adv7173 Analog Devices, Inc., adv7173 Datasheet - Page 51

• Manufacturer Part Number: adv7173
• Description: With Six Dacs 10 Bits , Color Control And Enhanced Power Management
• Manufacturer: Analog Devices, Inc.

When external buffering is needed of the ADV7172/ADV7173
DAC outputs, the configuration in Figure 94 is recommended.
This configuration shows the DAC outputs, A, B, C, running at
half (18 mA) their full current (36 mA) capability. This will
allow the ADV7172/ADV7173 to dissipate less power; the analog
current is reduced by 50% with a R
600 Ω and an R
3.3 V operation as optimum performance is obtained from the
If an output filter is required for the CVBS, Y, UV, Chroma
and RGB outputs of the ADV7172/ADV7173, the filter shown
below can be used. The plot of the filter characteristics is
shown in Figure 93. An Output Filter is not required if the
outputs of the ADV7172/ADV7173 are connected to most
analog monitors or analog TVs; however, if the output signals
are applied to a system where sampling is used (e.g., Digital
TVs), then a filter is required to prevent aliasing.
600
300
PIXEL
PORT
FILTER I/P
R
R
SET2
SET1
75
V
DIGITAL
REF
CORE
ADV7172/ADV7173
LOAD
of 75 Ω. This mode is recommended for
270pF
V
AA
1.8 H
DAC A
DAC B
DAC C
DAC D
DAC E
DAC F
22pF
SET1
330pF
= 300 Ω and R
OUTPUT
BUFFER
OUTPUT
BUFFER
OUTPUT
BUFFER
OUTPUT
BUFFER
OUTPUT
BUFFER
OUTPUT
BUFFER
OPTIONAL OUTPUT FILTER
OPTIONAL DAC BUFFERING
FILTER O/P
CVBS
LUMA
CHROMA
G
B
R
SET2
APPENDIX 7
APPENDIX 8
=
DAC outputs at 18 mA with a V
extra isolation on the video outputs (see buffer circuit in Figure
95). Note that DACs D, E, and F will always require buffering
as the full-scale output current from these DACs is limited to
8.66 mA. With DACs A, B, and C, buffering is optional, based
on the user requirements for performance and power consumption.
When calculating absolute output full-scale current and voltage,
use the following equations:
FILTER O/P
OPTIONAL
–10
–20
–30
–40
–50
–60
–70
–80
100k
0
INPUT/
V
I
K = 4.2146 constant , V
OUT
OUT
=
= I
(
V
OUT
REF
R
SET
4
3
1M
× R
× K
AD8051
FREQUENCY – Hz
V
V
CC
CC
LOAD
ADV7172/ADV7173
5
2
)
+
–
AA
of 3.3 V. This buffer also adds
1
REF
10M
= 1.235 V
OUTPUT TO
TV MONITOR
100M