User Manual

A-2 Specifications 2400 Series SourceMeter
®
User’s Manual
Accuracy calculations
The information below discusses how to calculate accuracy for both sense and
source functions.
Measure accuracy
Measurement accuracy is calculated as follows:
Accuracy = ±(% of reading + offset)
As an example of how to calculate the actual reading limits, assume that you are
measuring 10V on the 20V range. You can compute the reading limit range from
one-year measure voltage accuracy specifications as follows:
Accuracy = ±(% of reading + offset)
=±[ (0.015% × 10V) + 1.5mV]
= ±(1.5mV + 1.5mV)
=±3mV
Thus, the actual reading range is 10V ± 3mV or from 9.997 to 10.003V.
DC current measurement calculations are performed in exactly the same manner
using the pertinent specifications, ranges, and input signal values.
Source accuracy
Source accuracy is calculated similarly, except source specifications are used. As
an example of how to calculate the actual source output limits, assume that you
are sourcing 0.7mA on the 1mA source range. You can compute the reading limit
range from source current one-year accuracy specifications as follows:
Accuracy = ±(0.034% of output + 200nA offset)
= ±[(0.034% x 0.7mA) + 200nA)]
= ±(238nA + 200nA)
= ±438nA
In this case, the actual current output range is 0.7mA ±438nA or from 0.69956mA
to 0.70044mA.