Section 2: General operation
Model 2651A High Power System SourceMeter® Instrument Reference Manual
2-66
2651A-901-01 Rev. A / March 2011
Maximum source values and readings
The full-scale output for each voltage and current source range is 101 percent of the selected range,
but the full-scale measurement is 102 percent of the range. For example, ±5.05 A is the full-scale
source value for the 5 A range, and ±102 mA is the full-scale reading for the 100 mA measurement
range. Input levels that exceed the maximum levels cause the overflow message to be displayed.
Note, however, that the instrument will autorange at 100 percent of the range.
Measure auto delay
The measure delay is a specific delay applied before each measurement is taken. This delay is
disabled by default (measurements are taken immediately). You can either change the default delay
by setting the
(on page 7-195) attribute to a specific value or to an auto delay
setting (set
smu
X
.measure.delay = smu
X
.DELAY_AUTO
). If the measure delay is set to the auto
delay setting, a range-dependent delay is applied each time the instrument performs a current
measurement, or after changing current ranges during an autoranged measurement. The following
table contains the measure auto delays associated with each current range.
Range
Measure auto delay
10 mA (and above)
0
μ
s (no delay)
1 mA
100
μ
s
100
μ
A 150
μ
s
10
μ
A 500
μ
s
1
μ
A
2.5 ms
100 nA
15 ms
You can increase or decrease the auto delay by changing the delay factor (for example, to reduce the
delay across all ranges by half, set
smu
X
.measure.delayfactor = 0.5
). For additional
Ranging limitations
•
Model 2651A:
The maximum output power and source/sink limit for the Model 2651A is 202 W
per channel (maximum). With the 40 V (V-Source) range selected, the highest current
measurement range is 5 A. Refer to
(on page 4-5) for power derating
information. When pulsing with the 50 A I-Source range selected, you can be at a larger voltage
range than 4 V dependent on your duty cycle. See
•
Source V Measure I or Source I Measure V:
You can set source and measure ranges
separately, but if both source and measure functions are the same, the measure range is locked
to the source range.
