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TSC2046: what's X-PLATE resistance?

Howard Zou
Genius 12365 points
Part Number: TSC2046

Hi,

1. to measure the pressure we need to know X-PLATE resistance, or both X and Y plate resistance.

But where can we find this parameter, is it hardware determined?

2. For datasheet Figure 8, there is a resistor naming Touch, what does it mean?

And my customer sometimes will read Z1 larger than Z2, which will result in negative Rtouch, what may cause the phenomenon?

  • 0
    TI__Guru 63485 points

    Hi Howard,

    Could you share a datasheet for the touchscreen you're using?  We'll see if we can help locate the required information.

    The "Touch" resistor is supposed to represent where your finger is pressing on the touch screen.  The four-resistor diagram is a large simplification of the touchscreen itself and the 5th resistor was supposed to help visualize where the connections were being made on the touchscreen for the pressure measurement.

    We'll dig in a little more about the negative pressure, but can you confirm that the customer doesn't possibly have the +/- connections mixed up on their touchscreen?

  • 0 in reply to Collin Wells
    TI__Genius 12365 points

    Collin,

    could you please specify the parameters you would like to know about the touchscreen? It's provided by Chinese manufacturer and the parameters are in Chinese.

    We are confident that we haven't mixed up the +/- connection on the touchscreen.

    Below is the parameter we read for the period we touch the same point constantly.

    As you can see, Z2 is 1037 and is bigger than Z1=81 at first, but then the value becomes smaller than Z1. That's strange.

  • 0 in reply to Howard Zou
    TI__Guru 63485 points

    Hello,

    Thank you for confirming the connections.  Can you confirm which of the two methods shown below in the datasheet information that they're using for the pressure measurement?  Looks like it's the 1st option.  

    One thing to note is that the Z1 measurement looks to only return 81.  Do they ever get different values?  

    The "Plate Resistances" will be the total touchscreen resistance values which should be provided in the resistive touchscreen datasheet.