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TSC2046 Minimum Wait Time Between Power Off and Power On

Jim Warren
Prodigy 250 points
Other Parts Discussed in Thread: TSC2046, TSC2007

Hello.

 

For the TSC2046 touch screen controller, I am trying to determine the minimum time I should wait after powering down the controller, before I can power it back up again. (10 milliseconds, 100 milliseconds, etc…?).  I toggle a GPIO pin connected to "+VCC", pin 1 on the controller to do this.

I looked in the January 2008 data sheet (SBAS265G) but I could not locate this delay value. Can anyone tell me, or better yet provide the page number to a document that contains this information?

 

Many thanks,

 

-Jim

  • 0
    TI__Guru 52115 points

    Hi Jim,

    I will try to find this delay time value for you. I guess you probably cannot you find this information in the datasheet. I may have to ask my colleague who designed this device before for this data, which might take some time.

    In addition, if you put the TSC2046 into the power-down mode, the quiescent current will become very small (3uA in the datasheet). Could you tell me why you want to power on and off this device multiple times?

    Andy

     

  • 0 in reply to Andy Liu (BMS)
    Prodigy 250 points
    Hi Andy,
    We toggle power occasionally due to other components in our system that are prone to ESD. Reseting the TS controller in this manner fixes the issue (in the very rare instance this occurs, not multiple tmes at all actually).
    But yes, please let me know the delay time value you find as soon as possible.
    Many thanks,-Jim
  • 0 in reply to Jim Warren
    TI__Guru 52115 points
    Hi Jim,

    Could you tell me the package information of the TSC2046 device you are using?
    In its datasheet, we have 5 types of TSC2046:
    a) TSC2046IPWR
    b) TSC2046IRGVR
    c) TSC2046IRGVT
    d) TSC2046IZQCR
    e) TSC2046IZQCT

    Andy
  • 0 in reply to Andy Liu (BMS)
    Prodigy 250 points
    Hi Andy,According to our schematic we have the TSC2046IPW.-Jim
  • 0 in reply to Jim Warren
    Prodigy 250 points
    Hi Andy,It is "TSC2046IPWR" specifically...-Jim
  • 0 in reply to Jim Warren
    TI__Guru 52115 points
    Hi Jim,

    I have already discussed this issue with my PE colleagues. This parameter is not listed in datasheet or any internal document, so we are trying to measure this parameter from scratch. However, due to some limitations of our current tester and test program, we are not able to take this measurement easily.

    Our suggestion is that you try multiple tsc2046 samples by yourself. From my perspective, I would say that 1.5s is a safe number.

    Sorry for the late response. I cannot give you a better answer right now.

    Andy
  • 0 in reply to Andy Liu (BMS)
    TI__Guru 52115 points

    Hi Jim

    Finally I have got some feedback from my colleagues who were the designer of the touch controllers. The reason for the wait time between the power off and power on is that the capacitor inside the power-on reset cell does not discharge through a low impedance path when the supply turns off.  Hence, it can take quite some time in order for the power-on reset cell to operate and trigger properly during a re-start of the supply.

    I don't find the POR time for TSC2046. However, below is what you can find in the TSC2007 datasheet.  Since TSC2046 and TSC2007 are very similar devices, I think the same idea could be applied to TSC2046 as well.

    My colleague suggests you take 2 secs of the wait time between the power recycle, which should be plenty at the room temperature. Another note is that "the lower the OFF voltage is, the better! If they can get down below 0.2V or even down to 0.1V quickly and then stay at that voltage for 1.5s that should help. It is a combination out of time and VDD OFF voltage."

    Andy