Hi there,

I am currently having an issue in which I have attached a 10ohm resistor across the outputs of the K2520 test head and when I run a Sweep scan with the following conditions:
  • 0-250mA
  • Compliance set to 3V 
I see the voltage rise in a linear fashion from 0 to 2V for 0-200mA but once it hits 200mA/2V he display starts blinking to indicate it has hit compliance even though the compliance is set to 3V. So for the 200-250mA section the voltage stays consistent at 2V. 

If I then increase the compliance voltage to 4V and re-run the sweep it can reach the 250mA no problem and the voltage continues its linear rise to 2.5V. To follow this up if I then ran a sweep to 350mA with the compliance set at 4V it would have the same issue around 300mA/3V.

The Keithley 2520 is four wire measurement so when I talk about the voltage being measured it is being done by the instrument itself and displayed on the front panel so it is very clear when it indicates it has hit compliance it is actually not at the compliance level. 

A couple of other points to mention to mention:
  • I have checked the voltage signal and it is a clean signal, minimal noise 
  • The range is set to 5V. Increasing the range to 10V made no difference.
Any help would be appreciated,

Many Thanks,

Karl Fisher