LMH6574 Datasheet, PDF (13/27 Pages) National Semiconductor (TI) – 4:1 High Speed Video Multiplexer

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7 Application and Implementation
LMH6574
SNCS103D – NOVEMBER 2004 – REVISED DECEMBER 2014
NOTE
Information in the following applications sections is not part of the TI component
specification, and TI does not warrant its accuracy or completeness. TI’s customers are
responsible for determining suitability of components for their purposes. Customers should
validate and test their design implementation to confirm system functionality.
7.1 Application Information
The LMH6574 is a high-speed 4:1 analog multiplexer, optimized for very high speed and low distortion. With
selectable gain and excellent AC performance, the LMH6574 is ideally suited for switching high resolution,
presentation grade video signals. The LMH6574 has no internal ground reference. Single or split supply
configurations are both possible. The LMH6574 features very high speed channel switching and disable times.
When disabled the LMH6574 output is high impedance making MUX expansion possible by combining multiple
devices. See Multiplexer Expansion.
7.2 Typical Application
V⁺
IN 0
1
14
8
A0
R_T
A1
IN 1
IN 2
R_IN0
3
R_IN1
5
R_IN2
9
R_T
+
13
V_OUT
-
R_F
12
R_OUT
R_G
11
SD
IN 3
7
10
R_T
R_IN3
EN
2, 4
6
R_T
V^-
Figure 27. Typical Application
7.2.1 Video Performance
The LMH6574 has been designed to provide excellent performance with production quality video signals in a
wide variety of formats such as HDTV and High Resolution VGA. Best performance will be obtained with back-
terminated loads. The back termination reduces reflections from the transmission line and effectively masks
transmission line and other parasitic capacitances from the amplifier output stage. Figure 27 shows a typical
configuration for driving a 75Ω. Cable. The output buffer is configured for a gain of 2, so using back terminated
loads will give a net gain of 1.
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