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PDF ADV7128 Data sheet ( Hoja de datos )
| Número de pieza | ADV7128 | |
| Descripción | CMOS 80 MHz/ 10-Bit Video DAC | |
| Fabricantes | Analog Devices | |
| Logotipo |  |
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a
CMOS
80 MHz, 10-Bit Video DAC
FEATURES
80 MHz Pipelined Operation
10-Bit D/A Converters
RS-343A/RS-170 Compatible Outputs
TTL Compatible Inputs
+5 V CMOS Monolithic Construction
28-Pin SOIC Package
APPLICATIONS
High Definition Television (HDTV)
High Resolution Color Graphics
Digital Radio Modulation
CAE/CAD/CAM Applications
Image Processing
Instrumentation
Video Signal Reconstruction
Direct Digital Synthesis (DDS) & I/O Modulation
Wireless LAN
Wireless Local Loop
SPEED GRADES
80 MHz
50 MHz
30 MHz
CLOCK
ADV7128
FUNCTIONAL BLOCK DIAGRAM
FS
VAA ADJUST VREF
ADV7128
REFERENCE
AMPLIFIER
COMP
D0
10
DATA
10
REGISTER
DAC
IOUT
D9
GND
GENERAL DESCRIPTION
The ADV7128 (ADV®) is a video speed, digital-to-analog con-
verter on a single monolithic chip. It consists of a high speed,
10-bit, video D/A converters; a standard TTL input interface;
and a high impedance, analog output, current source.
The ADV7128 has a 10-bit pixel input port. A single +5 V
power supply, an external 1.23 V reference and pixel clock input
are and all that are required to make the part operational.
The ADV7128 is capable of generating video output signals
which are compatible with RS-343A, RS-170 and most pro-
posed production system HDTV video standards, including
SMPTE 240M.
The ADV7128 is fabricated in a +5 V CMOS process. Its
monolithic CMOS construction ensures greater functionality
with low power dissipation. The ADV7128 is available in a 28-
lead small outline IC (SOIC).
PRODUCT HIGHLIGHTS
1. Fast video refresh rate, 80 MHz.
2. Guaranteed monotonic to 10 bits. Ten bits of resolution al-
lows for implementation of linearization functions such as
gamma correction and contrast enhancement.
3. Compatible with a wide variety of high resolution color
graphics systems including RS-343A/RS-170 and the pro-
posed SMPTE 240M standard for HDTV.
4. Combined with a numerically controlled oscillator (AD9955),
it forms a complete frequency synthesizer (DDS).
5. Using the parts reduced power output DAC modes, it is
ideal for power and cost sensitive communications type
applications.
ADV is a registered trademark of Analog Devices, Inc.
REV. 0
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties
which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Analog Devices.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 617/329-4700
Fax: 617/326-8703
1 page  
ADV7128
TERMINOLOGY
Color Video (RGB)
This usually refers to the technique of combining the three pri-
mary colors of red, green and blue to produce color pictures
within the usual spectrum. In RGB monitors, three DACs are
required, one for each color.
Gray Scale
The discrete levels of video signal between reference black and
reference white levels. A 10-bit DAC contains 1024 different
levels, while an 8-bit DAC contains 256.
Raster Scan
The most basic method of sweeping a CRT one line at a time to
generate and display images.
Reference Black Level
The maximum negative polarity amplitude of the video signal.
Reference White Level
The maximum positive polarity amplitude of the video signal.
Video Signal
That portion of the composite video signal which varies in gray
scale levels between reference white and reference black. Also
referred to as the picture signal, this is the portion which may be
visually observed.
CIRCUIT DESCRIPTION AND OPERATION
The ADV7128 contains one 10-bit D/A converter, with one in-
put channel containing a 10-bit register. Also integrated on
board the part is a reference amplifier.
Digital Inputs
Ten bits of data (color information) D0–D9 are latched into the
device on the rising edge of each clock cycle. This data is pre-
sented to the 10-bit DAC and is then converted to an analog
output waveform. See Figure 2.
CLOCK
DIGITAL
INPUTS
D0–D9
DATA
ANALOG
OUTPUTS
IOUT
Figure 2. Video Data Input/Output
All these digital inputs are specified to accept TTL logic levels.
Clock Input
The CLOCK input of the ADV7128 is typically the pixel clock
rate of the system. It is also known as the dot rate. The dot rate,
and hence the required CLOCK frequency, will be determined
by the on-screen resolution, according to the following
equation:
Dot Rate = (Horiz Res) × (Vert Res) × (Refresh Rate)/
(Retrace Factor)
Horiz Res
= Number of Pixels/Line.
Vert Res
= Number of Lines/Frame.
Refresh Rate
= Horizontal Scan Rate. This is the rate at
which the screen must be refreshed, typi-
cally 60 Hz for a noninterlaced system or
30 Hz for an interlaced system.
Retrace Factor =
Total Blank Time Factor. This takes into
account that the display is blanked for a
certain fraction of the total duration of
each frame (e.g., 0.8).
If we, therefore, have a graphics system with a 1024 × 1024
resolution, a noninterlaced 60 Hz refresh rate and a retrace fac-
tor of 0.8, then:
Dot Rate = 1024 × 1024 × 60/0.8
= 78.6 MHz
The required CLOCK frequency is thus 78.6 MHz.
All video data and control inputs are latched into the ADV7128
on the rising edge of CLOCK, as previously described in the
“Digital Inputs” section. It is recommended that the CLOCK
input to the ADV7128 be driven by a TTL buffer (e.g.,
74F244).
IOUT
mA V
17.61 0.66
WHITE
LEVEL
100
IRE
00
NOTES
1. OUTPUTS CONNECTED TO A DOUBLY TERMINATED 75Ω LOAD.
2. VREF = 1.235V, RSET = 560Ω.
3. RS–343A LEVELS AND TOLERANCES ASSUMED ON ALL LEVELS.
BLACK
LEVEL
Figure 3. IOUT Video Output Waveform
Table I. Video Output Truth Table for the ADV7128
Description
WHITE LEVEL
VIDEO
VIDEO to BLACK
BLACK LEVEL
IOUT1
17.62
video
video
0
DAC Input Data
3FF
data
data
00H
NOTE
1Typical with full scale = 17.62 mA. VREF = 1.235 V, RSET = 560 Ω.
REV. 0
–5–
5 Page | ||
| Páginas | Total 8 Páginas | |
| PDF Descargar | [ Datasheet ADV7128.PDF ] | |
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