This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

INA181-Q1: Input differential overload in section 8.4.4

Part Number: INA181-Q1

Hello team,

Section 8.4.4 of the data sheet(SLYS018C) has the following description:

Could you give me a detailed explanation of what the last sentence of this explanation means?

(What is "polarity and phase inversion"?)


=== The description in section 8.4.4 on datasheet ===

“When the INAx181-Q1 output is driven to either the supply rail or ground, increasing the differential input voltage

does not damage the device as long as the absolute maximum ratings are not violated. Following these

guidelines, the INAx181-Q1 output maintains polarity, and does not suffer from phase reversal.



H. Someno

  • Hello Hidekazu,

    The description from the datasheet is simply saying that as the differential input voltage (Vin) increases in one direction, the output (Vout) will move in the same direction and once the output rails it will remain at this rail so long as Vin keeps the same polarity.

    So lets consider the INA181A1 (gain = 20V/V) with a 5V supply and REF = GND. As Vin increases, so does Vout, thus they have same polarity. Vout will eventually rail around 5V once Vin = 5V/20 = 250mV. As Vin exceeds 250mV, Vout will remain at the 5V rail. Vout will continue to remain at the 5V rail as Vin sweeps from 0V all the way 28V, which is the Absolute Maximum rating of Vin for this device.

    Some devices may experience a condition called phase reversal. Phase reversal is where Vout collapses to the other rail while Vin is moving in one direction. So an example is as Vin reaches 1V, Vout collapses from 5V to 0V, thus the polarity is reversed. 

    Hope this makes sense.