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VGA switching with TS5V522C

Oliver Stein
Prodigy 30 points
Other Parts Discussed in Thread: TS5V522C, SN74CBT3257C, TS3V712E, TS3V713EL

Hello!


I'm currently doing a school project where we need to switch VGA signals. I have a few TS5V522C circuits and as I understand they are perfect for the job. My only problem is that I'm not understanding where the HSYNC and VSYNC signals go in the example in the datasheet figure 1. I'm a total beginner at VGA signals, but as far as I understand the example does exactly what we want to achieve, which is a switch of either 1:2 or 2:1. What confuses me is that in the example the HSYNC and VSYNC signals pass through the TS5V522C, but it has no pins for V or HSYNC, only RGB and SCL/SCA. Should the V- and HSYNC signals go to these pins or am I missing something? Some clarity on what goes to what pin here would be very helpful!

Also, do I need the SN74CBT3257C multiplexer if I only want to switch the video signals? Or are the SDA and SCL necessary for this as well?

Thanks for reading!

Oliver

  • 0
    TI__Mastermind 45420 points

    Oliver,

    The TS5V522C is a 5 channel 1:2 SPDT switch.  This means the TS5V522C can only switch 5 signals, but you are asking about switching 7 signals (R, G, B, SDA, SCL, HSYNC, and VSYNC.)   If you use the TS5V522C you will need an additional IC to switch all 7 signals

    I would recommend using the TS3V713EL (if you need level shifting) or TS3V712E (if you do not need level shifting) which can switch all 7 signals with 1 IC. 

    Thank you,

    Adam

  • 0 in reply to Adam Torma
    Prodigy 30 points

    Hello Adam,


    Thanks for your answer! I think you misunderstood my question however. I am only interested in switching the 5 signals R, G, B HSYNC and VSYNC (as far as I understand that's all you need for VGA). But in the pinout, pins 16 through 23 are for SCA and SCL. Have you seen the example from the datasheet? http://www.ti.com/lit/ds/symlink/ts5v522c.pdf In figure 1 they have a diagram showing an example how one could use it.

    Here they describe what I want to achieve, but they also have some extra component for SCL and SDA, the CBT3257C, which I also have.


    But if the TS5V522C is just a 5 channel spdt, maybe I can input anything from the VGA signal to any pin? I just don't understand which pins get the HSYNC and VSYNC signals in the example.


    Oliver

  • 0
    Prodigy 30 points
    I feel stupid now, but I managed to find the information in the datasheet. So, in short, the answer is that yes, the HSYNC and VSYNC signals go into the SCL and SCA pins of the TS5V522C. I still don't know what SDA and SCL would be used for, but I don't think I need them for just displaying the VGA signal. So, unless I am mistaken, this switch is all you need for VGA signals if you only care about the video (R, G, B, HSYNC and VSYNC).
  • 0 in reply to Oliver Stein
    TI__Mastermind 45420 points

    Oliver,

    You shouldn't feel stupid because you arrived at an answer you needed to move forward.  That is what the forums are all about. 

    All 5 of the signal paths in the TS5V522C are the same, so you are correct, you can place any signal on any pin. 

    Adam