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Pin protection diode — Parallax Forums

Pin protection diode

CenlasoftCenlasoft Posts: 265
edited 2008-12-31 04:46 in General Discussion
Hello,
I using an sx28 to send out a square wave to a tank circuit (coil + capacitor). Do I need a diode to protect my pin?
Thanks,
Curtis

Comments

  • LeonLeon Posts: 7,620
    edited 2008-12-30 17:27
    Only if the coil is an iron-cored part, like a solenoid. If it's a high-frequency tank circuit you should be OK. Is it some sort of transmitter?

    Leon

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    Amateur radio callsign: G1HSM
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  • CenlasoftCenlasoft Posts: 265
    edited 2008-12-30 19:28
    The coil is a 90 uH coil and is being used as a sensor for eddy currents. The resonance frequency of the circuit is 530 khz.
    Thanks,
    Curtis
  • Beau SchwabeBeau Schwabe Posts: 6,568
    edited 2008-12-31 04:46
    Cenlasoft,

    You should be ok without a diode, but it depends on what this part of the circuit looks like... is there anyway you can post a schematic?

    Is this a parallel or series resonant circuit? A series resonant circuit will look like a "short" near the resonant frequency in which case I would place a small resistor on the I/O pin, while a parallel resonant circuit will look like an "open circuit" near the resonant frequency.

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    Beau Schwabe

    IC Layout Engineer
    Parallax, Inc.
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