Digital potentiometer vs switch

[Markl]

Hi,

We are talking of a DC circuit.

I am a beginner in EE. I read so many things about pull-up resistors, switches, Mosfets that I am currently wondering this:
could we replace them with a digital potentiometer in a circuit?

My logic is that a potentiometer will act on the voltage. Thus, reducing it to near 0 will prevent the current from flowing => same as a switch. By increasing properly the value of the potentiometer to a specified value according to the input pins in case of an IC, we should not have the floating pin problem (we could still use a capacitor right before the pin entry to smooth it out).

As for mosfet, well, I think that being able to digitally activate a part of a circuit is as good as doing it via a mosfet. Or if the power is too high, we could use them in serie: the potentiometer activating the mosfet or not, causing a switch thanks to the input voltage.

Again, I am a beginner trying to put all this knowledge in shape. Please don't hit too hard on me.

I am not saying those parts are useless but a digital potentiometer seems to fill all the boxes of those components to simplify the circuits.Heck it may also enable some power savings too by discarding parts of the circuit. But they -may- be more expensive.

So, why don't I see more digital potentiometers in the schematics I read? Old habit or..?

Thanks folks

 

[BobK]

Switch: low cost, high power handling, operated by a finger.

Digital potentiometer: High cost, low power, operated by a microcontroller.

Pull up resistor: Very low cost. Needs nothing to operate it.

What you propose is about like building a maglev train to carry you next door.

Bob

 

[davenn]

I am not saying those parts are useless but a digital potentiometer seems to fill all the boxes of those components to simplify the circuits

using a digital pot is a far more complicated process

Bob covered the main points/reasons