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TPS65070: Some questions

Ryu Yamashita
Genius 3620 points
Part Number: TPS65070

Tool/software:

Hi team,

I don't understand the difference between the value of “Plate resistance”, the value of “Resistance between plates contact” and the value of “Resistance between plates pressure”.
What is the definition of each?

I am planning to use a touch panel with 274Ω to 640Ω in the X direction and 183Ω to 428Ω in the Y direction.
Can I use this one?

If not, is there any other recommended device or circuit solution?

Best Regards,
Ryu.

  • 0
    TI__Genius 9417 points

    Hi Ryu, 

    Thank you for reaching out on E2E. Please be aware that TPS65070 is one of our older devices, so support may be limited.

    Plate resistance is referring to the resistance along the X or Y direction. 

    Resistance between plates contact/pressure is referring to the resistance in the Z direction, between the two plates (R_contact in the diagram below), 
    This is used to measure the pressure on the touch screen. Contact and Pressure should mean the same thing in this context. 

    The resistances of your touch panel fit within the specs of the X and Y plate resistances, so this will be fine. 
    R_contact is typically calculated depending on the pressure applied to the screen, this may not be explicitly listed as a spec for the touch panel. 

    The TPS65070 is a unique device that is a PMIC (Power Management IC) that implements a touch screen interface feature,
    if you are interested specifically in more touch screen controller options, I would recommend taking a look at the TSCxx products,

    If you have further questions about these devices, I would advise posting another forum question under one of these part numbers. 

    Best Regards, 
    Sarah

  • 0 in reply to Sarah Lao
    Genius 3620 points

    HI Sarah,

    Thanks for the reply.
    I understood.
    Please tell me one more point.
    The minimum value for plate Y is 200 ohms, but the minimum value for this touch panel is 183 ohms.
    Is this a problem?

    Best Regards,
    Ryu.

  • 0 in reply to Ryu Yamashita
    TI__Genius 9417 points

    Hi Ryu, 

    Apologies, I did not notice that earlier. 

    I want to say there is minimal risk here, since typical value will fall within the acceptable range. 

    However, this may be a question better directed towards the controller experts who handle the TSC products, as I can only speak on the operation of PMICs.
    I am unsure of the exact risk here.
    Apologies if I cannot help any further, I may redirect this question to the TSC product line,
    or I ask that you create a separate thread under the TSC part number to confirm with them. 

    Best Regards, 
    Sarah

  • 0 in reply to Sarah Lao
    Genius 3620 points

    HI Sarah,

    Thanks for the reply.
    Can you forward the following questions to the TSC team?
    If the resistance value is not enough, can it be compensated by adding a series resistor or other means to make it work without problems?

    Best Regards,
    Ryu.

  • 0 in reply to Ryu Yamashita
    TI__Genius 9417 points

    Hi Ryu, 

    Redirecting your question to the TSC team, thank you for your patience.

    Best Regards, 
    Sarah

  • 0 in reply to Sarah Lao
    TI__Mastermind 27110 points

    HI Ryu,

    A series resistor can be added to meet the impedance requirement. Meeting the minimum requirement will the reduce noise on the XY lines for a more accurate trigger/touch registered with the TSC device you choose.