5-6 Source-Measure Concepts
Source-delay-measure cycle
In addition to static source and/or measure operation, SourceMeter operation can consist of
a series of source-delay-measure (SDM) cycles (Figure 5-1). During each SDM cycle, the fol-
lowing occurs:
1. Set the source output level.
2. Wait for the delay.
3. Make the measurement.
Figure 5-2 shows how the SDM cycle fits into the trigger model. See Section 10 for com-
plete details on the trigger model. When the source is turned on (triggered), an approximate
100µsec trigger latency occurs before the programmed source level is output. As long as the
source output stays on, trigger latency will not be included in subsequent SDM cycles. Trigger
latency only occurs when the output makes the transition from off to on. See the specifications
in Appendix A for definitions of trigger latency as well as other trigger specifications.
The delay phase of the SDM cycle allows the source to settle before the measurement is per-
formed. The delay period depends on how the source delay is configured. The source delay can
be manually set from 0000.00000 seconds to 9999.9990 seconds. If using auto delay, the delay
depends on which source range is presently selected, as summarized in Table 3-4; see Section 3
for details.
Measure
End of A/D
Conversion
Source
Value
Trigger
Latency
(100µs)
Trigger
Delay
Start of A/D Conversion
Figure 5-1
Source-delay-measure
(SDM) cycle
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