ADV7190/ADV7191
COLOR BAR GENERATION
FEATURES: FUNCTIONAL DESCRIPTION
BRIGHTNESS DETECT
The ADV7190/ADV7191 can be configured to generate 100/
7.5/75/7.5 color bars for NTSC or 100/0/75/0 color bars for
PAL. (Mode Register 4.)
This feature is used to monitor the average brightness of the
incoming Y signal on a field-by-field basis. The information is
read from the I2C and based, on this information, the color
saturation, contrast and brightness controls can be adjusted (for
example to compensate for very dark pictures). (Brightness Detect
Register.)
COLOR BURST SIGNAL CONTROL
The burst information can be switched on and off the composite
and chroma video output. (Mode Register 4.)
COLOR CONTROLS
CHROMA/LUMA DELAY
The ADV7190/ADV7191 allows the user to control the brightness,
contrast, hue, and saturation of the color. The control regis-
ters may be double-buffered, meaning that any modification to
the registers will be done outside the active video region and,
therefore, changes made will not be visible during active video.
The luminance data can be delayed by maximum of six clock
cycles. Additionally the Chroma can be delayed by a maximum
of eight clock cycles (one clock cycle at 27 MHz). (Timing
Register 0 and Mode Register 9.)
Contrast Control
Contrast adjustment is achieved by scaling the Y input data by a
factor programmed by the user. This factor allows the data to be
scaled between 0% and 150%. (Contrast Control Register.)
LUMA DELAY
CHROMA DELAY
Brightness Control
The brightness is controlled by adding a programmable setup level
onto the scaled Y data.
For NTSC with pedestal, the setup can vary from 0 IRE to
22.5 IRE. For NTSC without pedestal and PAL, the setup can
vary from –7.5 IRE to +15 IRE. (Brightness Control Register.)
Figure 26. Chroma Delay
Figure 27. Luma Delay
Color Saturation
CLAMP OUTPUT
Color adjustment is achieved by scaling the Cr and Cb input
data by a factor programmed by the user. This factor allows the
data to be scaled between 0% and 200%. (U Scale Register and
V Scale Register.)
The ADV7190/ADV7191 has a programmable clamp TTL
output signal. This clamp signal is programmable to the front
and back porch. The clamp signal can be varied by one to
three clock cycles in a positive and negative direction from the
default position. (Mode Register 5, Mode Register 7.)
Hue Adjust Control
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 colorburst is modified and
hence the hue is shifted. The ADV7190/ADV7191 provides a
range of 22° in increments of 0.17578125°. (Hue Adjust
Register.)
CLAMP O/P SIGNALS
CVBS
OUTPUT PIN
MR57 = 1
MR57 = 0
CLAMP
OUTPUT PIN
CHROMINANCE CONTROL
The color information can be switched on and off the com-
posite, chroma and color component video outputs. (Mode
Register 4.)
Figure 28. Clamp Output Timing
CSO, HSO AND VSO OUTPUTS
The ADV7190/ADV7191 supports three output timing sig-
nals, CSO (Composite Sync Signal), HSO (Horizontal Sync
Signal) and VSO (Vertical Sync Signal). These output TTL sig-
nals are aligned with the analog video outputs. See Figure 29 for
an example of these waveforms. (Mode Register 7.)
UNDERSHOOT LIMITER
A limiter is placed after the digital filters. This prevents any
synchronization problems for TVs. The level of undershoot is
programmable between –1.5 IRE, –6 IRE, –11 IRE when operat-
ing in 4× Oversampling. In 2× Oversampling mode the limits are
–7.5 IRE and 0 IRE. (Mode Register 9 and Timing Register 0.)
EXAMPLE:- NTSC
525
1
2
3
4
5
6
7
8
9
10
11–19
OUTPUT
VIDEO
DIGITAL NOISE REDUCTION
DNR is applied to the Y data only. A filter block selects the
high frequency, low amplitude components of the incoming
signal (DNR Input Select). The absolute value of the filter output
is compared to a programmable threshold value (DNR Thresh-
old Control).
CSO
HSO
VSO
Figure 29. CSO, HSO, VSO Timing Diagram
Two DNR modes are available: DNR Mode and DNR Sharp-
ness Mode.
REV. 0
–17–
ADI [ ADI ]
