TS3DV642: 3:1 MUX Solution

Hi, Sreekanth MK

You can cascade multiple TS3DV642 together for a 3:1 MUX solution. There is no specific order to the cascading. But I would recommend adding redriver/retimer on the output to compensate for the Ron and insertion loss of the MUX.

Thanks

David

Hi David,

Thank you for your reply.

Please see the modified architecture below

1) So is this what you recommend??

2) Is there any need of using redriver and retimer together or can i avoid the redriver(TDP158) ??

The insertion loss  and R on of the ports of mux TS3DV642 seems to be asymmetric. In datasheet

Insertion Loss (DC)
– Port A: –0.75 dB
– Port B: –1.0 dB

Intra-Pair (Bit-Bit) Skew
– Port A: 2 ps
– Port B: 6 ps

– R ON
– Port A: 6.5 Ω
– Port B: 8.2 Ω

respectively. So by cascading the output of first TS3DV642  (which is connected to first  two inputs )to Port A of second TS3DV642 (and 3rd input to Port B),i assume the equivalent insertion losses  for channels would be

Channel 1: -1.5dB

Channel 2: -1.75dB

Channel 3: -1.0dB

with this my question is ,

3) Cant we manage the differential impedance to 100 ohms by managing the stackup and trace widths of individual channels for compensating the R on differences.

4) Would the above added attenuation be very critical for HDMI 2.0 compliance / normally  the sinks would have the retimers to compensate these losses?

Regards
Sreekanth MK

Sreekanth MK

The TDP158 is a DP++ to HDMI passive level shifter, so it will not work for this HDMI-only design. If this is a HDMI2.0 design, then we have to use the TMDS181. For HDMI1.4, we can use the TMDS171.

Having two TS3DV642 cascading together would cause HDMI compliance failure on HDMI connector 1 and 2 as you pointed out in your response. So my first proposal is to place the TMDS181 in the front of and behind the TS3DV642 as a way to shield the TS3DV642 Ron and loss from the HDMI compliance.

My 2nd proposal is to place the TMDS181 between the two TS3DV642, but you have to change the PCB trace impedance to take the TS3DV642 Ron into account for the HDMI compliance.

Thanks

David

Hi David,

Ok noted.

Kindly request you to confirm below architectures for the proposed solution 1 and solution 2 suggested by you.

1) Solution 1

2) Solution 2

Regards

Sreekanth MK

Sreekanth MK

Your block diagrams are correct. With the solution #2, you still need to be careful with the PCB routing in order to pass the HDMI compliance. On the output, you may also need common mode choke.

Thanks

David

Hi David,

Thanks for your confirmation. Your suggestions are noted, for CMC i have referred  TI Designs: TIDA-050001 and saw the test results(eye diagram), but the design files referred in page no 18 are broken/missing. Do u have alternate links for the same??

As this package parasitics are critical in these high speed designs do you recommend integrated EMI-ESD solutions as an alternate?

Also you have recommended CMC in output only, does this have any specific reason?

Regards

Sreekanth MK