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, RSET, 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, RSET, 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

VIN

VOUT

ADV7190/ADV7191

DAC

DIS

VS

DISABLE CONTROL

ADA4430-1

1

2

3

4

5

6

2.4kΩ

600Ω

75Ω

75Ω

75Ω CABLE

0.1µF

0.1µF

RSET

17, 25, 29, 38, 43, 54, 63

34, 48

18, 24, 26, 33,

39, 42, 55, 64

AGND

VAA

3V

×1

Figure 33. Using the ADA4430-1 with the ADV7190/ADV7191 Video Encoder

2.6kΩ

2.6kΩ

1.3kΩ

SAG

GND

VIN

VOUT

ADV7174 DAC

VS

DISABLE CONTROL

ADA4430-1

1

2

3

4

5 6

1041Ω

(931Ω + 110Ω)

75Ω

75Ω

75Ω CABLE

0.1µF

0.1µF

RSET

2, 10, 18, 25, 27

31

6-9, 11, 12,

17, 19, 26, 40

AGND

VAA

3V

262.5Ω

(191Ω + 71.5Ω)

2.6kΩ

DIS

×1

Figure 34. Using the ADA4430-1 with the ADV7174 Video Encoder