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IR Detector, Parallax P/N 350-00014 — Parallax Forums

IR Detector, Parallax P/N 350-00014

Alexander (Sandy) HapgoodAlexander (Sandy) Hapgood Posts: 360
in Propeller 2
This detector is powered by 5 VDC. What precautions should I take when connecting the output of this part to my Propeller II Evaluation Board, Rev. C? Don't want to let the magic smoke out, at least not this early in the game.

Thanks,
Sandy

Comments

  • JonnyMacJonnyMac Posts: 9,104
    edited 2020-08-13 19:47
    You'll be fine: There is a 30K pull-up to 5v on the [open-collector] output of the detector which limits the current through the pin protection diodes to a very safe level. I connected directly to my Eval board when developing my SIRCS RX object for the P2.
  • Alexander (Sandy) HapgoodAlexander (Sandy) Hapgood Posts: 360
    edited 2020-08-14 00:40
    Excellent! Thanks Jon.

    I couldn't find any information about pin protection diodes for the P2. I suppose it's buried in there somewhere.

    Sandy
  • JonnyMacJonnyMac Posts: 9,104
    To be candid, Sandy, I was making the assumption that they're similar to the P1.

    (5v - 3.3v - 0.3v) / 30K = ~47uA; the protection diodes on the P1 have a spec of 500uA.
  • Alexander (Sandy) HapgoodAlexander (Sandy) Hapgood Posts: 360
    cgracey wrote: »
    The pins that we've designed are 3.3V-only. I'm pretty sure that the OnSemi 180nm process has provisions for making 5V-tolerant pads, but not 5V-output pads. At any rate, we are quite committed at this point to our 3.3V pad, which has lots of analog stuff in it and is quite wed to 3.3V.

    Not a definitive word as it was from another thread and the conversation may have turned to 5V output.
  • Cluso99Cluso99 Posts: 18,069
    Alexander (Sandy) Hapgood wrote: »
    cgracey wrote: »
    The pins that we've designed are 3.3V-only. I'm pretty sure that the OnSemi 180nm process has provisions for making 5V-tolerant pads, but not 5V-output pads. At any rate, we are quite committed at this point to our 3.3V pad, which has lots of analog stuff in it and is quite wed to 3.3V.

    Not a definitive word as it was from another thread and the conversation may have turned to 5V output.
    The IO pads and surrounding area was designed by Parallax years ago. It is not an OnSemi pad.
  • YanomaniYanomani Posts: 1,524
    edited 2020-08-14 05:55
    Hi all

    IMHO, you could use OnSemi's latch-up test results as posted by Chip (nine month ago! Wow...) as a landmark, then peruse "New P2 Silicon" thread back and forth, in order to get the most valuable information about P2 pins, including overvoltage-related limits.

    Lots of good stuff, as always! :lol:

    https://forums.parallax.com/discussion/comment/1482107/#Comment_1482107

    Hope it helps

    Henrique

    P.S. To be clear, applies to both Rev.B and C silicon (not sure of Rev.A limits; IIRC they were not didn't got screened to this point).
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