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TSC2046E: PCB Layout

Riccardo Molinari
Prodigy 60 points
Part Number: TSC2046E

Hello,

In this moment I am interesting to use the SPI Resistive Controller TSC2046E.

For use this controller I need some PCB layout information.
In the application report SLAA560 I have found the indication that "Connect the analog input pin AUX (or AUX IN, or IN), or V BAT to ground if not used."

It is correct connect this pin to ground through a capacitor 10uF 16V?

I want to use the internal TSC2046E voltage reference; It is correct connect also the V REF pin to ground with the same capacitor 10uF 16V?

Lastly if I not used the pen interrupt output (PENIRQ\) and the busy output (BUSY) Have I to connect them to ground or to the power supply? Can I use the same capacitor 10uF 16V?

Thank you very much in advance for your attention.

Best Regards

  • 0
    TI__Mastermind 20085 points
    Hello Riccardo,

    Welcome to E2E, thanks for your interest in our products.
    It is not necessary to use a capacitor to tie the analog pins to ground.
    Talking about voltage reference a bypass capacitor is generally not needed on the Vref pin because the internal reference is buffered by an internal opamp, but that depends on your application.
    We always recommend using PENIRQ and Busy pins to ensure the device right operation.

    Best Regards
    José Luis Figueroa
    Application Engineer
  • 0 in reply to José Luis
    Prodigy 60 points

    Hello José,

    thank you very much for your welcome in the E2E and for your reply.
    I have followed your suggestion and I have connected directly the analog input pin to ground.

    Regarding the Vref, even if I have intention to use the internal voltage reference and the differential mode for the touch screen detection, I have decided to connect it to the power supply (3.3V) anyway in way to use it in case we want detect the temperatures.

    Finally I have connect the PENIRQ signal and the BUSY signal to microcontroller GPIO in way to manage well the controller operation.

    I have another question; to avoid problem with the EMI noise in the datasheeet we suggest to add a filter capacitors (100nF) from Y+, Y-, X+ and X- pins to ground.
    If I will put between the same pins and ground Bi-Directional TVS Diode, for example like NXP PESD5V0L1BA, can be a problem for the signal in the Y+, Y-, X+ and X- lines?

    Thank you for your additional attention.

    Best Regards
    Riccardo Molinari

  • 0 in reply to Riccardo Molinari
    TI__Mastermind 20085 points
    Hi Riccardo,

    As the last line of defense, you should add the capacitors and I don't think that TVS diodes can cause a problem at the signal lines.
    I recommend you to review the ESD Protection Considerations section of the SLAA560 application report, here you can find information about this.

    Best Regards
    José Luis Figueroa
    Application Engineer
  • 0 in reply to José Luis
    Prodigy 60 points

    Hi Josè

    thank you very much for your kindly reply.

    Best Regards and have a nice day.

    Riccardo