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TS5V330: ts5v330 about resistor input and output

Part Number: TS5V330
Other Parts Discussed in Thread: LMH6574,

Hello Rami,

Well finally I got the part, in first instance it worked fine, however i only tried with only one signal, and it did the switching correctly, but when i put 2 signals one in each input, the resulting image is with a ghost from the other signal, is like an interference among them, and after a while working the parasite signal was worse, even the main signal was corrupted and almost unseenble.

What do you recomend for this?

PD i saw also this multiplexer LMH6574, can you get an Functional Block Diagram with resistor and capacitors value to be tested?

Thanks

  • Hey Eduardo,
     
    Sounds like some crosstalk or some isolation issue could be the problem here.
    What are the characteristics of the signals being passed through? (i.e. voltage, frequency) 
    Has your board layout changed from when we discussed in the previous thread? Could you provide any changed you may have made? 

    For the LMH6574, I believe you're referring to the block diagram in section 7.1. I'm not especially familiar with this device as, although it does have a multiplexer integrated, it's outside our immediate portfolio. I'm looping in some one who can help you more here.
    In the meantime, however, it looks like the datasheet provides the RIn and Rout values for you in the electrical characteristics table under Miscellaneous Performance. Additionally, in the layout guideline (section 10) there seems to be a note on the bypass capacitors. I would look into these and see if you can construct the block diagram from what's giving. Just a couple things to look into.


    Thanks,
    Rami Mooti

  • Hello Eduardo,

    Not quite sure what you mean on getting this tested, the datasheet electrical characteristics & figures are meant to display the performance of the device. In regards to the resistors & capacitances used in the block diagram, as Rami mentioned you can use the layout guideline for bypass capacitors. In regards to Rin & Rout, these are set to 75-ohms with the assumption of interfacing with video signals but can be adjusted based off the application. In regards to RF you can use figure 27 to determine RF based off of gain. 

    To clarify on the Rin & Rout values under Miscellaneous performance, these are the impedances of the device itself and do not correspond to the external resistors & caps shown in the block diagram.

    Best,

    Hasan Babiker

  • Hello Rami, thank you for your answer, i was very busy in these days.

    Well the pcb is the same, but works fine with one signal but not with 2, internally they should have not connection between them so i am a little confuse here. I saw the diagram but at the output there some resistors with not value, so i dont know this to create a pcb and test it.

  • Hello Hasan thank you, i am not an expert to "read" this, can you help me, in fact, i am using 75 Ohm system, so it should works but to test this IC i want to creat the PCB and put the right values for Capacitors and Resistors,

    Hoping you can help me to identify this values,

    Best Regards.

  • Hey Eduardo,

    Which diagram are you talking about here when you say "I saw the diagram but at the output there some resistors with not value"? 

    Could you provide information about the characteristics of the signals being passed through to see if we can pinpoint this issue? (i.e. voltage, frequency) 

    Thanks,
    Rami Mooti

  • Hello Eduardo,

    I agree an idea of your signals would also help to determine whether the LMH6574 is appropriate here. For the amplifier in the device, would you like to configure this to a gain of 2 to account for the attenuation as a cause of terminating your input? What is the output load here?

    Best,

    Hasan Babiker

  • Hello Hasan, thank you for your answer, well let my try to explain what i want to do:

    My idea is to conmute the video signals from differents equipments as STB, DVD, thru composite video signals (Yellow, White and Red RCA connectors) to a common TV, this IC will be controlled by arduino. this is basically my idea, in the first moment the TS5V330 was a perfect IC however in the test doesn't work properly, so i am looking for another one, in this case I found also this multiplexer for analog video LMH6574, the problems i dont have an idea how to create the pcb correctly, so I can test his performance before create the final PCB with my project, because it is more big that only video, this will be just a part of it.

    I dont know if I explain myself correctly.

  • Hello Rami, well this check the diagram, my question is about Rf and Rg because i assume Rin and Rout will be 75 Ohm resistor right? and Rt will be 10K to provide gnd to the input when they are open

  • Eduardo,

    It looks like you attached an image that didn't quite go through. Do you mind giving it another go?

    In the meantime, do you have any information regarding the actual signal level and frequency you're trying to pass through? video signal frequency can vary and i'm looking to confirm that the frequency and voltage that you're using don't exceed specs. At higher frequencies you'll also need to be more cautious about your spacing of your traces on your PCB for isolation. This information would be useful to us to help you.

    Thanks,
    Rami Mooti

  • Hello Rami, yes the image is attached again.

    Well as i said, in the first moment only with 1 signal worked fine, but when i put the other the problem started. but the quality of the signal (only one) was clear and nice, no issue.

    I am only have for video is about 500mV and 6.5mA, frequency I dont have it

  • Eduardo,

    When you say only 1 signal works fine until the second signal, is this 1 signal on S1A and then the second signal placed on S2A or are you adding these across channels, as in another signal to S1B?
    Right now, i'm understanding it as you've applied a signal to S1A and it appears present just fine on DA. Then when S2A is fed a signal, you see a problem where one of the two lines looks good but the other one has some degradation when it is selected. If this is correct could you switch the sources, as in put the signal that is normally at S1A onto S2A and vice versa. 


    Additionally, are there any screen captures of the signal? or are you just looking at a screen monitor to see whether it's working or not? 

    Thanks,
    Rami Mooti 

  • Hello Rami, well when i tried this again my source got damage and also my IC was damaged too, so I couldnt try this again, however i got the LMH6574MAX IC, i would like to know a circuit that can works to test it, can you help me with this please? 

    LMH6574MAX
  • Hello Eduardo,

    You can begin with the block diagram in the datasheet of the LMH6574. For Rin = Rout = 75-ohm for termination (you mentioned you are using 75-ohm system), RF = RG = 575 ohms for gain of 2, and depending on rise time of digital signal & distance they need to travel you may or may not want to apply termination for RT. 

    Best,

    Hasan Babiker

  • Hello Hasan, thank you for answer, my sorry i was very busy, ok will check this, however for resistor a 575 Ohm is not a commercial value, can i use 560 instead?

  • Hello Eduardo,

    It would be better to go up rather than down in resistance. Since this is a current feedback amplifier, RF has a large effect on the stability of the device. While lowering the resistance may add more ringing (probably not enough to go unstable just going from 575 to 560) adding a larger resistor will just lower the bandwidth slightly and increase noise.

    Best,

    Hasan Babiker