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Model 2790 SourceMeter
The front panel RATE settings for all but the AC functions are explained as follow:
•
•
•
For the AC functions (ACV, ACV dB, and ACI), the RATE key sets integration time and
bandwidth. As listed in
NPLC settings are ignored (see
Table 4-4
Rate and bandwidth settings
DCV, DCI
ACV, ACI
Ω2, Ω4
FREQ, PERIOD
Continuity
Notes: NPLC = number of power line cycles.
From the front panel, setting the rate for one function affects all the other functions. For
example, if you set DCV for medium speed, the other functions will also set to medium
speed. For remote programming, each function can have its own unique rate setting (0.01
to 50 or 60 PLC).
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Setting measurement speed — The RATE key is used to set measurement speed from the
front panel. Simply press RATE until the desired speed annunciator (FAST, MED, or
SLOW) turns on.
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®
Switch System Reference Manual
FAST sets integration time to 0.1 PLC. Use FAST if speed is of primary impor-
tance (at the expense of increased reading noise and fewer usable digits).
MEDium sets integration time to 1 PLC. Use MEDium when a compromise
between noise performance and speed is acceptable.
SLOW sets integration time to 5 PLC. SLOW provides better noise performance at
the expense of speed.
Table
Function
NPLC=0.1
NPLC=1, BW=300
NPLC=0.1
APER=0.01s
NPLC=0.01
BW = lower limit of bandwidth (in Hz).
APER = aperture in seconds.
N/A = not available.
X = setting ignored.
Rate cannot be set for continuity. It is fixed at 0.01 PLC.
The Model 2790 uses internal references to calculate an accurate and stable
reading. When the NPLC setting is changed, each reference must be updated to
the new NPLC setting before a reading is generated. Therefore, frequent NPLC
setting changes can result in slower measurement speed.
4-4, FAST sets NPLC to 1, while the MEDium and SLOW
"Bandwidth," page
4-10, for details).
Rate and bandwidth
Fast
Medium
NPLC=1
NPLC=X, BW=30
NPLC=1
APER=0.1s
N/A
Slow
NPLC=5
NPLC=X, BW=3
NPLC=5
APER=1s
N/A
4-9
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