# Current Sense Amplifier Potentials

I'm trying to implement a current sense amplifier in my application, but I have a question about setting it up with regards to current flow.

Basically, in this case, you put a very small shunt resistor between the source and the load, and the current sense amplifier measures the voltage across it, and outputs a voltage in accordance with the current flow. This is shown below using the INA293.

However, this assumes a positive voltage at the load supply with respect to GND, being 0 volts, and most likely, $$\R_{Sense}\$$ is small enough such that the voltage drop is negligible. For my application, I'm considering using it with the LM2673 circuit that outputs a negative voltage shown below. In this case, GND would be the more positive node w.r.t. $$\V_{OUT}\$$, so current will flow from GND to $$\V_{OUT}\$$. So, to rework the current sense circuit, the Load Supply would be GND, GND would be $$\V_{OUT}\$$, and the opamp's GND node would be connected to $$\V_{OUT}\$$. If I were to place the sense resistor between the Load and $$\V_{OUT}\$$, would the current sense amplifier work properly, or is there something that would not cause it to work?

EDIT: Proposed Application Circuit:

simulate this circuit – Schematic created using CircuitLab

Rough Schematic idea with Comparator OpAmp:

simulate this circuit

• what is your application? draw a new schematic to clarify how you plan to use your current sensor? – Ocanath May 18 at 21:16

Based on your description, it seems like you mean that you want to implement something like the circuit below. This is essentially the same circuit, using your switch mode inverter as a virtual ground. As long as $$\ V_{s+} - V_{s-} \$$ is less than 22V (the rated supply voltage of your current sense amplifier) there is nothing wrong with this circuit (or really, anything different from the application diagram from the datasheet that you posted).
Note that if you want to connect the output of this current sensor to something else, it will also need to be referenced to $$\ V_{s-}\$$.