LMH6585VV National Semiconductor, LMH6585VV Datasheet - Page 16

• Manufacturer Part Number: LMH6585VV
• Manufacturer: National Semiconductor

Specifications of LMH6585VV

• Array Configuration: 32x16
• Number Of Arrays: 1
• Screening Level: Industrial
• Pin Count: 144
• Package Type: LQFP
• Power Supply Requirement: Dual
• Lead Free Status / RoHS Status: Supplier Unconfirmed

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CHANNEL VARIATIONS
The LMH6584/LMH6584 crosspoint switches have a very
large number of possible channel combinations. There is
some systematic variation in channel performance. Parame-
ters such as bandwidth and distortion have a range of values
depending on which channel combination is selected. The
Because the inputs are the dominate factor in channel band-
width it is possible to adjust the bandwith of the slower inputs.
One method of increasing input bandwidth is with the use of
buffers as illustrated in Figure 1. A simpler method using a
single inductor is shown below in Figure 7.
FIGURE 7. Use of Termination Inductor to Increase
Bandwidth
FIGURE 6. Bandwidth Variation over Channel Combinations
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variation in bandwidth over all possible input/output combi-
nations is shown in Figure 6. One particular pattern to note is
that input channels 0 through 3 are slower than all other in-
puts. The use of input buffers as illustrated above can help
equalize channel bandwidths.
The use of termination inductors can also be used when two
crosspoints are used back to back for output expansion. The
difference in input speeds between the opposing chips poses
an additional challenge, especially if the channels that are
connected together have very different performance. When
connecting a slower channel (channels 0 to 3) to a faster
channel the circuit shown in Figure 9 is recommended. In this
case the inductor value is chosen to bring up the slow channel
bandwidth, while the resistor R
mance of the two channels. Larger values of R
FIGURE 8. Termination Inductor Bandwidth
Enhancement Using Input 0
M
is used to match the perfor-
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M
will slow