ADA4430-1
Rev. C | Page 15 of 20
RECONSTRUCTION FILTER APPLICATIONS
Figure 33 illustrates how to use the ADA4430-1 as a dc-coupled
reconstruction filter with a pass-band gain of 2 following the
low power ADV7190/ADV7191 video encoder. One ADV7190/
ADV7191 output DAC is shown for illustrative purposes, and
the remaining portions of the ADV7190/ADV7191 are omitted.
The ADV7190/ADV7191 is operated in 4× oversampling mode.
The 2.4 kΩ resistor, R
SET
, shown in Figure 33 sets the DAC
output current to its minimum full-scale value of 2.16 mA, and
the 600 Ω load resistor produces a full-scale voltage of 1.296 V
at the ADA4430-1 input.
Figure 34 illustrates another reconstruction filter application,
following the ADV7174 video encoder. As in Figure 33, one
ADV7174 output DAC is shown for illustrative purposes, and
the remaining portions of the ADV7174 are omitted.
The 1041 Ω resistor, R
SET
, shown in Figure 34, sets the DAC
output current to its minimum full-scale value of 5 mA, and the
262.5 Ω load resistor produces a full-scale voltage of 1.313 V at
the ADA4430-1 input.
The ADV7174 can produce a maximum full-scale DAC output
current of approximately 35 mA and is therefore capable of
driving the video cable directly; however, as shown in Figure 34,
the ADA4430-1 offers a lower power cable-driving option.
Figure 34 reveals the details of how the ADA4430-1 saves
power when driving video cables with terminations at both
ends. A full-scale level at the DAC output produces 2.626 V at
the ADA4430-1 output, which in turn delivers 17.5 mA into
the cable. In the case shown in Figure 27, the output voltage is
1.313 V, but the current driven into the cable is 35 mA—twice
that required when the ADA4430-1 is used. Therefore, the
ADA4430-1 allows the video encoder to be operated at its
minimum full-scale output current, and it efficiently handles
the cable-driving burden.
2.6kΩ
2.6kΩ
2.6kΩ
1.3kΩ
SAG
GND
V
IN
V
OUT
ADV7190/ADV7191
DAC
DIS
V
S
DISABLE CONTROL
ADA4430-1
1
2
3
4
5
6
2.4kΩ
600Ω
75Ω
75Ω
75Ω CABLE
0.1µF
0.1µF
R
SET
17, 25, 29, 38, 43, 54, 63
34, 48
18, 24, 26, 33,
39, 42, 55, 64
AGND
V
AA
3V
05885-036
×1
Figure 33. Using the ADA4430-1 with the ADV7190/ADV7191 Video Encoder
2.6kΩ
2.6kΩ
1.3kΩ
SAG
GND
V
IN
V
OUT
ADV7174 DAC
V
S
DISABLE CONTROL
ADA4430-1
1
2
3
4
5
6
1041Ω
(931Ω + 110Ω)
75Ω
75Ω
75Ω CABLE
0.1µF
0.1µF
R
SET
2, 10, 18, 25, 27
31
6-9, 11, 12,
17, 19, 26, 40
AGND
V
AA
3
05885-037
262.5Ω
(191Ω + 71.5Ω)
2.6kΩ
DIS
×1
Figure 34. Using the ADA4430-1 with the ADV7174 Video Encoder
