An alternate approach would be to tie the outputs directly

together and let all devices share a common back termina-

tion resistor in order to alleviate the gain error issue above.

The drawback in this case is the increased capacitive load

presented to the output of each LMH6572 due to the off-

state capacitance of the LMH6572.

EXPANDING THE MUX

It is possible to build higher density MUX’s by paralleling

several LMH6572’s. Figure 4 shows a 4:1 RGB MUX using

two LMH6572’s:

If it is important in the end application to make sure that no

two inputs are presented to the output at the same time, an

optional delay block can be added, prior to the ENABLE (EN)

pin of each device, as shown. Figure 5 shows one possible

approach to this delay circuit. The delay circuit shown will

delay ENABLE’s H to L transitions (R

won’t delay its L to H transition.

20109617

FIGURE 3. Multiplexer Input Expansion by

Combining Output

20109618

FIGURE 4. RGB MUX USING TWO LMH6572’s

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