Will this range switch circuit work correctly?

[teslinius]

I made a circuit that will switch between the 2 resistor dividers for more precise voltage measurement, at first i used 2 n channel mosfets and 2 gpio pins but now i though up of this circuit to save a gpio pin, will it work correctly?, when gpio is high the top resistor divider will pass and the bottom one when gpio is low.

[teslinius]

Oh and also should the ALERT/RDY pin be pulled high or low, because in the datasheet it doesn't say?

[Benta]

Just a suggestion:
https://www.vishay.com/docs/76471/dg2001e.pdf

Plenty of analog switches around. That might not be the right one, but...

[Doctorandus_P]

Nope. Probably won't work.
Watch those body diodes of the Fets.
A high voltage on R36 will conduct through to U20 even if Q7 is off, and Q12 will also conduct it to the R39 & R38 voltage divider.

You can put two MosFet's in "anti series" by connecting both gates and sources together, but that will still need extra attention to drive it with a proper gate voltage.

So your alternatives are good old fashioned reed relays, analog switch IC's or "photomos" relays.


But also:
Such circuits are both easy to simulate and to build on a breadboard. So build some circuits and measure them to get some more hands-on experience.

[gcewing]

Even if you solve the body diode problem, you will still have to be careful that you have enough gate-to-source voltage to turn the fets fullty on under all conditions.

I second the recommendation to use some kind of analog switch or multiplexer chip, it will take care of all this for you.