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5-12 Source-Measure Concepts Model 2520 User’s Manual
Notice that as resistance increases, the slope of the DUT load line increases. As resistance
approaches infinity (open output), the Model 2520 will source virtually 0mA at 10.5V.
Conversely, as resistance decreases, the slope of the DUT load line decreases. At zero
resistance (shorted output), the Model 2520 will source virtually 100mA at 0V.
Regardless of the load, voltage will never exceed the programmed compliance of 10.5V.
In the constant-current mode, the output impedance is extremely high. When the compli-
ance voltage is exceeded, however, the source operates more like a voltage source with a
finite output impedance. The open-circuit (compliance) voltage is programmable from 3V
to 10.5V, and the nominal output impedance is 0.1
Ω
. As a result, the clamping voltage at
the DUT will be lower than the compliance value by the following amount:
V
clamp
at DUT = I
LD
×
(0.1
Ω
+R
cable
+R
fixture
)
Data flow
Data flow for front panel operation is summarized by the block diagrams provided in
Figure 5-12 .
NOTE
See Appendix C for remote operation data flow information, as well as a diag-
nostic tool that allows you to access raw samples.
Basic reading display
With sweeps and math disabled ( Figure 5-12 A), the Model 2520 displays the configured
laser diode voltage and detector current readings.
Math function display
With a math function enabled ( Figure 5-12 B), the Model 2520 displays the configured
math functions. Laser diode math functions include V/I (resistance), I/V (conductance),
power, and MX + B, while only MX + B is available for the two photodiode detector chan-
nels.
Sweep data storage
Figure 5-12 C shows data flow when a sweep is enabled. All data is stored in the buffer
while the sweep is in process. When the recall mode is activated by pressing the RECALL
key, data comes from the buffer. Data includes laser diode source current and voltage mea-
surement, detector current measurements, and buffer location number.
If the math function is enabled, math readings will be processed and displayed for each
buffer location instead of basic voltage and current readings.