Keithley 2520, Руководство пользователя, Страница: 92 / 329

5-10 Source-Measure Concepts Model 2520 User’s Manual
Current source operating boundaries
Limit lines
Figure 5-10 shows the operating boundaries, or limit lines for the laser diode current
source. In the DC mode, the current source can output a maximum of 1A @ 9.9V. In the
pulse mode, the current source can output 5A @ 9.5V. The voltage compliance (limit) can
be set over a range of 3V to 10.5V. The compliance voltage is sensed at the pulser circuit
board, so any I/R drops in the cables or connections is not sensed, and no corrections are
made for these resistances.
Figure 5-10
Current source limit lines
Loading effects
Where within the boundaries each Model 2520 current source operates depends on the
resistance of the load (DUT) that is connected to the output.
Figure 5-11 shows operation
examples for resistive loads that are 50
Ω
and 125
Ω
, respectively. For these examples, the
Model 2520 current source is programmed to source 100mA with a voltage limit of 10.5V.
In Figure 5-11 A, the Model 2520 is sourcing 100mA into the 50
Ω
load and subsequently
develops 5V across the load resistance. As shown, the load line for 50
Ω
intersects the
100mA current source line at 5V.
Figure 5-11 B shows what happens if the resistance of the load is increased to 125
Ω
. The
DUT load line for 125
Ω
intersects the 10.5V compliance limit line placing the Model
2520 in compliance. In compliance, the Model 2520 will not be able to source its pro-
grammed current (100mA). For the 125
Ω
DUT, the unit will output only 80mA (at the
programmed 10.5V limit).
+10.5V
Max
+5A Pulse
Max
+9.5V
+1A DC
Max
+9.9V
Voltage Compliance
Limit Line
Output Current
Current Source
Limit Line
Output
Voltage