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non-volatile analog switch?

Discussion in 'Electronic Components' started by Jenalee K., Jun 28, 2006.

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  1. Jenalee K.

    Jenalee K. Guest

    To make a non-volatile software programmable DIP switch. Anyone? Like
    those non-volatile digital potentiometers.

    Thanks,
    Jenalee K.
     
  2. Luhan

    Luhan Guest

    Is this switch wired as a circuit element or is it just read by a
    micro?

    Luhan
     
  3. Joel Kolstad

    Joel Kolstad Guest

    How many DIP switches do you need? You can cheat and use those digital pots
    if you don't need too many:
    http://www.maxim-ic.com/appnotes.cfm/appnote_number/238

    If you're looking for something that functions as a switch for routing signals
    around even when no power is available, there are some RF SPDT switches
    that'll still pass a signal from one input to one output or the other with no
    power applied -- they use something like a MOSFET and trap charge to keep the
    channel around without power.

    ---Joel Kolstad
     
  4. Eeyore

    Eeyore Guest

    How about latching relays ?

    Graham
     
  5. If its simply for setting options for a processor, the standard solution
    is an eeprom.

    If you want to actually use the paths through the switch as current
    carriers to other devices, you need to implement that with a processor,
    and still store the settings in the eeprom.

    If there are still any parallel eproms around, you can just use one to
    set the control lines of a cmos switch directly.

    --
    Regards,

    Adrian Jansen adrianjansen at internode dot on dot net
    Design Engineer J & K Micro Systems
    Microcomputer solutions for industrial control
    Note reply address is invalid, convert address above to machine form.
     
  6. Luhan

    Luhan Guest


    Simplest solution. Microcontroller sets control lines on analog
    switches, writes data to internal eeprom, goes to sleep. On powerup,
    reads internal eeprom and sets control lines.

    Luhan
     
  7. Jenalee K.

    Jenalee K. Guest

    Luhan wrote :
    Circuit element. The idea is to not use a micro to have them set on
    power on, but they must be (remotely) configurable at
    installation/maintenance time by attaching a progammer. I do not want a
    dedicated micro because that implicates software development and an
    extra programming operation at production time. I do not want real DIP
    switches because users tend to change their settings and today
    everything has to be software configurable anyway.

    Thanks,
    Jenalee K.
     
  8. Jenalee K.

    Jenalee K. Guest

    Eeyore wrote :
    Latching relays (price?) could work but I'd have to add circuitry to
    read back the actual position.

    Thanks,
    Jenalee K.
     
  9. Jenalee K.

    Jenalee K. Guest

    Joel Kolstad wrote :
    Great info, Joel. I'd thought about using digital pots but their off
    resistance would be too low (up to 200k). And their bandwidth is a bit
    limited. This appnote is a better way.

    Do you have any references for those RF SPDT switches?

    Thanks,
    Jenalee K.
     
  10. Joel Kolstad

    Joel Kolstad Guest

    Hi Jenalee,

    Hmm... I thought I did, but now I'm thinking I was mistaken in how the switch
    actually work. I believe what I looked at was
    http://www.peregrine-semi.com/pdf/datasheets/pe42742ds.pdf, but looking at it
    more closely it always assumes one state when power is removed, so it wouldn't
    work in your application. Sorry for the confusion.

    ---Joel
     
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