ADV7170SU AD [Analog Devices], ADV7170SU Datasheet - Page 41

• Manufacturer Part Number: ADV7170SU
• Manufacturer: AD [Analog Devices]

When external buffering is needed of the ADV7170/ADV7171
DAC outputs, the configuration in Figure 83 is recommended.
This configuration shows the DAC outputs running at half
(18 mA) their full current (36 mA) capability. This will allow
the ADV7170/ADV7171 to dissipate less power; the analog cur-
rent is reduced by 50% with a R
This mode is recommended for 3.3 V operation as optimum
performance is obtained from the DAC outputs at 18 mA with a
V
outputs (see buffer circuit in Figure 84).
REV. 0
AA
of 3.3 V. This buffer also adds extra isolation on the video
SET
300
PIXEL
PORT
of 300
R
Figure 83. Output DAC Buffering Configuration
SET
Figure 84. Recommended Output DAC Buffer
V
and a R
DIGITAL
REF
CORE
ADV7170/ADV7171
INPUT
V
AA
OPTIONAL DAC BUFFERING
LOAD
of 75 .
75
APPENDIX 8
DAC A
DAC B
DAC C
V
DAC D
AA
2N2907
36
–41–
When calculating absolute output full-scale current and voltage,
use the following equations:
75
OUTPUT TO
TV/MONITOR
OUTPUT
BUFFER
OUTPUT
BUFFER
OUTPUT
BUFFER
OUTPUT
BUFFER
V
I
K
OUT
OUT
4.2146 constant , V
I
V
OUT
REF
R
CVBS
CVBS
LUMA
CHROMA
SET
R
K
LOAD
ADV7170/ADV7171
REF
1.235 V