Using a MOSFET Relay over a Mechanical Relay

[nearxosp]

I am in the process of design a PCB board for a project.

In a few words a PIC micro controller will control 2 solenoid valves and 1 peristaltic pump.
my design was to use 3 mechanical relays that will then turn on and off the components. but as i am going through my design again i am leaning to replacing the mechanical relays with MOSFET relays (like or something similar).

As this is the first time i am making something like this (making a PCB from scratch) i am concern to which MOSFET relay to choose. and how to connect it.

below i have attach my relay driver schematic as i have it right now with mechanical relays.

 

[KlausST]

Hi,

a frequetly asked question. Thus there are discussions/solutions in the forum already.

some questions about o your circuit.
* an optocouper is for isoation. Do you need isolation at all?
* a relay provides isolation. A gain: do you need isolation? The relay connection seems that you don´t need isolation at all.
* do 5V and 12V reference to the same ground?

***
from what I see .. you don´t need isolation. Thus you dont need a relay. A simple logic level MOSFET (plus a freewheeling diode) will do the job.

****
Part selection:
Just go the the internet site of the distributor of your choice and use the according selection tool. Then input your design parameters. We don´t know them.
You will find many parts fitting to your requirements. You are free to choose...

Klaus

 

[std_match]

If you want short circuit protection, look at automotive low-side switches. One possible manufacturer is Infineon (they also have "normal" MOSFETs).

 

[nearxosp]

i used the optocoupler as the input signal from the microcontroller is 5 volt and the relay need 12V.

i ve look at different examples online and thats how they do it

 

[KlausST]

Hi,

makes no sense to me.
You may use T2 without the use of the optocouper to drive the 12V relay with an 5V logic signal.

Klaus

..and I think you even don´t need the relay.

 

[nearxosp]

OK I understand. Appreciate your help.
So if i replace the Relay with a Mosfet, will just control the mosfet straight through the output of the micro controller