Keithley 2520, Service Manual, Page: 120 / 137

A-8 Specifications Model 2520 Pulsed Laser Diode Test System Service Manual
Accuracy calculations
The information below discusses how to calculate accuracy for both measurement and
source specifications.
Measurement accuracy
Measurement accuracy specifications are stated as follows:
Accuracy = ±(% of r offset)
As an example of how to calculate the actual limits, assume an input current of 10mA on
the 20mA range. You can compute the limits from one-year current measurement accu-
racy specifications as follows:
Accuracy = ±(% of r offset)
±[(0.3%
×
10mA) + 65
μ
A]
±(30
μ
A + 65
μ
A)
±95
μ
A
Thus, the reading limits are: 10mA± 95
μ
A, or from 9.905mA to 10.095mA.
Source accuracy
Source accuracy specifications are stated as follows:
Accuracy = ±(% of s offset)
For example, assume a DC source current of 200mA on the 500mA range. Limits are cal-
culated from one-year current source accuracy specifications as follows:
Accuracy = ±(% of s offset)
±[(0.2%
×
200mA) + 0.45mA]
±(0.4mA+ 0.45mA)
±0.85mA
Thus, the actual source current range is: 200mA± 0.85mA, or from 199.15mA to
200.85mA.