High output 4066?

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.

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 Thanks,
    - Win

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

In message , Roger Hamlett writes

Thanks for the help Roger.

Simon

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

...Jim Thompson

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|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
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I love to cook with wine.      Sometimes I even put it in the food.

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

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"it's the network..."                          "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
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Awkk!

--
 Thanks,
    - Win

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.

--
 Thanks,
    - Win

Or even a 10-cent MAC97A4 and a resistor, if you want to be like that.

Best regards, Spehro Pefhany

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"it's the network..."                          "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com

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

In article , Spehro Pefhany wrote: [...]

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

You could use just a pair of N-channel devices and one of the photovoltaic opto-isolators.

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kensmith@rahul.net   forging knowledge

Well- he is working with a microcontroller so "up to 20VDC bidirectionally" might mean AC and an opto-TRIAC.

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 ?

Graham

Check out Supertex at the obvious dot com, their HV20220 or other switch products may be just what you need.

Good Luck!

Rocky

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.

Cheers, Simon