What is a compliance limit setting?

Today we will talk about what "compliance limit" is and what it means.

Compliance is an instrument setting you can specify when using sourcemeters. If you are working in voltage source mode, you set the compliance limit as a current value. Vice versa, if you are working in current source mode, you set a voltage compliance limit instead.

For obvious reasons, compliance limit has to be consistent with the measurement range you set for the same parameter, current or voltage. That means the instrument will “protect” you by using the lower of the two values, considering that if you set a limit of 100mA when your measurement range chosen is 10mA only, you might have done something wrong. This called a “range compliance” condition, and it's more a condition you run into rather than an intentional setting.

When your instrument reaches the compliance state (a real one, you intentionally programmed), it still works as a constant current source (or voltage source) within the limit you set. The reason why you would set this limit is simple: you do not want to damage your Device Under Test (D.U.T.), or simply you do not want to risk to heat it up too much.

But if you are in compliance mode, you are effectively somehow clamping your source, that means some circuitry is applied to do that. So, if you enter this condition, on purpose or not, do not simply take the measurements and copy then in your report. Check values, signals, think about on what is going on, why you reached the compliance, if you expected it and eventually take the unit out of the condition. No instrument or feature can replace your common sense, knowledge and intelligence to interpret it.

Do you use compliance limit setting in your setup? For what reason? Please share with us