AD8074Z-EVAL Analog Devices Inc, AD8074Z-EVAL Datasheet - Page 11

• Manufacturer Part Number: AD8074Z-EVAL
• Description: BOARD EVAL FOR AD8074
• Manufacturer: Analog Devices Inc

Specifications of AD8074Z-EVAL

• Main Purpose: Video, Amplifier, Triple
• Embedded: No
• Utilized Ic / Part: AD8074
• Primary Attributes: Buffer, 600MHz (200 mV), 1600 V/us Slew Rate
• Secondary Attributes: +/- 4.5 ~ 5.5 V, < 30 mA
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Triple Video Multiplexer
The AD8074 and AD8075 each have an output-enable function
that can be used to disable the outputs and put them in a high-
impedance state. Usually, for a unity-gain device, it is relatively
easy to provide high disabled impedance, because the feedback
path is from the output to a high-impedance input. However, for a
non-unity-gain part, the feedback provides a resistive path to
ground. This will usually dominate the disabled output imped-
ance, and make it a much lower value than the unity-gain device.
The AD8075 has an internal buffer that provides a low-impedance,
ground level output that terminates the feedback path during
enabled operation. In the disabled state, both this buffer output
SOURCE 1
SOURCE 2
SEL1/SEL2
R
G
B
R
G
B
75
75
75
75
75
75
25 F
25 F
+
+
+5V
+5V
25 F
25 F
+
+
0.1 F
0.1 F
–5V
–5V
+5V
+5V
0.1 F
0.1 F
0.1 F
0.1 F
AD8075
AD8075
–5V
–5V
+5V
+5V
and the amplifier output are disabled to a high impedance to
provide a high-impedance disabled state.
To construct a multiplexer, the outputs from one or more devices
are connected in parallel and only one device is enabled at a
time while all of the others are disabled. The two sets of inputs
are applied individually to each of the separate device inputs.
Figure 4 shows the circuit details for this function. The first RGB
Source 1 is input to the first AD8075. Each of the individual
signals is terminated to ground with 75 Ω to provide proper
termination for the input cables. In a similar fashion, the Source
2 signals are input to the second AD8075.
0.1 F
0.1 F
0.1 F
0.1 F
–5V
–5V
OE
OE
0.1 F
0.1 F
75
75
75
75
75
75
AD8074/AD8075
G
R
B
OUTPUT