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TS3DV642: Using TS3DV642 for analog signal switching before an ADC

Ahmed Noeman
Expert 3500 points
Part Number: TS3DV642
Other Parts Discussed in Thread: TS3USB221A-Q1

Hello,

I got some customer questions related to TS3DV642. the cusotmer is intending to use the HDMI switch in an industrial application.

  1. The TS3DV642 mux data sheet examples all show AC coupling on the signal paths with plot data down to 1 MHz signaling – is this due to the application of video, does the switch have limitations on DC operation?  
  2. The switching turn on time is rated as 100 usec maximum, equivalent to 10% of our 1 msec overall scan time.   Why so much slower than prior analog (ADI, Maxim) switches?    Since we are going into a high impedance, is there data on equivalent switch resistance vs time that would allow us to cut this time down in our switch to measure set up?
  3. This part is rated up to 85C, is there any equivalent for the automotive 105C market?

Kind Regards,

  • 0
    TI__Mastermind 45350 points

    Ahmed,

    1.The TS3DV642 mux data sheet examples all show AC coupling on the signal paths with plot data down to 1 MHz signaling – is this due to the application of video, does the switch have limitations on DC operation?  

    The TS3DV642 device DC limitation is that it cannot pass a negative voltage.  One of the biggest mistakes desiging with the TS3DV642 is placing the AC coupling caps on both sides of the switch eliminating the common mode voltage for AC signals.  Other than that as long as the DC voltage and current are withing the specified values in the datasheet you shouldn't have an issue. 

    2.The switching turn on time is rated as 100 usec maximum, equivalent to 10% of our 1 msec overall scan time.   Why so much slower than prior analog (ADI, Maxim) switches?    Since we are going into a high impedance, is there data on equivalent switch resistance vs time that would allow us to cut this time down in our switch to measure set up?

    The TS3DV642 device has a charge pump that is turned off in low power mode.  The switch turn on time in the 100us range is the time it takes the device to turn on when you take the device out of low power mode which is predominantly driven by the time it takes for the charge pump to turn on.  Once the switch is on scanning between channels is the tswitch spec ~20us. 

     

      Do you have an example of the ADI switch that has the faster turn on time?  We are looking to build new switches and can include this feature in future products if it is desirable. 

    3.This part is rated up to 85C, is there any equivalent for the automotive 105C market?

    At this time there is not an automotive version of the TS3DV642.  We are looking to gather enough business to go through the testing process but have not found enough need yet for this feature. 

     

    We do have other high speed 1:2 switches like the TS3USB221A-Q1 device but would need 6x of them to get 12 channels.  Is this an option for you?

     

    Thank you,

    Adam