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參數(shù)資料
| 型號(hào)： | ADV7120KN80 |
| 廠商： | ANALOG DEVICES INC |
| 元件分類： | DAC |
| 英文描述： | CAP 0.022UF 50V 5% NP0(C0G) AXIAL RAD.40 BULK R-MIL-PRF-20 |
| 中文描述： | TRIPLE, PARALLEL, 8 BITS INPUT LOADING, 8-BIT DAC, PDIP40 |
| 封裝： | 0.6 INCH, PLASTIC, DIP-40 |
| 文件頁(yè)數(shù)： | 8/12頁(yè) |
| 文件大小： | 188K |
| 代理商： | ADV7120KN80 |
ADV7120
REV. B
–8–
A resistance R
SET
connected between FS ADJUST and GND
determines the amplitude of the output video level according to
the following equations:
IOG (mA) =
12,082
×
V
REF
(V)/R
SET
(
)
IOR, IOB (mA) =
8,628
×
V
REF
(V)/R
SET
(
)
If
SYNC
is not being encoded onto the green channel, then
Equation 1 will be similar to Equation 2.
Using a variable value of R
SET
, as shown in Figure 4, allows for
accurate adjustment of the analog output video levels. Use of a
fixed 560
R
SET
resistor yields the analog output levels as
quoted in the specification page. T hese values also correspond
to the RS-343A video waveform values as shown in Figure 3.
(1)
(2)
TO DACs
ADV7120*
V
AA
V
REF
GND
1k
FS ADJUST
R
SET
560
500
100
*ADDITIONAL CIRCUITRY, INCLUDING
DECOUPLING COMPONENTS,
EXCLUDED FOR CLARITY
ANALOG POWER PLANE
COMP
0.1
μ
F
5V
+
AD589
(1.235V
VOLTAGE
REFERENCE)
I
REF
≈
4mA
Figure 4. Reference Circuit
D/A Converters
T he ADV7120 contains three matched 8-bit D/A converters.
T he DACs are designed using an advanced, high speed, seg-
mented architecture. T he bit currents corresponding to each
digital input are routed to either the analog output (bit = “1”)
or GND (bit = “0”) by a sophisticated decoding scheme. As all
this circuitry is on one monolithic device, matching between the
three DACs is optimized. As well as matching, the use of identi-
cal current sources in a monolithic design guarantees monoto-
nicity and low glitch. T he onboard operational amplifier
stabilizes the full-scale output current against temperature and
power supply variations.
Analog Outputs
T he ADV7120 has three analog outputs, corresponding to the red,
green and blue video signals. A fourth analog output (I
SYNC
) can be
used if it is required to encode video synchronization information
onto the green signal. In this case, I
SYNC
is connected to IOG .
(See “Video Synchronization and Control” section.)
T he red, green and blue analog outputs of the ADV7102 are
high impedance current sources. Each one of these three RGB
current outputs is capable of directly driving a 37.5
load, such
as a doubly terminated 75
coaxial cable. Figure 5a shows the
required configuration for each of the three RGB outputs con-
nected into a doubly terminated 75
load. T his arrangement
will develop RS-343A video output voltage levels across a 75
monitor.
TERMINATION REPEATED THREE TIMES
FOR RED, GREEN AND BLUE DACs
DACs
IOR, IOG, IOB
(CABLE)
Z
O
= 75
Z
= 75
(SOURCE
TERMINATION)
Z
= 75
(MONITOR)
Figure 5a. Analog Output Termination for RS-343A
One suggested method of driving RS-170 video levels into a 75
monitor is shown in Figure 5b. T he output current levels of the
DACs remain unchanged but the source termination resistance,
Z
S
, on each of the three DACs is increased from 75
to 150
.
TERMINATION REPEATED THREE TIMES
FOR RED, GREEN AND BLUE DACs
DACs
IOR, IOG, IOB
(CABLE)
Z
O
= 75
Z
= 150
(SOURCE
TERMINATION)
Z
= 75
(MONITOR)
Figure 5b. Analog Output Termination for RS-170
More detailed information regarding load terminations for vari-
ous output configurations, including RS-343A and RS-170, is
available in an application note entitled “Video Formats & Re-
quired Load T erminations” available from Analog Devices,
publication number E1228-15-1/89.
Figure 3 shows the video waveforms associated with the three
RGB outputs driving the doubly terminated 75
load of Figure
5a. As well as the gray scale levels, black level to white level, the
diagram also shows the contributions of
SYNC
and
BLANK
.
T hese control inputs add appropriately weighted currents to the
analog outputs, producing the specific output level requirements
for video applications. T able I details how the
SYNC
and
BLANK
inputs modify the output levels.
Gray Scale Operation
T he ADV7120 can be used for stand-alone, gray scale (mono-
chrome) or composite video applications (i.e., only one channel
used for video information). Any one of the three channels, red,
green or blue, can be used to input the digital video data. T he
two unused video data channels should be tied to logical zero.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| ADV7120KP30 | 制造商:Analog Devices 功能描述:DAC 3-CH Segment 8-bit 44-Pin PLCC 制造商:Rochester Electronics LLC 功能描述:TRIPLE 8 BIT VIDEO DAC IC - Bulk 制造商:Analog Devices 功能描述:IC 8-BIT VIDEO DAC |
| ADV7120KP30-REEL | 制造商:Analog Devices 功能描述:DAC 3-CH Segment 8-bit 44-Pin PLCC T/R 制造商:Rochester Electronics LLC 功能描述:TRIPLE 8-BIT VIDEO DAC IC - Tape and Reel |
| ADV7120KP50 | 制造商:Analog Devices 功能描述:DAC 3-CH Segment 8-bit 44-Pin PLCC 制造商:Rochester Electronics LLC 功能描述:TRIPLE 8 BIT VIDEO DAC IC - Bulk |
| ADV7120KP50-REEL | 制造商:Analog Devices 功能描述:DAC 3-CH Segment 8-bit 44-Pin PLCC T/R 制造商:Rochester Electronics LLC 功能描述:TRIPLE 8 BIT VIDEO DAC IC - Tape and Reel |
| ADV7120KP80 | 制造商:Analog Devices 功能描述:DAC 3-CH Segment 8-bit 44-Pin PLCC 制造商:Rochester Electronics LLC 功能描述:TRIPLE 8 BIT VIDEO DAC IC - Bulk |
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