Keithley 2520, User Manual, Page: 253 / 329

A-4 Specifications Model 2520 User’s Manual
Accuracy calculations
The following information discusses how to calculate accuracy for both measurement and
source functions.
Measurement accuracy
Measurement accuracy is calculated as follows:
Accuracy = ±(% of r offset)
As an example of how to calculate the actual reading limits, assume that you are measur-
ing 5V on the 10V laser diode measurement range. You can compute the reading limit
range from one-year measurement specifications as follows:
Accuracy = ±(% of r offset)
= ±
[(
0.3%
×
5V) + 8mV]
= ±(15mV+ 8mV)
= ±23mV
Thus, the actual reading range is 5V ±23mV or from to 4.977V to 5.023V.
Source accuracy
Source accuracy is calculated similarly, except that source specifications are used to calcu-
late source accuracy as follows:
Accuracy = ±(% of s offset)
As an example of how to calculate the actual source output limits, assume that you are
sourcing 100mA DC on the 500mA range. You can compute the output limits from laser
diode current source one-year accuracy specifications as follows:
Accuracy = ±(0.2% of s 0.45mA offset)
= ±[(0.2%
×
100mA) + 0.45mA]
= ±(0.2mA + 0.45mA)
= ±0.65mA
In this case, the actual current source output range is 100mA ±0.65mA or from 99.35mA
to 100.65mA.