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SN3257-Q1: Can 2:1 automotive SN3257-Q1 switch support NTSC video with 75 ohm output?

Part Number: SN3257-Q1
Other Parts Discussed in Thread: TMUX6219-Q1

e2e, 

I'm looking for a video selector for NTSC video signals.  Would you please recommend an automotive qualified multiplex to support it with the requirements below? 

Requirement

  • Signal format is NTSC
  • 2 Input, 1 output.
  • 75Ω Output
  • Automotive qualified

Thank you,

Adam

  • Hi Adam,

    NTSC signals need the potential to pass a small negative voltage (seems to be around -300mV), so I would recommend the TMUX6219-Q1 which allows dual rail operation (+/-4.5V) and has a low RON spec. Bandwidth is 40MHz which should also cover this spec.

    One thing I would like to try to clarify is if there is any common mode signal this is referencing? The part I recommended will work up to +/-18V dual supply or 36V single supply, so if it isn't referencing any other common mode voltage, this should be fine. Otherwise, we would need to know that common mode signal to recommend the correct part.

    Thanks!

    Bryan

  • Bryan, 

    What device would you recommend if there is a common voltage eliminating the need to support signal switch below ground? 

    Thank you,

    Adam

  • Hi Adam,

    If that is the case, the TS5A3159-Q1 would be a good choice. Has very low RON (1ohm), is automotive qualified, and has a small footprint. In addition, it has bandwidth support up to 100MHz which is plenty for this application.

    Thanks!

    Bryan