Voltage Scaling

Other Hardware General Electronics
1

Hi,

Hope someone can share some insight into how to accomplish this problem. Normal voltage scaling assume some kind of commonality for example 0-3.3V must be scaled to 0-5V or 0-12V where 0V being common.

I have a problem where I need to scale (expand) the voltage range (0.547V - 2.757V) to (0V - 5V).

Any suggestions would be welcome.

Thanks

2

Would the map() function do what you want ?

3

Hi,

Unfortunately this is not a code function, but more a physical electronics problem. I was thinking of using op-amps but I am not sure how to go about constructing it.

Thanks

4

It would help to know why you want to do this.

To add or subtract a constant voltage pass a constant current through a resistor, that will give you a constant voltage that you can add to what you have. In your case you need 0.547V to get down to 0V, giving you a range of 0V to 2.21V. Once you have that you can use a simple op-amp to get the range you want. You will need a negative supply rail. You will also need a very clean power supply; linear regulators and don't skimp on the decoupling capacitors.

5

First, a differential amp with your raw voltage on the + input and 0.547V on the - input, output to a non inverting amp with a total gain of 2.2624.
2.757 - 0.457 = 2.21 * 2.26244343891 = 5.

6

Use the circuit and equation from here perhaps? A rail-to-rail opamp is required.

7

An XY-problem maybe? What generates the voltage and why do you need to scale it up to 0-5V? What precision do you expect? Do you need linearity?

8

Full schematic of the system this is for would help... there may be a higher voltage source but who can guess, there may even be +/- rails?

9

Hi Everyone,

Thanks for the inputs. My Achilles heel in life is I try to think too difficult.

There is no circuit that I have just an idea that I woke up with one morning, of how to solve a problem should it present itself one day.

I know the circuit is probably not 100% correct but the concept works. I have attached the circuit showing the low and high side results.

Thanks again everyone...

High Side.png
High Side.png883×505 8.49 KB

Low Side.png
Low Side.png885×504 8.52 KB

10

The single stage opamp differential amp circuit I linked to in #5 can do it all - set the reference voltage
for the offset, set the resistor values to set the gain.

The reference voltage can be set by splitting that Rf into two resistors one to 0V one to 5V. Their parallel
equivalent resistance must be Rf, their ratio sets the voltage.