ADV3219/ADV3220

Rev. 0 | Page 16 of 20

THEORY OF OPERATION

The ADV3219/ADV3220 are dual-supply, high performance 2:1

analog multiplexers, optimized for switching between multiple

video sources. High peak slew rates enable wide bandwidth oper-

ation for large input signals. Internal compensation provides for

high phase margin, allowing low overshoot and fast settling for

pulsed inputs. Low enabled and disabled power consumption make

the ADV3219 and ADV3220 ideal for constructing larger arrays.

The multiplexer is organized as two input transconductance

stages tied in parallel with a single output transimpedance stage

followed by a unity-gain buffer. Internal voltage feedback sets

the gain. The ADV3219 is configured as a gain of 1, whereas the

ADV3220 uses a resistive feedback network and ground buffer to

realize gain-of-2 operation (see Figure 56). The ground reference

for the ADV3220 is taken from the exposed pad of the package.

To minimize spurious signals on the output, tie the exposed pad

to a low inductance, quiet ground plane.

V+

V–

IN0

V+

V–

IN1

V+

V–

GND

×1

1k

Ω

1k

Ω

OUT

Figure 56. Conceptual Diagram of ADV3220

When not in use, place the OUT pin in a low power, high

impedance disabled mode via the EN logic input. This mode

provides a wideband high impedance on the OUT pin that is

useful when paralleling multiple ADV3219/ADV3220 devices

in a system to create larger switching arrays.

Switching between the inputs is controlled with the SELECT

logic input, with IN0 selected when the SELECT line is a logical

low and IN1 selected when the select line is a logical high. When

EN is a logical low, the output is enabled and connected to one

of the two inputs depending on the state of the SELECT pin.

When EN is a logical high, the output is placed in a high

impedance mode.

When not in use, the output can be placed in a low power, high

impedance disabled mode via the EN logic input.