Keithley 2657A User Manual

Model 2657A High Power System SourceMeter® Instrument Reference Manual Section 4: Theory of operation
2657A-901-01 Rev. B/December 2012 4-7
Load considerations (V-source)
The boundaries within which the High Power System SourceMeter
®
instrument operates depends on
the load (device-under-test (DUT)) that is connected to the output. The following figure shows
operation examples for resistive loads that are 200 kΩ and 80 kΩ, respectively. For these examples,
the System SourceMeter instrument is programmed to source 1000 V.
In the following figure (labeled "Normal V-source operation"), the System SourceMeter instrument is
programmed to limit current to 10 mA. The System SourceMeter instrument is sourcing 1000 V to the
200 kΩ load and subsequently measures 5 mA. As shown, the load line for 200 kΩ intersects the
1000 V voltage source line at 5 mA. The current compliance limit is not reached (the instrument is not
limited through its compliance settings).
Figure 71: Normal V-source operation
The next figure (labeled "V-source operation in current compliance"), shows what happens if the
resistance of the load is decreased to 80 kΩ. For this example, the System SourceMeter instrument is
programmed to limit current to 10 mA. The DUT load line for 80 kΩ intersects the current compliance
limit line placing the System SourceMeter instrument in compliance. When in compliance, the System
SourceMeter instrument will not be able to source its programmed voltage (1000 V). For the 80 kΩ
DUT, the System SourceMeter instrument will only output 800 V (at the 10 mA limit).
Figure 72: V-source operation in current compliance
V-source
(V
S
)
I-meter
(I
M
)
Operating
point
200
kΩ
DUT Load Line (R)
I
M
= V
S
/ R
= 1000 V / 200 kΩ
= 5 mA
Programmed voltage
source value line
L
(
R
)
Current
compliance
limit line
Programmed source value:
1000 V
Actual source value:
1000 V
5 mA
10 mA
1000 V
500 V
V-source
(V
S
)
I-meter
(I
M
)
Current
compliance
limit line
Operating
point
V
S
= I
M
• R
= (10 mA)(80 kΩ)
= 800 V
80
kΩ DUT Load Line (R)
Programmed voltage
source value line
n
e
L
Programmed source value:
1000 V
Actual source value:
800 V
5 mA
10 mA
1000 V
500 V

Keithley 2657A Specifications

General

Brand	Keithley
Model	2657A
Category	Measuring Instruments
Language	English