Switch 12-28 VDC and VAC up to 1-2A and not use relay?

[nardev]

Hey guys, i need to switch on/off, nothing fast. Nothing below 1s at a time, to connect 12-28 VDC/VAC but to avoid using relays.

Any suggestions?

And jes, the controller which i use is 5V logic so, i wold prefer that it works with 5V logic.


thnx

[Kim Christensen]

You could use a pair of back-to-back MOSFETs and driver circuitry. Essentially building your own solid state "relay"...
Something like this, but with beefier FETs

[nardev]

How about Thyristor? I should also mention it's a coil that i have to turn on/off.

I just never used this in the application, i have no idea about pros/cons. Is there something important to say about Thyristor?

How stable/safe it is?

[Kim Christensen]

Or, even simpler, something like this.

The problem with a Thyristor (SCR) or Triac, is they'll latch on if you use DC... Didn't you say you need to switch BOTH AC and DC?

[nardev]

Yea.. right.. latching is the issue.. I would have to use two pins to unlatch it?

This Photorelay looks so interesting. It's bit expensive but should fit nicely. Just have to find those that are always in stock.

Or, even simpler, something like this.

The problem with a Thyristor (SCR) or Triac, is they'll latch on if you use DC... Didn't you say you need to switch BOTH AC and DC?

[coromonadalix]

SSR   solid state relay  no contacts    5v logic ??

[nardev]

SSR   solid state relay  no contacts    5v logic ??

It's usually quite big for this application.

[Kim Christensen]

SSR   solid state relay  no contacts    5v logic ??

It's usually quite big for this application.

The TLP241A that I posted could also be described as a "solid state relay". That's how I found it on Digikey. You may be able to find something similar from a local supplier if you searched for solid state relay.

If you just want to switch DC only, then single MOSFET could work if the MCU and load share the same power source. It's the AC capability that adds the complication and cost.

[nardev]

SSR   solid state relay  no contacts    5v logic ??

It's usually quite big for this application.

The TLP241A that I posted could also be described as a "solid state relay". That's how I found it on Digikey. You may be able to find something similar from a local supplier if you searched for solid state relay.

If you just want to switch DC only, then single MOSFET could work if the MCU and load share the same power source. It's the AC capability that adds the complication and cost.

I'm thinking.. but i don't know how "stupid" it is, to have separate versions of the device. DC and AC one....

[nardev]

p.s. just realized, TLP241A is not that expensive. Similar to cheap telecom relays.

thnx, good idea...

[tinfever]

Silly idea: Could you put a FET and triac in series? Assuming you can deal with the triac power dissipation?

[BrianHG]

SSR   solid state relay  no contacts    5v logic ??

It's usually quite big for this application.

Big?  How so?  Are you looking for an SOT-23 device?

Everything I listed below are around a 4 to 6 pin dip package, all within your specs...

DC/AC 4 amp Solid state relays aren't too big, only a 4 pin DIP, example:
https://www.digikey.com/en/products/detail/toshiba-semiconductor-and-storage/TLP3553A-F/9472359
5 amp, 6 pin smt/dip device:
https://www.digikey.com/en/products/detail/toshiba-semiconductor-and-storage/TLP3543A-TP1-F/8539918

30v doesn't leave you with any headroom, so you may better choose a 3amp 60v device in a 6pin dip package:
https://www.digikey.com/en/products/detail/toshiba-semiconductor-and-storage/TLP3545-F/3056611

The price is now increasing, bu here is a 40v, 4.5amp device in dip 6 package:
https://www.digikey.com/en/products/detail/bright-toward-industrial-co-ltd/AA28/13556940

And in a funky SMD package, here is 6amp 60v:
https://www.digikey.com/en/products/detail/ixys-integrated-circuits-division/CPC1907B/3908816

I am not sure how small you want to go as you said SSRs are too big, but you wont get too much smaller with multiple discrete back to back mosfets and an opto-photo-voltaic to directly drive the gates, though with this, you can easily achieve 100-500v, 50 to 500amps.  Such solutions will be larger in circuits and complexity than all the SSR ICs I listed above.

[nardev]

Thank you so much.

This is plenty to start.

My quick search into ssr (i didn't have much experience with those) was showing some tall and wide relays... I was trying to avoid that.

10x5x8mm for example is more than good size.

I already included 30-40% of overhead with 28V. So it's safe...