INA213: abnormal current reading

Lei,

there are a few things to check - what do you define as an abnormal low current value?  The INA213 has an offset voltage of up to 100uV, the swing-to-GND could be as high as 50mV, and Current Sense Amplifiers characteristically have worse error as they are operated with small sense voltages.  In the INA213 product folder, you can use the error calculation tool on the sidebar to approximate the potential error of your circuit.  You can see that as you approach 0V sense voltage, the error increases dramatically.

Please let us know more about your circuit (provide a piece of a schematic if possible) and what kind of voltages you expect to see and what you are actually measuring.

Jason, the measured current always good with INA213, but it find that at temperature test ( from -5C to 40C), sometimes it reads abnormal low current value (~50% lower) compared to normal reading current from ADC, so far it suspects ADC or 1 ohm sensing resistor have intermittently quality issue , we want to measure the output from INA213, because ADC read INA213 output, the question is that if the current under measured goes lower by some reason, the INA213's output should also changing? how it should changing? thank you.

As with all semiconductors, the device is affected by temperature, and we spec the drift in the electrical characteristics table and in the typical curves of the data sheet. I'm afraid I can't help much until you give me a better explanation of your setup - All I know is that you have a 5.5V V+, REF=GND, and you have a 1 ohm sense resistor. Do you have a filter on the inputs or output? What currents are you trying to measure? How accurately do you need to measure them? What temperatures are you operating over? What is a good input/output that you see, and what is a bad output for the same input? Please provide us whatever information you can so we can determine what part of the circuit is creating your abnormal readings.