Book Analog Interfacing to Embedded Microprocessors
The Analog Devices
ADV7120 is a triple 8-bit video DAC designed for video use. The part contains
3 DACs for the RGB (red green blue) video signals. The ADV7120 also has
SYNC and BLANK inputs that force all three outputs to the sync and blank-
ing levels, respectively (Figure 6.16). Other specialized DACs include audio
parts with built-in volume control and mute functions, and DACs that are opti-
mized for use in voice transmission systems such as telephones.
Digital Potentiometers
Although a DAC can provide a voltage or current output for control, some-
times a design calls for a variable resistance. Typical examples would be a
volume or tone control in a stereo, or gain control in an opamp circuit. In
these cases, a digital potentiometer is often the ideal solution. Like a DAC, a
digital potentiometer takes a digital word from a microprocessor, but it con-
verts it to a resistance instead of a voltage.
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