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High output 4066?

Discussion in 'Electronic Design' started by simon, Nov 26, 2004.

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  1. simon

    simon Guest

    Anyone help please?

    I'm after a solid state IC (like the 4066 transition gate) whereby I can
    use a microcontroller output to switch a higher voltage output say, up
    to 20v DC, bi-directionally, and is able to pass up to 200mA.

    Does such a product exist? Solid state relays are a little too expensive
    for my application.

    Any advice would be appreciated.

  2. Though you 'rule out' solid state relays, have you looked at the
    Matsushita AQV family?. What you are after, is a 'bilateral switch'. SGS,
    do some, but I don't think the current rating is high enough for your
    application. You can build such a switch yourself, with two FETs, and
    using SMD versions, this would probably be the cheapest route, but the
    little AQV modules are very nice, and not too expensive from some sources.
    Clare do a similar module as well, and something like their CPC1004N,
    might well be a good solution.

    Best Wishes
  3. simon

    simon Guest

    Thanks for the help Roger.

  4. Rich Grise

    Rich Grise Guest

    Is an ordinary reed relay out of the question?

  5. Mark VB

    Mark VB Guest

    Is it really necessary for the outputs to be bi-directional ? If not, you
    can use a darlington-driver like the ULN2803, which has TTL-inputs and can
    drive up to 500mA @ 50V, but afaik they only exist in NPN-version.

    When a bi-directional output is necessary, the easiest way is to build it
    with FET's. I didn't find any bilateral switches for higher currents.

    Btw: There also exist some inexpensive solid-state relays, like the
    S202-series from Sharp.

    Mark Van Borm
  6. simon wrote...
    You can easily roll you own using a pair of small complementary
    20V to 60V MOSFETs. Presumably you're using other '4000 series
    CMOS gates already? If you're using a 20V logic supply, simply
    add an inverter to get the gate signals for your N- and P-channel
    pair. If you're using +/-10V supplies, and need complementary
    +/-10V logic swings for the MOSFET gates, use two '4053 switches
    on the rails - the '4053 has convenient built-in level-shifters.

    If you need advice for small complementary MOSFETs, get back to
    us, but with some of your other constraints spelled out, such as
    do you prefer SMT packages? Etc.
  7. How would you connect regular discrete MOSFETs with no access to the
    substrates or body diodes?

    The PS7113L-1A is < $2 in quantity. That might be another way to go.

    Best regards,
    Spehro Pefhany
  8. Ken Smith

    Ken Smith Guest

    ! !
    ----- -----
    - - - - - - N chan
    ! ! !s s! ! !
    ! -------- !
    ! !
    --------+ +----------
    ! !
    ! -------- !
    ! ! !s s! ! !
    - - - - - - P chan
    ----- -----
    ! !

    You could use just a pair of N-channel devices and one of the photovoltaic
  9. Jim Thompson

    Jim Thompson Guest

    If you have gate drive well in excess of signal you only need one sex.

    ...Jim Thompson
  10. Fred Bloggs

    Fred Bloggs Guest

    Well- he is working with a microcontroller so "up to 20VDC
    bidirectionally" might mean AC and an opto-TRIAC.
  11. Or even a 10-cent MAC97A4 and a resistor, if you want to be like that.

    Best regards,
    Spehro Pefhany
  12. Pooh Bear

    Pooh Bear Guest

    200 mA ?

    Even discrete jfet's will have trouble there. You might get Ron down to
    about 10 ohms. I suppose you could parallel some devices. More complicated
    drive with jfets though. You would need a highish voltage to turn them off.

    What are you switching ?

    Does it need to have a linear 'resistor like' characteristic ?

  13. Rolavine

    Rolavine Guest

    Subject: Re: High output 4066?
    Check out Supertex at the obvious dot com, their HV20220 or other switch
    products may be just what you need.

    Good Luck!

  14. Spehro Pefhany wrote...
  15. Ken Smith wrote...
    The goal was to avoid an opto's higher cost, yet retain the
    '4066 style low-voltage-drop. But if you chose to use a
    photo-MOS device, one bidirectional switch would be enough.

    To answer Spef's question, no special care is needed for two
    complementary MOSFETs if their resistance is low enough. In
    the case of wimpy CMOS transmission gates, substrate switching
    was added to enhance Ron near mid supply, but a pair of power
    MOSFETs would have less of a problem. (Also, as Jim pointed
    out, you could use just one MOSFET if the control voltage was
    large enough and the signal voltage had an appropriate range.)

    E.g., a bss100 and a bss110 in the classic transmission gate
    anti-parallel wiring with 20V logic drive rails would not drop
    below ~ 1.5 ohms Ron with midsupply signals (10V on each gate).
    That's 300mV at 200mA. Hmm, perhaps the O.P. can favor us with
    a more complete specification, so we can understand his required
    signal, logic and supply voltages, and the allowed drop at 200mA.
  16. simon

    simon Guest

    Thanks to all in this thread. I'm still weighing up suggestions but it
    looks like I'll settle for a solid state relay after all.

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