INA381: Bias current vs. Common mode voltage

Hello Rui,

This is caused by the input stage design of the INA381, and most of our current sense amplifiers. When common-mode voltage is less than or equal to the supply voltage, the device is mainly biased through the supply voltage. However, when common-mode voltage is greater than the supply voltage, the device is biased through the input pins / common-mode voltage. When this happens the typical input bias current changes.

Best regards,

Ian Williams
Applications Manager
Current Sensing