User manual

5-6 Pulse Mode Operation (Model 2430 only) 2400 Series SourceMeter
®
User’s Manual
Pulse Width Delay = 1msec - 167µsec - 80µsec = 753µsec
NOTE If the result of the pulse width delay calculation is a negative number,
pulse width delay is set to 0sec. A negative number indicates that the
pulse width setting is too short (not achievable).
Output off-time
Reference and zero measurements
As previously explained in “Pulse width,” “Signal measurement,” the reference
and zero measurements for a pulse reading are performed during the output off-
time of the pulse period (Figure 5-2). The time to perform these two measure-
ments depends on the speed setting (NPLC) of the SourceMeter and the power
line frequency:
Meas Ref & Zero = 2 x NPLC / Line Frequency
Where: Meas Ref & Zero is the time it takes to measure the reference and zero.
NPLC is the present speed setting (0.004 to 0.1 PLC).
Line Frequency is the frequency of the power line (50 or 60 Hz).
Overhead time
As shown in Figure 5-2, there is some overhead time that is inherent to the
source-measure process. The 2.9msec is the minimum overhead time for a
source-measure cycle that can be achieved during the output off-time. The mini-
mum output off-time may vary depending on instrument settings (see Table 5-1 on
page 5-4 for details). If the SourceMeter is configured to perform additional opera-
tions (e.g., math calculations, relative, store, sweep), this time will be higher.
Pulse delay
The pulse delay (PD) is set by the user. It can be set from 0 to 9999.999sec. The
total output off time is the addition of the pulse delay, auto zero measurement
time, and the minimum output off time of the instrument.
Pulse duty cycle
Duty Cycle is the percentage of time during the pulse period that the output is on.
It is calculated as follows:
Duty Cycle = Pulse Width / (Pulse Width + Off-time)
For example, if the pulse width is 1msec and the off-time is 9msec, the duty cycle
is calculated as follows: