2600AS-901-01 Rev. B / September 2008 Return to Section Topics 3-13
Series 2600A System SourceMeter® Instruments Reference Manual Section 3: Basic Operation
Sink operation and interface
When operating as a sink (V and I have opposite polarity), the SourceMeter instrument is
dissipating power rather than sourcing it. An external source (for example, a battery) or an energy
storage device (i.e., capacitor) can force operation into the sink region.
For example, if a 12V battery is connected to the V-Source (In/Out HI to battery high) that is
programmed for +10V, sink operation will occur in the second quadrant (Source +V and
measure - I).
CAUTION When using the I-Source as a sink, ALWAYS set V-Compliance to a level
that is higher than the external voltage level. Failure to do so could result in
excessive current flow into the SourceMeter instrument (<102mA) and
incorrect measurements. See Compliance limit for details.
NOTE The only exception to the compliance limit not being exceeded is the
VLIMIT when operating as an ISOURCE. To avoid excessive (and
potentially destructive) currents from flowing, the VLIMIT will source
or sink up to 102mA for ISOURCE ranges on or below 100mA. For
the ranges 1A and above, the maximum current allowed is the
current source setting.
The sink operating limits are shown in General SourceMeter instrument power equation in
Section 4.
Ohms measurements
Ohms calculations
Resistance readings are calculated from the measured current and measured voltage as follows:
R = V/I
Where: R is the calculated resistance
V is the measured voltage
I is the sourced current
Ohms ranging
The front panel ohms function does not use ranging. The unit formats a calculated V/I reading to
best fit the display. There may be leading zeros if the ohms reading is very small (<1mΩ).
Basic ohms measurement procedure
Perform the following steps to perform ohms measurements. The following procedure assumes
that the SourceMeter instrument is already connected to the DUT as explained in
Section 2.
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