ADA4432-1BCPZ-R2 datasheet(23/25 Pages) AD

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Data Sheet

ADA4432-1/ADA4433-1

Rev. E | Page 23 of 25

LOW POWER CONSIDERATIONS

Using a series source termination and a shunt load termination on

a low supply voltage with the ADA4432-1 or ADA4433-1 realizes

significant power savings compared with driving a video cable

directly from a DAC output. Figure 56 shows a video DAC

driving a cable directly. Properly terminated, a DAC driven

transmission line requires two 75 Ω loads in parallel, demanding

in excess of 33 mA to reach a full-scale voltage level of 1.3 V.

Figure 57 shows the same video load being driven using the

ADA4432-1 and a series-shunt termination. This requires two

times the output voltage to drive the equivalent of 150 Ω but

only requires a little more than 15 mA to reach a full-scale output.

When running on the same supply voltage as the DAC, this result

in a 74% reduction in power consumption compared with the

circuit in Figure 56. The high order filtering provided by the

ADA4432-1 lowers the requirements on the DAC oversampling

ratio, realizing further power savings. The main source for power

savings realized by the configuration shown in Figure 57 comes

from the low drive mode setting for the ADV7391. This along

with the reduction in the requirement for oversampling (PLL

turned off), and the reduced load current required, results in

significant power savings.

For more detailed information on low drive mode, see the

ADV7391 data sheet.

Figure 56. Driving a Video Transmission Line Directly with a DAC

Figure 57. Driving a Video Transmission Line with the ADA4432-1

75Ω CABLE

75Ω

ADV7391

510Ω

3.3V

RSET

75Ω

300Ω

75Ω

75Ω CABLE

ADV7391

4.12kΩ

3.3V

RSET

ADA4432-1

ADA4432-1BCPZ-R2 Datasheet(PDF) 23 Page - Analog Devices

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