ADV7195 Datasheet, PDF (10/36 Pages) Analog Devices – Multiformat Progressive Scan/HDTV Encoder with Three 11-Bit DACs and 10-Bit Data Input

ADV7195
FUNCTIONAL DESCRIPTION
Digital Inputs
The digital inputs of the ADV7195 are TTL-compatible. 30-bit
YCrCb or RGB pixel data in 4:4:4 format or 20-bit YCrCb
pixel data in 4:2:2 format is latched into the device on the rising
edge of each clock cycle at 27 MHz in Progressive Scan Mode or
74.25 MHz or 74.1785 MHz in HDTV mode. It is also possible
to input 3 × bit RGB data in 4:4:4 format to the ADV7195. It
is recommended to input data in 4:2:2 mode to make use of the
chroma SSAFs on the ADV7195. As can be seen in Figures 6 and
7, this filter has 0 dB passband response and prevents signal com-
ponents being loaded back into the frequency band. In 4:4:4 input
mode, the video data is already interpolated by the external
input device and the chroma SSAFs of the ADV7195 are bypassed.
ATTEN 10dB
RL –10.0dBm
VAVG 1
10dB/
MKR 0dB
3.18MHz
START 100kHz
RBW 10kHz
VBW 300Hz
STOP 20.00MHz
SWP 17.0SEC
Figure 6. ADV7195 SSAF Response to a 2.5 MHz Chroma
Sweep Using 4:2:2 Input Mode
ATTEN 10dB
RL –10.0dBm
VAVG 4
10dB/
MKR –3.00dB
3.12MHz
START 100kHz
RBW 10kHz
VBW
STOP 20.00MHz
300Hz
SWP 17.0SEC
Figure 7. Conventional Filter Response to a 2.5 MHz
Chroma Sweep Using 4:4:4 Input Mode
Control Signals
The ADV7195 accepts sync control signals accompanied by
valid 4:2:2 or 4:4:4 data. These external horizontal, vertical, and
blanking pulses (or EAV/SAV codes) control the insertion of
appropriate sync information into the output signals.
Analog Outputs
The analog Y signal is output on the 11-bit + Sync DAC A,
the color component analog signals on the 11-bit DAC B and
DAC C conforming to EIA-770.1 or EIA-770.2 standards in PS
mode or EIA-770.3 in HDTV mode. R_SET has a value of 2470 Ω
(EIA-770.1, EIA-770.2, EIA-770.3), R_LOAD has a value of 300 Ω.
For RGB outputs conforming to RS-170/RS-343A output stan-
dards R_SET must have a value of 2820 Ω.
Undershoot Limiter
A limiter can be applied to the Y data before it is applied to the
DACs. Available limit values are –1.5 IRE, –6 IRE, –11 IRE below
blanking. This functionality is available in Progressive Scan
Mode only.
I²C Filter
A selectable internal I²C filter allows significant noise reductions
on the I²C interface. In setting ALSB high, the input bandwidth
on the I²C lines is reduced and pulses of less than 50 ns are not
passed to the I²C controller. Setting ALSB low allows greater
input bandwidth on the I²C lines.
Internal Test Pattern Generator
The ADV7195 can generate a crosshatch pattern (white lines
against a black background). Additionally, the ADV7195 can
output a uniform color pattern. The color of the lines or uni-
form field/frame can be programmed by the user.
Y/CrCb Delay
The Y output and the color component outputs can be delayed
wrt the falling edge of the horizontal sync signal by up to four
clock cycles.
Gamma Correction
Gamma correction may be performed on the luma data. The
user has the choice to use either of two different gamma curves,
A or B. At any one time one of these curves is operational if
gamma correction is enabled. Gamma correction allows the
mapping of the luma data to a user-defined function.
54 MHz Operation
In Progressive Scan mode, it is possible to operate the three
output DACs at 54 MHz or 27 MHz. The ADV7195 is sup-
plied with a 27 MHz clock synced with the incoming data. If
required, a second stage interpolation filter interpolates the data
to 54 MHz before it is applied to the three output DACs.
The second stage interpolation filter is controlled by MR36. After
applying a Reset, it is recommended to toggle this bit. Before
toggling this bit, 3Ehex must be written to Address 09hex.
PROGRAMMABLE SHARPNESS FILTER
Sharpness Filter Mode is applicable to the Y data only in
Progressive Scan Mode.
The desired frequency response can be chosen by the user in
programming the correct value via the I²C. The variation of
frequency responses can be seen in the figures on the follow-
ing pages.
–10–
REV. A