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DPDT Solid-State Relays - Why so hard to find?

DerStrom8

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Hi folks,

For over a month now I have been trying to find a PCB-mount DPDT (2 Form C) solid-state relay but have had no luck. I know I can use some opto-relays wired in a certain way to do what I need, but I'm curious as to why DPDT SSRs are so rare. In fact, I don't think I've come across any in my searches. Does anyone know of a dedicated DPDT SSR, or will I have to construct one with optos (or other type of switches)?

Thanks,
Matt
 
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Nigel Goodwin

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Probably because solid state 'relays' aren't really a relay at all, just a fairly poor imitation, with lot's of limitations compared to a proper mechanical relay.

Why do you want one?.
 

Tony Stewart

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:wideyed:Why not use the more common dual Half bridge with isolated drivers?

mosfet or ... I.G.B.T.


Can switch up to 1MW loads if you can afford them. From Mitsubishi.


i imagine you must have HV or Inductive reasons for not using a relay, which may be the obvious choice.

In this case, you can design a secondary spark gap switch with fly-leader breakers or HV contactors.

A better question is how many Joules must be switched and at what insulation barrier, and V,I,Z load characteristics?
 
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DerStrom8

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I need to swap two data signals based on a control input. Effectively I need a way to make the following DPDT relay using solid-state parts:



Based on the "position" of the relay, INX will be connected to OUTX or OUTY, and INY will be connected to OUTY or OUTX.
 

crutschow

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I believe they aren't made because of the complexity of the required circuit and the lack of demand for that configuration.

What is the voltage and current, and do you require isolation?
 

jpanhalt

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Can it be done with an inverter and a bilater switch (e.g., CD4016) like this:

upload_2015-7-9_20-20-4.png

John
 

Nigel Goodwin

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Most Helpful Member
I need to swap two data signals based on a control input. Effectively I need a way to make the following DPDT relay using solid-state parts:



Based on the "position" of the relay, INX will be connected to OUTX or OUTY, and INY will be connected to OUTY or OUTX.
So you want a CMOS switch, NOT a relay :D

Check out the various CMOS switches - the 4066 is the most common one.
 

DerStrom8

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Most Helpful Member
So you want a CMOS switch, NOT a relay :D

Check out the various CMOS switches - the 4066 is the most common one.
Ok, I guess my terminology was wrong. It functions like a relay, but is technically just a switch. This is MUCH closer! I actually think the NX3L2467 is exactly what I need!

Thanks folks!
 
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DerStrom8

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DerStrom8

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Are these analog signals? Any reason not to use a multiplexer?
They are both digital signals. I need to be able to swap their paths, hence the DPDT relay diagram I added in Post #4
 

ericgibbs

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They are both digital signals. I need to be able to swap their paths, hence the DPDT relay diagram I added in Post #4
hi,
Look at this IC, CD4503, its a tri-state non inverting buffer.
E
 

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DerStrom8

Super Moderator
Most Helpful Member
hi,
Look at this IC, CD4503, its a tri-state non inverting buffer.
E
Thanks Eric, but I don't think that's quite what I'm looking for. The second one you posted is, but it uses more components. I'll probably stick with the NLAS44599. It does exactly what I need it to.

Thank you everyone for the help!
Matt
 

ChrisP58

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Also look at the CD4052 and CD4053 CMOS analog switches.
Similar parts #s are 74HC(T)4052, 74HC(T)4053.
 

jpanhalt

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Thank you for letting us know it is digital (post#12). Why not use a small, 8-pin MCU?

John
 

DerStrom8

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Most Helpful Member
Thank you for letting us know it is digital (post#12). Why not use a small, 8-pin MCU?

John
Due to the nature of this project, the fewer MUCs the better. Bidirectional switches are definitely the way to go as they simply pass the signals.
 

jpanhalt

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Most Helpful Member
I don't understand that logic. Why is analog (like the CD4016) better than digital when dealing with digital signals? Please expand on that reasoning.

John
 

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