578125°.
Brightness Control
The brightness is controlled by adding a programmable setup
level onto the scaled Y data. This brightness level may be added
–14–
REV. A
ADI [ ADI ]
