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Help choosing a bi-directional latch — Parallax Forums

Help choosing a bi-directional latch

$WMc%$WMc% Posts: 1,884
edited 2009-01-20 02:39 in General Discussion
Hello All

I'm looking for a 3 state Bi-directional Latch That acts like a dry set of contacts.· By this I mean no polarity on the I/O pins of the Latch.

The HIz state would turn off the I/O's

I can do this with a few chips, But I think theirs an easer way.! ?????

___$WMc%_________

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The Truth is out there············································ BoogerWoods, FL. USA

Comments

  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2009-01-18 02:53
    How much current does the bidrectional I/O have to handle? How many volts? Also, by "latch", I assume you don't want an input to have to hold it on; rather, that it needs to be a clocked part, correct?

    -Phil

    Post Edited (Phil Pilgrim (PhiPi)) : 1/18/2009 3:01:44 AM GMT
  • $WMc%$WMc% Posts: 1,884
    edited 2009-01-18 05:08
    Phil Pilgim

    I'm looking at TTL levels.

    Strictly logic

    0 to 5 volts
    5 to 0 volts

    I've looked at the LM373 and the LM374
    not sure if this is what I need or not

    ___________________$WMc%_________________

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    The Truth is out there············································ BoogerWoods, FL. USA
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2009-01-18 09:14
    The devices you've cited are not bidriectional. You could use a quad bilateral switch, like a 74HC4066, but its control inputs are not latched; you'd have to add a separate latch, if you need latching capability. That's where the '373 (transparent latches) or '374 (D registers) would come in.

    -Phil
  • $WMc%$WMc% Posts: 1,884
    edited 2009-01-20 00:10
    Phil Pilgrim

    Thanks for the info. The 4066 looks like what I'm after...The on state resistance of 80-250 ohm shouldn't be a problem and I don't plan on switching it very fast or very often.


    ___Thanks Again_______________$WMc%___________

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    The Truth is out there············································ BoogerWoods, FL. USA
  • kwinnkwinn Posts: 8,697
    edited 2009-01-20 02:39
    You may want to take a look at the 74LCX16646 from Fairchild if you really need the data to be latched. It has 2 8 bit latches with bidirectional tristate buffers in one package.
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