Question
I want to use AD8152 as a HDMI cross point switch. Can I use the HDMI signal.
Also if it can be used, can I cascade several AD8152s to implement a larger
matrix.
Answer
1. Yes, the AD8152 can be uses to switch the TMDS (high-speed differential)
channels of an HDMI signal. There are four of these signal paths in an HDMI
link (R,G,B and CLK). We have customers who do this. Other means will have to
be used to switch the DDC and HPD signals.
Also, if you want to switch one HDMI input to more than one HDMI output, there
are issues with the HDCP copy protection. We are working on a way to solve
this. Let us know if the customer has interest in this.
2. If you use just one AD8152 (34 x 34), you can make an 8 x 8 HDMI crosspoint
switch for the TMDS signals.
However, you can use four AD8152s to switch 34 x 34 HDMI signals. This does not
require any "cascading". The way to do this is to switch the R signals with one
AD8152, the G with another, the B with a third, and the CLK with a fourth. This
is a pretty large matrix.
How large is the matrix that the customer wants to make? There are some ways to
cascade devices, but it is complicated. The usual approach is to use a single
large crosspoint that is big enough. At this time, the AD8152 is the largest we
have. We are working on a 40 x 40. It's bigger, but not that much.