Part Number:INA240
I have designed a board with many INA240A2 for current sensing. Some, but not all of the parts will power up with the output ground. The output should be at 1.024V due to a 2.048V offset applied to REF1, and REF2 grounded.The power supply is regulated to 5.1V. The inputs are across a 0.02 ohm sense resistor and held strongly at ground at startup. If I increase the common mode voltage to 1V, then the output goes to the expected 1.024V. Taking Vcm back to zero, the INA240 output returns to 0. According to my reading of the datasheet, the part should be functioning properly with Vcm from -4V to +80V. The individual chips are all marked I240A2 and 86KG4. What is going on ?