Selectable Voltage Output or Current Output reading

[kitepassion]

Hi all,

I have a sensor with a configurable pin. It can be configured to have a voltage output or a current output. They are not the same in the sense that the current is not the translation of the voltage. So I want to clearly be able to measure both of them but without affecting their value. I do not want to affect the current measurement when measuring the voltage and vice-versa.
I need to use a level translator for the voltage reading.
Is the solution provided in the image good? Can you suggest me another solution?

Thank you!

 

[FvM]

Is the solution provided in the image good?

I don't reconize a solution, neither a clear problem specification.

At first sight, a transimpedance amplifier will short an input voltage, so how is the "level translator" supposed to work?

Generally, a current source (sensor with current output, e.g. 0 - 20 mA) generates a voltage when connected to a load and a voltage source (sensor with voltage output, e.g. 0 - 10 V) has an output resistance and generates a current when loaded.

So how does your measurement circuit know if the sensor is operating in voltage or current mode?

 

[kitepassion]

Sorry for the poor specification.

The switch that you see in the sensor is driven by a microcontroller which decides to read a value of voltage from one sensor or a current from another sensor embedded.
So I need at least a switch between the two paths (transimpedence and voltage translator) to de-couple them. Right?

Cheers

 

[FvM]

So I need at least a switch between the two paths (transimpedence and voltage translator) to de-couple them. Right?

Yes. You didn't say if the current measurement is expected to have "zero" voltage drop and must use a transimpedance circuit. If so, there must be a series switch to disconnect the I/V converter. The voltage measurement path can be always connected if it uses a high impedance buffer.

We might ask why you have the front I/V mux and don't use dedicated I and V channels?

 

[kitepassion]

We might ask why you have the front I/V mux and don't use dedicated I and V channels?

The sensor is like this.. I have one channel for I and V with a digital circuit from which I can decide the output I want. Yes the current has zero drop the transimpedence amplifier is needed.

Could I use a BST82 as a switch to deconnect the transimpedence amplifier?

Cheers

 

[FvM]

Could I use a BST82 as a switch to deconnect the transimpedence amplifier?

Yes, if Ron and leakage current specifications are O.K. for your purposes.