2600AS-901-01 Rev. B / September 2008
Return to
4-3
Series 2600A System SourceMeter® Instruments Reference Manual
Section 4: Source-Measure Concepts
source will switch from a V-source to an I-source (or from an I-source to a V-source) when in
compliance.
As an example, assume the following:
SourceMeter instrument: V
SRC
= 10V; I
CMPL
= 10mA
Device under test (DUT) resistance: 10
Ω
With a source voltage of 10V and a DUT resistance of 10
Ω
, the current through the DUT should
be:
10V / 10
Ω
= 1A
. However, because the compliance is set to 10mA, the current will not exceed
that value, and the voltage across the resistance is limited to 100mV. In effect, the 10V voltage
source is transformed into a 10mA current source with a 100mV compliance value.
Overheating protection
Proper ventilation is required to keep the SourceMeter instrument from overheating. Even with
proper ventilation, the Series 2600A can overheat if the ambient temperature is too high or the
SourceMeter instrument is operated in sink mode for long periods of time. The SourceMeter
instrument has an over-temperature protection circuit that will turn the output off in the event that
the instrument overheats. If the output trips due to overheating, a message indicating this condition
will be displayed. You will not be able to turn the output back on until the instrument cools down.
Power equations to avoid overheating
To avoid overheating, each channel on the Series 2600A should not be operated in a manner that
forces the instrument to exceed the maximum duty cycle (DC
MAX
) computed using the
SourceMeter instrument power equation
below. Factors such as the ambient temperature,
quadrant of operation, and high power pulse levels (if applicable) affect the maximum duty cycle.
Exceeding the calculated maximum duty cycle may cause the temperature protection mechanism
to engage. When this happens, an error message will be displayed, and the SourceMeter
instrument output will be disabled until the internal temperature of the SourceMeter instrument is
reduced to an acceptable level.
You do
not
have to be concerned about overheating if
all
of the following are true:
•
The SourceMeter instrument used as a power source and not a power sink.
•
The ambient temperature is
≤
30°C.
•
High power pulse operation is not being used.
However, if any one of these is false, the SourceMeter instrument may overheat if operated in a
manner that exceeds the calculated maximum duty cycle, DC
MAX
.
The maximum duty cycle equation is derived from the power equation below by solving for DC
MAX
.
The general power equation describes how much power a SourceMeter instrument channel can
source and/or sink before the total power cannot be fully dissipated by the Series 2600A cooling
system. This equation takes into account all of the factors that can influence the power being
dissipated by the SourceMeter instrument.
