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參數(shù)資料
| 型號： | ADV7128KR80 |
| 廠商： | ANALOG DEVICES INC |
| 元件分類： | DAC |
| 英文描述： | CMOS 80 MHz, 10-Bit Video DAC |
| 中文描述： | PARALLEL, WORD INPUT LOADING, 10-BIT DAC, PDSO28 |
| 封裝： | SOIC-28 |
| 文件頁數(shù)： | 5/8頁 |
| 文件大?。?/td> | 135K |
| 代理商： | ADV7128KR80 |
ADV7128
REV. 0
–5–
T E RMINOLOGY
Color Video (RGB)
T his 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
T he 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
T he most basic method of sweeping a CRT one line at a time to
generate and display images.
Reference Black Level
T he maximum negative polarity amplitude of the video signal.
Reference White Level
T he maximum positive polarity amplitude of the video signal.
Video Signal
T hat 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 DE SCRIPT ION AND OPE RAT ION
T he 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
T en bits of data (color information) D0–D9 are latched into the
device on the rising edge of each clock cycle. T his data is pre-
sented to the 10-bit DAC and is then converted to an analog
output waveform. See Figure 2.
CLOCK
DATA
ANALOG
OUTPUTS
I
OUT
DIGITAL
INPUTS
D0–D9
Figure 2. Video Data Input/Output
All these digital inputs are specified to accept T T L logic levels.
Clock Input
T he CLOCK input of the ADV7128 is typically the pixel clock
rate of the system. It is also known as the dot rate. T he 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. T his 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 =
T otal Blank T ime Factor. T his 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
T he 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 T T L buffer (e.g.,
74F244).
100
IRE
WHITE
LEVEL
BLACK
LEVEL
17.61 0.66
0 0
mA V
I
OUT
NOTES
1. OUTPUTS CONNECTED TO A DOUBLY TERMINATED 75
LOAD.
2. V
REF
= 1.235V, R
SET
= 560
.
3. RS–343A LEVELS AND TOLERANCES ASSUMED ON ALL LEVELS.
Figure 3. I
OUT
Video Output Waveform
T able I. Video Output T ruth T able for the ADV7128
Description
I
OUT
1
DAC Input Data
WHIT E LEVEL
VIDEO
VIDEO to BLACK
BLACK LEVEL
17.62
video
video
0
3FF
data
data
00H
NOT E
1
T ypical with full scale = 17.62 mA. V
REF
= 1.235 V, R
SET
= 560
.
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相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| ADV7128KR80-REEL | 制造商:Analog Devices 功能描述:DAC 1-CH Segment 10-bit 28-Pin SOIC W T/R 制造商:Rochester Electronics LLC 功能描述:SINGLE,10-BIT VIDEO DAC - Tape and Reel |
| ADV7128KRZ30 | 制造商:Analog Devices 功能描述:DAC 1-CH Segment 10-bit 28-Pin SOIC W |
| ADV7128KRZ50 | 制造商:Analog Devices 功能描述:DAC 1-CH Segment 10-bit 28-Pin SOIC W |
| ADV7128KRZ80 | 制造商:Analog Devices 功能描述:DAC 1-CH Segment 10-bit 28-Pin SOIC W 制造商:Analog Devices 功能描述:SGLE 10B VIDEO DAC |
| ADV7129 | 制造商:AD 制造商全稱:Analog Devices 功能描述:192-Bit, 360 MHz True-Color Video DAC with Onboard PLL |
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