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Section Topics
2400S-903-01 Rev. E / September 2011
Section 1: Introduction
Series 2400 SourceMeter® Quick Start Guide
Speed
Measurement speed is set by setting the integration time of the A/D converter (period of time the
input signal is measured). Integration time affects the usable digits, reading noise, and the ultimate
reading rate of the instrument. It is specified in parameters based on the number of power line
cycles (NPLC), where 1 PLC for 60Hz is 16.67msec (1/60), and 1 PLC for 50Hz and 400Hz is
20msec (1/50).
In general, the fastest speed setting (FAST; 0.01 PLC) results in increased noise and fewer usable
display digits. The slowest speed (HI ACCURACY; 10 PLC) provides the best common-mode and
normal-mode noise rejection. In between settings are a compromise between speed and noise.
Press SPEED and select one of the following speed setting options:
NOTE After setting speed, display resolution can be changed using the
DIGITS key.
Digits
The SourceMeter can display readings at 3
H
-digit, 4
H
-digit, 5
H
-digit or 6
H
-digit resolution. In situations
where the last digits of the reading are noisy, you can turn those digits off by decreasing display
resolution.
To set display resolution, press the DIGITS key until the desired number of digits are displayed.
Another way to set display resolution is with the following menu sequence:
Press CONFIG > press DIGITS > select 3.5, 4.5, 5.5, or 6.5.
NOTE Changing DIGITS does not affect measurement SPEED, but
changing measurement speed does affect DIGITS.
Filter
Filtering is used to stabilize noisy readings. In general, the more filtering that is applied, the more
stable (and accurate) the reading. However, more filtering also means slower speed.
The filtering process consists of filling a stack with the specified number of reading conversions
(filter count), and then averaging them to yield a filtered reading. The SourceMeter has two filter
types; moving and repeating.
Repeating filter
The stack is filled with the specified number of reading conversions. The reading conversions are
averaged to yield a filtered reading. The stack is then cleared, and the process starts over. Use
this filter for sweeping so readings for other source levels are not averaged with the present
source level.
FAST
Sets speed to 0.01 PLC and display resolution to 3
H
-digits.
MED
Sets speed to 0.10 PLC and display resolution to 4
H
-digits.
NORMAL
Sets speed to 1.00 PLC and display resolution to 5
H
-digits.
HI ACCURACY Sets speed to 1.00 PLC and display resolution to 5
H
-digits.
OTHER
Use to set speed to any PLC value from 0.01 to 10. Display reso-
lution is not changed after speed is set with this option.
