adv7197 Analog Devices, Inc., adv7197 Datasheet - Page 18

• Manufacturer Part Number: adv7197
• Description: Multiformat Hdtv Encoder With Three 11-bit Dacs
• Manufacturer: Analog Devices, Inc.

ADV7197
Video Output Buffer and Optional Output Filter
Output buffering is necessary in order to drive output devices,
such as HDTV monitors.
Analog Devices produces a range of suitable op amps for this
application. A suitable op amp would be the AD8057. More
information on line driver buffering circuits is given in the rel-
evant op amp data sheets.
An optional analog reconstruction LPF might be required as an
antialias filter if the ADV7197 is connected to a device that
requires this filtering.
The Eval ADV7196/ADV7197EB evaluation board uses the
ML6426 Microlinear IC, which provides buffering and low-pass
filtering for HDTV applications.
The Eval ADV7196/ADV7197EB Rev. B and Rev. C evaluation
boards use the AD8057 as a buffer and a 6th order LPF.
The Application Note, AN-TBD, describes in detail these two
designs and should be consulted when designing external filter
and buffers for Analog Devices Video Encoders.
ADV7197
DAC A
DAC B
DAC C
LPF
LPF
LPF
AD8057
AD8057
AD8057
+5V
–5V
+5V
–5V
5V
5V
To calculate the output full-scale current and voltage, the fol-
lowing equations should be used:
where:
K = 5.66 (for input ranges 64–940, 64–960, output standards
EIA770.3)
K = 6.46 (for input ranges 0–1023, output standards
RS170/343A
V
REF
= 1.235 V.
75
75
75
0.1 F
0.1 F
0.1 F
0.1 F
0.1 F
0.1 F
75
75
75
COAX
COAX
COAX
10 F
10 F
10 F
10 F
10 F
10 F
I
OUT
V
OUT
75
75
= (V
75
HDTV MONITOR
= I
REF
OUT
× K)/R
× R
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SET