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INA381: Some questions about clipping behavior effects

Part Number: INA381

Hi,

A customer of mine has some questions about it's behavior. They are trying to change the status of the output alert at a current of 0.5mA and reference of 0.5V. 

Normally there should be a current of 5mA (10mA max), with 5V (10V max) at the output of the opamp VOUT, but the opamp is only fed with 3.0V of supply. So the output is clipping. 

What are the disadvantages? Is there any recovery behavior? Are there any unexpected effects?

Or is it important to never led the output clip, e.g. at INA381A1 (gain 20) and reference 100mV?

Thank you in advance for looking at this!

  • Hello JuMar,

    Thanks for using our forum. I think you may need to elaborate some on your question (possibly include a diagram too), I am not following your train of thought on this.

    I interpret the your second line of this post as: your customer's supply is 3V and they want to force the output to between 5V and 10V.
    That is not good for the longevity of the device. While the output impedance is not currently supplied in our datasheet, I can say that it should be rather low and driving the output will result in a lot of current being sunk and possible part failure.

    I interpret your fourth line in this post as: the customer has a wide current range and they only designed the current shunt monitor for the lower part, which means that if the current crosses into the upper operating range, the INA381 output rails to 3V. If this is the case, I believe their motivation would be for detecting if the load was actually ramping up, with the intent of alerting the system to power up other parts in the system. You might ask why not just monitor the whole current range. Our devices, including the INA381, have a finite measurement range. The shunt, gain, and supply dictate the highest current, while the device input bias current and input offset voltage dictate the lower bound. By looking at only the lower range of measurement, they can achieve greater resolution over that smaller range and more precisely trigger at a certain threshold. By focusing on the smaller range, they can also make the device cross the hysteresis point sooner.
  • Hello JuMar,

    We have not heard from you in a while. As such, we presume the above post helped you resolve your issues and we therefore are going to close this thread. However, if you need further support, please reply below to reopen the thread.