TINA/Spice/INA169: Strange spikes from the output of INA169 at low current

The INA169 requires a common mode voltage of 2.7V to 60V to work. Because you are using a fixed resistor as a load, as the current decreases, so does the common mode voltage. In your case, a 1ohm load with 2.7A through it is 2.7V common mode. anytime the current is less that 2.7A, the device may not work properly. The model may not accurately model what happens in that undefined region of operation, so in the real world, large spikes may not exist, but I can't say what will exist. I think modifying the sim to have a fixed common mode and variable current will help your sim considerably. If your actual circuit is a fixed resistive 1ohm load, then make sure the current stays above 2.7A. Also note that the common mode rejection of the device is 120dB, min 100dB, at 50mV input. Having a voltage swing on the inputs of ~50V will have an effect on the output just by itself, even if the current was constant. Just something to keep in mind as you do your design and sims.

Hello Jason,
thank you for your good explanation, I will keep in mind.
Thank you

Martin