I have several battery-powered projects in the works where I can potentially draw more current than I would be comfortable running directly through a switch. I found the following boards on Pololu that seem to accomplish this, as well as adding reverse voltage protection:

https://www.pololu.com/product/2811

I looked over the schematic and removed some of the options that I don't want, such as multiple options for switches. I quickly redrew the schematic and I think it makes sense (without getting to deeply into the weeds with exact part values). The load would be LEDs, servos, microcontrollers, etc.

It's been a while since I've tried to use MOSFETs, so I'd appreciate any constructive criticism, including where it would be prudent to have decoupling caps. I'm also not sure if that's a good spot for a fuse (S2) or not.

 

I have several battery-powered projects in the works where I can potentially draw more current than I would be comfortable running directly through a switch. I found the following boards on Pololu that seem to accomplish this, as well as adding reverse voltage protection:

How high is the current that you can' run through a switch?
That board has a maximum current rating of 4A, which many switches can readily handle.

 

The switches that I can find with a viable (I know that's subjective) DC amperage rating listed have a form factor that is larger than I prefer/require. The goal is to use the smallest switch (like a mini slide switch) possible, while allowing the load on the back end to change as needed without being concerned about the switch (which may also change from project to project). Additionally, I only reference that particular board as a data point to figure out a schematic; I've yet to pick the exact component values.

Anecdotally, I've typically just used switches (small toggles) directly, and it never gives me the warm and fuzzies as far as robustness and consistency is involved. That's caused me to look into other solutions such as this.

 

That circuit puts the two MOSFETs in series. Don't you want them in parallel?

And, is there a reason you want to switch the high side? It would be simpler to switch the low side with N-channel MOSFETs.

Oops, just saw the reverse-voltage protection.

 

After looking this over again, I can't see why it wouldn't work, unless I'm completely missing something.

 

It will work. Linear Tech has several hot swap and electronic circuit breaker control chips that use external back to back MOSFETs. Roam around in their datasheets and app notes for more background.

If I were designing it from scratch: Since the DC input is less than 20 V, I would delete D1 and R2, connect R3 between the sources and gates, and connect the switch directly to the gates (and GND).

ak

 

It will work. Linear Tech has several hot swap and electronic circuit breaker control chips that use external back to back MOSFETs. Roam around in their datasheets and app notes for more background.

If I were designing it from scratch: Since the DC input is less than 20 V, I would delete D1 and R2, connect R3 between the sources and gates, and connect the switch directly to the gates (and GND).

ak

AK, is this what you are suggesting? The values are still more or less placeholders until I decide on specific components.

 

Yup.

 

Awesome. I suppose the next step is picking actual components and doing some math.

Would decoupling be required (a good idea) in this circuit?