Current sensing circuit with LT1495 : need help

[radioactive1014]

Hi,
I am designing a circuit for my University project which involved measuring the current drawn by the load. I am using LT1495 rail to rail opamp. I have attached the circuit here. It's a simple differential amplifier with 4 resistors. Circuit works fine when the current is higher than .34 A. Whenever the current goes below .34 it can't sense anymore ( the output remains .34 ).



I would appreciate if anyone can help me solving the problem. Another thing is as I am on deadline I already ordered the PCB (it was very stupid of me ). so I can't change the circuit but all I can do is to change the value of the resistors. Is it possible to make it work?

Thanks for your help in advance.

 

[chuckey]

It all depends on how your current sensing resistor is referenced to the opampd earth line.
Frank

 

[radioactive1014]

It all depends on how your current sensing resistor is referenced to the opampd earth line.
Frank

Hi,
I have used the op amp as single supply input, means I have given 9 volts to V+ and grounded the V- .

 

[chuckey]

The current sensing resistor is in series with the main current path for the power supply, so how is the opamps supply tied to the main power supply?. Have you measured the voltage on each side of this resistor using the opamps supply as a reference?
Frank